Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Grees01 on January 07, 2022, 03:32:57 pm
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Hello everyone. New to the forum. Introduced myself in the into area. Would like to build a hand wired amp. Been reading up on Rob Robinettes website and following Uncle Dougs videos. Considering what amp to build. I'm looking for lovely 3d clean and a little grit when I dig in with the pick. Some harmonic overtone depending on my playing dynamics. I've been considering the bassman circuit with a few mods that Rob lays out. I need a multi output OT so I can use it with my existing cabinet. I want adjustable bias so I can run different power tubes. The modification to the power tube sockets so I can run el34 power tubes if desired. An adjustable feedback loop circuit. Backup diodes on the rectifier tube, and possibly diode rectification thats swichable. Pentode / triode switching on the power tubes for a 1/2 power mode. Possibly voicing a lead channel. I would like some feedback from you guys on what you think about this choice for a guitar amp. Suggestions and recommendations welcome.
G. Rees
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I built a 5F6A using the hoffman board that I also built myself and I have always run EL34s in it and its a great amp. Mine is a little different in that it has a very large choke input which I think gives it a little character, and smoothness. I haven't really turned it up to as loud as it can go but on the attenuator it does growl a bit. I think it's perfect for pedals.
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Hello Grees,
Welcome to the forum! I'm sure you will find (like I did) that the members and moderators of this forum will give you great advice on building and troubleshooting an amp. You've come to the right place.
I am literally in the middle of a JTM45 build, which is the UK sibling of the Fender Bassman. While opinions vary, either one of these amps is considered by many the Holy Grail of classic guitar tone.
Prior to starting my JTM45 build, I was thinking of incorporating many of the same things you listed....switchable rectifiers, switching for different NFB resistors, switchable 6V6/KT66, and also things like switchable cathode resistors on V1, different "eras" for tone stacks, etc. I settled on just building pretty much a bone stock JTM45. Why?...two reasons...1) the amp is classic for a reason. Why implement a build with all of these bells and whistles I might not even want or like, and 2) adding these other features exponentially complicates things, especially for a novice builder trying to get through the troubleshooting phase.
Once you build the amp and get it up and running, you can start implementing these other features. If you are creating your own turret board (like I did for my JTM build) you can think ahead and have spaces on your board layout that will be ready to go when you get to the point of trying them out. For example, I have a spot on my board for a split cathode on V1, but will start off with the shared cathode.
I think your best bet for easily incorporated mods would be the switchable NFB, possible switch for shared/split V1 cathode, and maybe a switchable bypass cap on V2a ("lead voicing" maybe?). You could install temporary switches on the side of the chassis (vs front or rear) to avoid any permanent changes to the panels, and once you decide on the ones you like, you can incorporate those on the front or real panel.
Hope this helps, and best of luck with the process! Once you get started on this, it becomes an addiction.
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I should add that a non-stock feature you mention that would be a "must do" addition would be a bias trim pot, as you pointed out for handling various tube types.
You can find Doug's board with this incorporated here: https://el34world.com/schematics.htm#Hoffman_5F6A_Bassman_ (https://el34world.com/schematics.htm#Hoffman_5F6A_Bassman_)
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Welcome to the forum!
Here a very handy link: ALL-TIME great information (https://el34world.com/Forum/index.php?topic=23286.msg250136#msg250136)
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I built a 5F6A using the hoffman board that I also built myself and I have always run EL34s in it and its a great amp. Mine is a little different in that it has a very large choke input which I think gives it a little character, and smoothness. I haven't really turned it up to as loud as it can go but on the attenuator it does growl a bit. I think it's perfect for pedals.
Thank you for the feedback. Did you build this as a head unit? Or did you build it as a combo?. Any changes to the original circuit? Other than the different choke? Can you post a sound clip? Or video of you playing thru it? How is the clean sound? vs the driven sound? Does it sound good at lower volume levels, or do you have to crank it pretty loud for it to sound good. Overall are you happy with it? In love with it? Or just okay with it?
Glen
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I am literally in the middle of a JTM45 build, which is the UK sibling of the Fender Bassman. While opinions vary, either one of these amps is considered by many the Holy Grail of classic guitar tone.
Prior to starting my JTM45 build, I was thinking of incorporating many of the same things you listed....switchable rectifiers, switching for different NFB resistors, switchable 6V6/KT66, and also things like switchable cathode resistors on V1, different "eras" for tone stacks, etc. I settled on just building pretty much a bone stock JTM45. Why?...two reasons...1) the amp is classic for a reason. Why implement a build with all of these bells and whistles I might not even want or like, and 2) adding these other features exponentially complicates things, especially for a novice builder trying to get through the troubleshooting phase.
Once you build the amp and get it up and running, you can start implementing these other features. If you are creating your own turret board (like I did for my JTM build) you can think ahead and have spaces on your board layout that will be ready to go when you get to the point of trying them out. For example, I have a spot on my board for a split cathode on V1, but will start off with the shared cathode.
I think your best bet for easily incorporated mods would be the switchable NFB, possible switch for shared/split V1 cathode, and maybe a switchable bypass cap on V2a ("lead voicing" maybe?). You could install temporary switches on the side of the chassis (vs front or rear) to avoid any permanent changes to the panels, and once you decide on the ones you like, you can incorporate those on the front or real panel.
Hope this helps, and best of luck with the process! Once you get started on this, it becomes an addiction.
Hello PharmRock. Thanks for the feedback. Very good helpful information. I am considering the JTM45 as well, for a couple of reasons, 1) would be that the chassis design is for a head, which is what I want. 2) The JTM45 was designed as a "guitar amplifier" even though the circuits are very, very similar. Your suggestion to build it very close to stock makes good sense, but if I buy a JTM45 chassis then all the holes are already drilled and if I want to add something I have to work with what space remains. I was considering buying a blank chassis and then drilling and cutting as needed to fit the things that I want in there. But probably its better to go with a chassis that is already made for the job. Seems to plenty of space on the rear to add a few things in the future. I think one of the biggest things that's holding me back at this point is the idea of spending the money to buy the parts to build one, (I don't care about my own labor time) getting finished and for what ever reason just not liking the sound or feel of the end product. I guess knowing that these two amps are considered by many to be the holy grail of guitar amps should provide some solace to me, but there are so many choices in components ie: which brand caps, which type of resistors, what brand transformers, ect ect, that all interact with each other and hopefully come together to produce sound that you love. Thanks again for the feedback. Good information. :bravo1:
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Welcome to the forum!
Here a very handy link: ALL-TIME great information (https://el34world.com/Forum/index.php?topic=23286.msg250136#msg250136)
Thanks uki I will check it out!
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I think one of the biggest things that's holding me back at this point is the idea of spending the money to buy the parts to build one, (I don't care about my own labor time) getting finished and for what ever reason just not liking the sound or feel of the end product.
Reminds me of something I read by Doug here on his site:
"First of all let me start by saying, it is usually more expensive to build an amp from scratch than to just go buy an amplifier. Imagine buying all the parts for an automobile one by one and then putting it all together to make a car. Do you know how to do that? If you don't know how to assemble an automobile from scratch it would be a good idea to attend an automobile mechanics class and start your learning process."
https://el34world.com/projects/scratchbuild.htm (https://el34world.com/projects/scratchbuild.htm)
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Thank you for the feedback. Did you build this as a head unit? Or did you build it as a combo?. Any changes to the original circuit? Other than the different choke? Can you post a sound clip? Or video of you playing thru it? How is the clean sound? vs the driven sound? Does it sound good at lower volume levels, or do you have to crank it pretty loud for it to sound good. Overall are you happy with it? In love with it? Or just okay with it?
Glen
It's Hoffmans 5F6A on a turret board, and it's a head so it was a little fun to make as it's inverted. I converted a Baldwin organ power supply and thats why it has the big iron. Hoffmans board only has two input jacks - normal and bright. Since I play mostly clean I tend to like the bright channel as the normal channel is somewhat dark. I don't know the style of music you play but this bassman sounds good plugged straight in at low volumes which is normal for playing at the casa. I haven't played it loud much at all. I play it through 1x12 or 2x12 and the speakers are all ferrite Celestion 75 Weber 12F150 and an Emminence Tejas Heat. I don't have any vids sorry. Hoffmans board has a bias adjust trim pot already on it. I like the amp but honestly I play my Super Reverb head much more often and it's a Hoffman AB763. I haven't played a JTM45 to be able to compare it to the 5F6A. I am quite happy with the bassman.. The normal chan has sort of a tubular tint to it, maybe that's the EL34 sound and I should probably try some 5881s in it. The bassman and probably the JTM45 are not as clean as the Super thats for sure. You will prolly get better advice on the 5F6A from a perfoming musician than from me.
The reason the turret board in my bassman is inverted is because I built it to be a head in the Marshall style with the tubes standing up no hanging down like a Fender. You can build a Fender circuit and install it in a head cab with no speakers Fender style which is probably what you were thinking of. I don't suggest your first amp build be like mine.
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I installed a triode pentode switch in my Super and I will probably never use it. The difference is not that great and the triode mode sounds a little thin comparably. and not toneful to my ear. I seriously doubt if would be much different in the bassman. Something more useful would be a LarMar PPIMV and/or some switching from fixed bias to cathode bias. Also a switchable cathode circuit on the first amplification stage. The safety diodes can't hurt. Hoffmans board also has the 1 ohm bias sense resistors which are very handy.
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Something more useful would be a LarMar PPIMV
+1 on the LarMar PPIMV. Still new at this, but I've installed this on 2 amps so far and very pleased. Inexpensive, easy, and reversible. If done correctly it introduces no noise/hum. Use one of the speaker jack holes in the back panel to mount the pot.
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MResister—- You did Choke input filter?
Tell me more about this please.
I did it once , the amp goes thud when you turn it on and off.
Did you find a work around for this?
I’ve read a lot about inrush current and choke input filter, but never really found enough info to deal with it.
What’s the secret, can you tell me or point me in a good direction?
Thanks
VT
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GReed01-
I’ve built the 5F6A three times now, and I find it to not really be my flavor.
In my opinion, it has way too much low end. I think it get fame and acclaim because it was the basis for so many great amps that came after it. I get that you wanna do some things to make it different, so did I, three times.
I personally would suggest going a different route. Build plexi or JCM800 if you wanna rock. Build a super or a vibroverb if you want awesome cleans.
Maybe the best place to start is, why do you want to build a bassman? Does it really suite your style of playing, or are you doing it because it’s talked about alot?
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Reminds me of something I read by Doug here on his site:
"First of all let me start by saying, it is usually more expensive to build an amp from scratch than to just go buy an amplifier. Imagine buying all the parts for an automobile one by one and then putting it all together to make a car. Do you know how to do that? If you don't know how to assemble an automobile from scratch it would be a good idea to attend an automobile mechanics class and start your learning process."
Hmmm. Well. I'd really have to compare the cost's to believe that. But that's not the reason why I want to build a tube amp. I'm a builder by nature. I've been building things most of my life. Computers, RC aircraft, Helicopters, guitars, tooling ect. I've been DIY for a lot of things in my life. I want to be able to put together a hand wired tube amp and have it sound amazing! And I'm determined to do so. I'm just trying to be careful and not foolish and just jump on the first idea that crosses my mind. As far as I know there aren't many amp manufacturers around that still hand wire amps. Fender does a few, Marshall also does a few, Soldano at least did when Mike was running the business, I'm not sure now a days. Dave Friedman does. A BE 50 deluxe will set you back 3599.00 plus tax. Do you think it would cost 3600.00 to build it? Possibly, but I doubt it. He has to make a profit, and he has to pay someone to assemble it. Dr Z amps which I know nothing about are supposed to be hand wired. But for the most part, the industry has been relegated to printed circuit boards. My MB Triple Crown is on a printed circuit board. But it seems like we all want vintage stuff out of the 50-60's to some degree. Maybe with a modern twist. I have a set of old RCA 6L6GC power tubes short bottle left from some of my dad's old radio stuff still. I don't know how good they are as I don't have a tube tester, and they stopped having them at the local pharmacy long ago. But they are currently in my Hot Rod Deville biased at 70 mv. They are still working, and I'm not willing to part with them. Mmmmm. I'm rambling on..... I digress.
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I installed a triode pentode switch in my Super and I will probably never use it. The difference is not that great and the triode mode sounds a little thin comparably. and not toneful to my ear. I seriously doubt if would be much different in the bassman. Something more useful would be a LarMar PPIMV and/or some switching from fixed bias to cathode bias. Also a switchable cathode circuit on the first amplification stage. The safety diodes can't hurt. Hoffmans board also has the 1 ohm bias sense resistors which are very handy.
Hmmm. Thank you for sharing that information. I will have to search for that (LarMar PPIMV) as I have no clue what that is or how it works.
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GReed01-
I’ve built the 5F6A three times now, and I find it to not really be my flavor.
In my opinion, it has way too much low end. I think it get fame and acclaim because it was the basis for so many great amps that came after it. I get that you wanna do some things to make it different, so did I, three times.
I personally would suggest going a different route. Build plexi or JCM800 if you wanna rock. Build a super or a vibroverb if you want awesome cleans.
Maybe the best place to start is, why do you want to build a bassman? Does it really suite your style of playing, or are you doing it because it’s talked about alot?
That's the thing, without having ever played thru one I don't know for sure. It certainly has its stature. Marshall copied it for there JTM 45. If I could have it anyway I wanted I would like a 3 channel amp that does amazing clean, great crunch, and smoking high gain. That's why I bought a triple crown, but of the TC 3 channels really I only love the clean channel with the drive set to about 1:00pm and the master at approx 10:00pm. Channel 2 I just cant get a crunch tone that I'm happy with either with my custom shop 59 reissue Les Paul or with my Strat, nor a high gain sound out of channel 3 that I love. There not horrible, but I'm not in love with both those channels. More often that not I play the clean channel which has just a little bit of drive and nice touch sensitivity on the guitar and with varying my playing style I can get lush cleans with creamy upper register notes and leads, and good touch harmonics.
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You may want to listen to some Dumble amp clips. Plenty of info and resources at The Amp Garage (https://ampgarage.com/forum/index.php). Very knowledgeable and friendly people. Good musicians too.
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I’m not sure what kind of spaces you’re planning to play this amp in, but I built a 5F6A about a year ago and it was way too loud to use in my home. Bear in mind a cranked 15w amp can deafen everyone in your house easily, and a 40w amp like a 5F6A will get the police called on you by your neighbors. I couldn’t play mine above about 30% on the dial. I added a master volume and a lead channel but just ended up realizing it was the wrong amp for my needs and I got rid of it. I love the sound of a cranked 5F6A but if I had to do it again I would look at some of the “micro” Bassman designs out there instead if you are after that sound in particular, or one of the many great 15-20w designs that are very popular to build.
Just something to think about - if you don’t already have any amps in this power range, swing by a guitar shop and play one for a few minutes to get any idea of what you’re in for.
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MResister—- You did Choke input filter?
Tell me more about this please.
I did it once , the amp goes thud when you turn it on and off.
Did you find a work around for this?
I’ve read a lot about inrush current and choke input filter, but never really found enough info to deal with it.
What’s the secret, can you tell me or point me in a good direction?
Thanks
VT
The Baldwin organ had this great big choke in the power supply and I used it as the primary input filter at the suggestion of Sluckey who helped me with that build. The PT outputs near 700v and the big choke drops it down into the 400s. I don't know the exact plate V as I haven't been in the amp in years. This amp does not exhibit that symptom, no clunk when turning it on or off. Can't help ya with that.
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You may want to listen to some Dumble amp clips. Plenty of info and resources at The Amp Garage (https://ampgarage.com/forum/index.php). Very knowledgeable and friendly people.
Good musicians too.
Thank so much sluckey. I looked quickly at the forum for some of the videos and sound clips but haven't found much yet that helps. A quick YouTube video search however found this video which was excellent and I would recommend watching.
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Boy that Dumble sounds sweeeeet 👌 100 watt head played at a level that matches the level of the dialog. Unless some editing was done. Just because you have some power available doesn't mean you have to max out the volume and gain controls to get great tone. IMHO.
G. Rees
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Perhaps a 6F6GT power section for the bassman is the ticket!
What would that be, 14 watts or so maybe.
Hmmmm🤔
So many options.
I too am in the process of rebuilding my 5F6A bassman. I had it set up pretty dang good but as others have said , it’s beastly loud. To loud to use at home unless your nearest neighbor is 10 miles away.
Any how. Listen, when you build it,
1. use 1 Meg LINEAR taper pot not audio taper for the volume.
2. Use a 1 watt 6800 ohm tail resistor instead of 10K
3. And use 100k slope resistor instead of 56k.
Connected to one side of that slope resistor, you’ll see two .02 caps, one to the mid and the other to the bass control. Consider changing the bass cap to .1uf.
Another thing to consider is your speaker loud and it’s relation to the negative feed back loop resistor.
The schematic shows 27k, but that is for a 2 ohm speaker load.
If your going to run 4 or 8 ohm speaker loads, you may want to change that value, make it higher.
I’m no authority on what values would be appropriate for a 4, 8, or 16 ohm speaker load but perhaps someone else can chime in.
As far as the three deviations from the schematic listed above, these are well documented as what was actually done on the 5F6A from the factory.
Fender never updated the layout or schematic to reflect these deviations, but that’s what they did.
Now,,, I’m curious,, what transformers will you be using for this build?
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I too am in the process of rebuilding my 5F6A bassman. I had it set up pretty dang good but as others have said , it’s beastly loud. To loud to use at home unless your nearest neighbor is 10 miles away.
Any how. Listen, when you build it,
1. use 1 Meg LINEAR taper pot not audio taper for the volume.
2. Use a 1 watt 6800 ohm tail resistor instead of 10K
3. And use 100k slope resistor instead of 56k.
Connected to one side of that slope resistor, you’ll see two .02 caps, one to the mid and the other to the bass control. Consider changing the bass cap to .1uf.
Another thing to consider is your speaker loud and it’s relation to the negative feed back loop resistor.
The schematic shows 27k, but that is for a 2 ohm speaker load.
If your going to run 4 or 8 ohm speaker loads, you may want to change that value, make it higher.
I’m no authority on what values would be appropriate for a 4, 8, or 16 ohm speaker load but perhaps someone else can chime in.
As far as the three deviations from the schematic listed above, these are well documented as what was actually done on the 5F6A from the factory.
Fender never updated the layout or schematic to reflect these deviations, but that’s what they did.
Now,,, I’m curious,, what transformers will you be using for this build?
Hey Valvetones. The modification that you just outlined are exactly what Rob Robinette lists and shows in his schematic. Take a look here
https://robrobinette.com/5F6A_Modifications.htm Seeing how Fender designed this amp for intended use with the bass guitar, it make sense to me that some changes would be required to make it work out well for guitar.
With regards to transformer I've only looked at 2 thus far, as far as the power amp is concerned. One was a Mercury Magnetics which I can't seem to find the right one at this moment or maybe I made a mistake with regards to the high voltage output number. The other one that seems to fit the bill is a Hammond 290dx https://www.hammfg.com/electronics/transformers/classic/290 I can't find a schematic for this at the moment either, but the specs are listed. Heater current available is only 4 amps though. Which according to Rob is just enough to be able to run a pair of EL34's if desired. Thanks for the feedback, information, and dialogue.
G. Rees
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Good luck on your build G’Rees.
Keep us posted on the outcome and your thoughts.
I’ll check out the link you sent.
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… To loud to use at home unless your nearest neighbor is 10 miles away.
Any how. Listen, when you build it,
1. use 1 Meg LINEAR taper pot not audio taper for the volume.
…
Why linear, wouldn’t a decent smooth audio taper pot will facilitate lower volume use?
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I don't know where you are located, but; here in the USA finding transformers and other components at present time is near impossible. You may be ahead of the game if you buy a used Bassman Reissue. I believe that most, if not all, have Schumacher transformers. The later LTD series have finger jointed pine cabinets with reissue Jensen alnico speakers. The earlier reissues have plywood cabinets (Baltic Birch?) and blue frame Eminence Legend alnico speakers. Either would be a good platform to mod or rebuild using a new circuit board. Buy one and try it out to see if you like the amp without sinking a lot of time and money into a potential white elephant. If you do not like the amp, you can sell it and recoup your money without incurring much, if any, of a loss.
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Good luck on your build G’Rees.
Keep us posted on the outcome and your thoughts.
I’ll check out the link you sent.
Hey there Valvetones. Hope posting the link to the information on Robs site and the confirmation that what you said and he says both agree wasn't offensive to you or anyone else in any way. I'm not 100% committed to building a 5F6A circuit quite yet as I stated in my original post. Still considering and thinking. I wrote an email to Mercury Magnetics last night with regards to the PT. I'll post once they reply. Please share any feedback on your own bassman build. What you like, what you don't, any other changes that you made other than the ones that just mentioned. And if you have time to look at the Hammond PT let me know what you think. Thanks again.
G.Rees
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I don't know where you are located, but; here in the USA finding transformers and other components at present time is near impossible. You may be ahead of the game if you buy a used Bassman Reissue. I believe that most, if not all, have Schumacher transformers. The later LTD series have finger jointed pine cabinets with reissue Jensen alnico speakers. The earlier reissues have plywood cabinets (Baltic Birch?) and blue frame Eminence Legend alnico speakers. Either would be a good platform to mod or rebuild using a new circuit board. Buy one and try it out to see if you like the amp without sinking a lot of time and money into a potential white elephant. If you do not like the amp, you can sell it and recoup your money without incurring much, if any, of a loss.
Hey there 66 strat! Thanks for the feedback. Interesting idea. Certainly worth considering. Could certainly lower your financial liability if it turned out that you just really didn't like the amp. But then again if the circuit ends up needing some mods to make it work for you, you'd have to be pretty careful with your work to be able to return it to stock for resale. Why do you think getting components here in the USA is next to impossible?
G.Rees
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Hey there 66 strat! Thanks for the feedback. Interesting idea. Certainly worth considering. Could certainly lower your financial liability if it turned out that you just really didn't like the amp. But then again if the circuit ends up needing some mods to make it work for you, you'd have to be pretty careful with your work to be able to return it to stock for resale. Why do you think getting components here in the USA is next to impossible?
G.Rees
If you don't like the basic stock amp, why would you go any further? The deeper that you dive into mods, the further under water you will be regarding your investment in the project. Have you ever played a 5F6-A Bassman? They are relatively clean sounding amps until you get up towards the higher end of the volume control. At that point, they are LOUD. They are great sounding amps, but if you are wanting overdrive be prepared for the volume or get an OD pedal. If you are in the US, find one at a Guitar Center near you and play through it.
As to transformers, the supply chain backlog has left vendor inventories depleted. Mojotone does not have any 5F6A or JTM 45 output transformers in stock.
https://www.mojotone.com/amp-shop/electronics/transformers/output-transformers?page=1 (https://www.mojotone.com/amp-shop/electronics/transformers/output-transformers?page=1)
Same goes for power transformers.https://www.mojotone.com/amp-shop/electronics/transformers/power-transformers?page=1 (https://www.mojotone.com/amp-shop/electronics/transformers/power-transformers?page=1)
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Have you ever played a 5F6-A Bassman? They are relatively clean sounding amps until you get up towards the higher end of the volume control. At that point, they are LOUD. They are great sounding amps, but if you are wanting overdrive be prepared for the volume or get an OD pedal. If you are in the US, find one at a Guitar Center near you and play through it.
I have not played thru a 5F6-A Bassman. I didn't see one at my local Guitar Center the last time that I was there. And the last time I looked online at Fender's website currently they produce 3 versions of the Bassman. 2 heads, One that is all tube at 300 watts, One that is hybrid tube and solid state at 800 watts, and a copy of the 59 combo at 45 watts, but it's not hand wired, and I'm not sure at this point what changes have been made to the design. According to Fender's nomenclature a 5F6-A is a 1956 Bassman, which was hand wired at that time. (correct me if I'm mistaken) The combo that they produce would be closest to the 56 design. And I'm due for a trip to GC anyways, been wanting to stop by for that last week or so. So I will go today and take a look, I'll bring my Strat and if they have one I'll plug in and see (which is a great suggestion and I was planning to do that already) who knows maybe I'll get lucky and they do have one on the floor.
With regards to transformers. Hammond makes one that appears to me to fit the bill, and they are available, see prior post. As I've said a few times now I'm not dead set on a 5F6-A amp, but considering one. Also waiting on a return email from Mercury Magnetics with regards to transformers- which I will post the reply when it arrives. Thank you for the feedback, appreciate it.
G. Rees
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1. use 1 Meg LINEAR taper pot not audio taper for the volume.
2. Use a 1 watt 6800 ohm tail resistor instead of 10K
3. And use 100k slope resistor instead of 56k.
Connected to one side of that slope resistor, you’ll see two .02 caps, one to the mid and the other to the bass control. Consider changing the bass cap to .1uf.
As far as the three deviations from the schematic listed above, these are well documented as what was actually done on the 5F6A from the factory.
Fender never updated the layout or schematic to reflect these deviations, but that’s what they did.
That's news to me.
Since the early 90's, I've never read in any book on tube amps (name it, I probably have it) or any tube amp forum about those 'well documented' changes.
There is talk of tweed 5F6a Bassmans actually having the latter .1/.047 caps and not the 2 x .022 caps shown for the TS in the Fender schematics.
A tweed Bassman has no TS tail R, it uses a 25K mid pot.
You can change the slope R from 56K to 100K, but if you do, now your into Brown face 6G series and Black face AB763 series Fender amps. (Not talking about the volume pot taper.)
The 56K TS slope R and 25K mid pot in the TS are a large part of why guys love the old tweed amps. Way less mid scoop than if using the latter 100K and 6K8 R's TS values.
You want mid scoop, AB763 circuits.
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Seeing how Fender designed this amp for intended use with the bass guitar, it make sense to me that some changes would be required to make it work out well for guitar.
No, no, no, it works great with guitar as is!
That's why guitar players were, and still are, playing through the tweed Bassmans back when they came out. And that's why Marshall copied it.
Look at the 5F8a tweed Twin, all circuit values are the same. What Fender did for the 5F6a Bassman was give it a larger PT and OT. That helped keep the power supply a little stiffer, to handle the low bottom end. So it had a stronger/tighter bottom end and stayed a little cleaner/clearer, a little longer across the spectrum. Guys liked the clearer low end.
https://el34world.com/charts/Schematics/files/Fender/Fender_twin_5f8a_schem.pdf (https://el34world.com/charts/Schematics/files/Fender/Fender_twin_5f8a_schem.pdf)
The only thing you might want to change and that goes for any Fender, and many other amps is the preamp K bypass cap values. If your going to be cranking the amp, lower the 25uF to 10uf or 4.7uF. It takes the low end mud out.
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Seeing how Fender designed this amp for intended use with the bass guitar, it make sense to me that some changes would be required to make it work out well for guitar.
No, no, no, it works great with guitar as is!
That's why guitar players were, and still are, playing through the tweed Bassmans back when they came out. And that's why Marshall copied it.
Look at the 5F8a tweed Twin, all circuit values are the same. What Fender did for the 5F6a Bassman was give it a larger PT and OT. That helped keep the power supply a little stiffer, to handle the low bottom end. So it had a stronger/tighter bottom end and stayed a little cleaner/clearer, a little longer across the spectrum. Guys liked the clearer low end.
https://el34world.com/charts/Schematics/files/Fender/Fender_twin_5f8a_schem.pdf (https://el34world.com/charts/Schematics/files/Fender/Fender_twin_5f8a_schem.pdf)
The only thing you might want to change and that goes for any Fender, and many other amps is the preamp K bypass cap values. If your going to be cranking the amp, lower the 25uF to 10uf or 4.7uF. It takes the low end mud out.
The first JTM45 was pretty much a dead nuts copy of the 5F6-A circuit. Key differences were 12AY7 tube in the V1 slot for the Bassman vs 12AX7 for the JTM45 and four 8 ohm Jensen 10 inch alnico speakers wired parallel for the Bassman vs two 16 ohm alnico Celestion Blues wired parallel for the JTM45.
While you're at Guitar Center, see if they have a JTM45 to play through. The amp won't have Celestion Blues but will likely be connected to a cabinet loaded with greenback Celestions. Speakers make a huge difference with this circuit IMO.
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Willabe
If by TS you mean tone stack, you are confused. TS don’t have tail resistors, but Phase Inverters do!
And yes it is well documented, despite the lack of that knowledge in your library.
Here’s some food for thought regarding what you may see in a real 5F6A
https://m.youtube.com/watch?v=tU7wXFFZ08w
Notice that 6.8 k where the schematic shows 10k?
See how the 1960 has linear pots?
There are other images and videos you can check out that will have these same changes.
And as the man said, Rob Robinette has said the same thing.
Now to the builder— if you decide to build a bassman I can almost 100% guarantee that once you have it working, within a week , you will be considering the very simple mods that made the JTM45, The Plexi, and the JCM800.
And even if you like one of those, you will still wish you built a Quieter amp.
I suggest scaling down the power section and using 6v6 or 6F6
As for the transformers, I have enough to build 30 amps.
What do you need, and do you want merit, Stancor, thordarson , or Triad?
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Personally I think the 5F6A has way to much low end. It gets kinda farty distortion when you finally get it to break up.
I’ve gone through and played with the Duncan TS calc and ripped up and rebuild several times now.
This particular time, I’m going to change the cap that feeds the Phase inverter from .02 to something in the PF range, somewhere between .0047 and 250PF. This one cap is the bottleneck for the whole preamp, and looks like a good spot to cut some low end.
What gave me this idea? Last summer I build a 6G16 vibroverb, and it’s glorious, I’m way happier with that than I ever was with the bassman builds, and it feeds the Phase Inverter with a .0005 mfd cap.
50 pico farads yes?
So if that small of a bottle neck works well for this, and many others, perhaps it will suit me better this time around, and is worth experimenting with values to come up with the right stuff, which is subjective of course.
Also, to my ears, cutting the 250mfd cathode cap down to between 2md and 25mfd may be another spot to shave some Low end.
Now I will say the stock circuit has some great cleans, and if that’s what you like, make it so.
I’ll be using 6F6G tubes and will report back.
Do tell us what you decide on and if you plan on changing things after the initial build.
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Hey guys. Understanding Fender's circuit nomenclature is a bit of pain in the $^^%#. I was doing some reading and came upon this on Fender's website which I found helpful : https://www.fender.com/articles/gear/going-low-the-history-of-the-bassman. Pretty good information, hopefully correct.
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Willabe
If by TS you mean tone stack, you are confused. TS don’t have tail resistors, but Phase Inverters do!
And yes it is well documented, despite the lack of that knowledge in your library.
Here’s some food for thought regarding what you may see in a real 5F6A
https://m.youtube.com/watch?v=tU7wXFFZ08w
Notice that 6.8 k where the schematic shows 10k?
See how the 1960 has linear pots?
There are other images and videos you can check out that will have these same changes.
And as the man said, Rob Robinette has said the same thing.
Now to the builder— if you decide to build a bassman I can almost 100% guarantee that once you have it working, within a week , you will be considering the very simple mods that made the JTM45, The Plexi, and the JCM800.
And even if you like one of those, you will still wish you built a Quieter amp.
I suggest scaling down the power section and using 6v6 or 6F6
As for the transformers, I have enough to build 30 amps.
What do you need, and do you want merit, Stancor, thordarson , or Triad?
Wow!!! How super cool is that? I had just finished watching part one of the same video just now!!! :smiley: Hey Valvetones, that's super nice of you to offer that help on the transformers. You know quite a few people now have mentioned on this topic, the concern with how LOUD!!!! this amp would be (Rated at approx 40 watts) right? My Deville 4 x 10 is rated at 60 watts if I remember correctly. My MB Triple crown is rated at 50 watts. I play both of them in my little bedroom studio> Do they get loud? Yea they do if you crank the volume knob up a little ways. But I don't play either one of them on 1-2. Bedroom level on the Fender clean channel usually 3, up to 4 and that's loud enough for sure unless for some reason I just want to rattle the windows or piss off my neighbors who are all actually pretty cool and know that I play. MB clean channel is about 1:00pm on the gain, 12:00pm on the channel volume, and 11:00am on the master volume. Sounds great and doesn't hurt your ears. Also the MB isn't as searing on the high notes as the fender FWIW. An Lar-mar Master volume might be a good idea, I need to read up more to understand how that works, and how it affects the tone. And finally the offer to help with me with some transformer needs, is really super kind of you. I will definitely keep that in mind, although brand to brand I have no clue what the better or best choice might be>
G.Rees
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While you're at Guitar Center, see if they have a JTM45 to play through. The amp won't have Celestion Blues but will likely be connected to a cabinet loaded with greenback Celestions. Speakers make a huge difference with this circuit IMO.
[/quote]
Well I had planned to get over to Guitar Center this afternoon, but it just didn't happen. I had a few other things that I needed to take care of. I will make it over there tomorrow!!!!
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Speakers make a huge difference with this circuit IMO.
Speakers make a huge difference in most builds. Once an amp is up and bug-free, start with speakers, lots of speakers, it's easy, it's productive, you won't burn holes in your polyester pants since you don't need to solder.
Once you find "the speaker", now you're ready to tweak Tone.
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Willabe
If by TS you mean tone stack, you are confused. TS don’t have tail resistors, but Phase Inverters do!
And yes it is well documented, despite the lack of that knowledge in your library.
Here’s some food for thought regarding what you may see in a real 5F6A
https://m.youtube.com/watch?v=tU7wXFFZ08w
Notice that 6.8 k where the schematic shows 10k?
See how the 1960 has linear pots?
There are other images and videos you can check out that will have these same changes.
And as the man said, Rob Robinette has said the same thing.
Now to the builder— if you decide to build a bassman I can almost 100% guarantee that once you have it working, within a week , you will be considering the very simple mods that made the JTM45, The Plexi, and the JCM800.
And even if you like one of those, you will still wish you built a Quieter amp.
I suggest scaling down the power section and using 6v6 or 6F6
As for the transformers, I have enough to build 30 amps.
What do you need, and do you want merit, Stancor, thordarson , or Triad?
Wow!!! How super cool is that? I had just finished watching part one of the same video just now!!! :smiley: Hey Valvetones, that's super nice of you to offer that help on the transformers. You know quite a few people now have mentioned on this topic, the concern with how LOUD!!!! this amp would be (Rated at approx 40 watts) right? My Deville 4 x 10 is rated at 60 watts if I remember correctly. My MB Triple crown is rated at 50 watts. I play both of them in my little bedroom studio> Do they get loud? Yea they do if you crank the volume knob up a little ways. But I don't play either one of them on 1-2. Bedroom level on the Fender clean channel usually 3, up to 4 and that's loud enough for sure unless for some reason I just want to rattle the windows or piss off my neighbors who are all actually pretty cool and know that I play. MB clean channel is about 1:00pm on the gain, 12:00pm on the channel volume, and 11:00am on the master volume. Sounds great and doesn't hurt your ears. Also the MB isn't as searing on the high notes as the fender FWIW. An Lar-mar Master volume might be a good idea, I need to read up more to understand how that works, and how it affects the tone. And finally the offer to help with me with some transformer needs, is really super kind of you. I will definitely keep that in mind, although brand to brand I have no clue what the better or best choice might be>
G.Rees
If you have a Deville, turn the master volume all the way up, the drive down, and then use the channel volume to set your overall volume. That would be an approximation of how the Bassman is going to behave. It will be loud and clean.
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...
1. use 1 Meg LINEAR taper pot not audio taper for the volume.
2. Use a 1 watt 6800 ohm tail resistor instead of 10K
3. And use 100k slope resistor instead of 56k.
Connected to one side of that slope resistor, you’ll see two .02 caps, one to the mid and the other to the bass control. Consider changing the bass cap to .1uf.
...
As far as the three deviations from the schematic listed above, these are well documented as what was actually done on the 5F6A from the factory. ...
That's news to me.
Since the early 90's, I've never read in any book on tube amps (name it, I probably have it) or any tube amp forum about those 'well documented' changes.
One of Gerald Weber's books mentions the different capacitor & slope resistor values in the tone stack. It says there were 3 different ways 5F6-A Bassman tone stacks were configured, even though only one is shown on the schematic.
Else, you have to go talking to folks who own the original tweed amps & have seen A LOT of them. Some Fender models had notable deviations fro the schematic, others didn't.
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Given Fender's high model turnover in the 50s and 60s, that Bassman model was in production for a long time, nearly 3 years. Leo is reported to have liked to tinker and tweak things. I get the impression that the Sept 57 5F6-A documentation, whilst applying to earlier batches, may not be 100% accurate for the entirely of the production cycle. Hence the modern RI 59 Bassman and its various differences (eg tone stack, presence / LTP) to the Sept 57 circuit. ie it was a reissue of the '59 Bassman design, rather than the '57.
Perhaps in an ideal world, the documentation would have kept up with the changes, eg 5F6-B, 5F6-C, perhaps it did but never made its way into the public domain, but most probably the changes, if documented at all, were in the form of hand annotations to the factory floor copy.
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If by TS you mean tone stack, you are confused. TS don’t have tail resistors, but Phase Inverters do!
Coming on kind of strong for a new member, don't you think so? :think1:
You could have wrote that a little gentler and a just touch more respectful in response. :laugh:
Yes I meant tone stack and some TS's do have tail R's.
Fender brown/black face amps that do not have a mid range pot have a 6K8 tail R that the TS stands on. It's the mid range set R. That R is the tail of the TS. Look at Vox top boost and latter Gibson GA77 amps (Gibson copied the Vox top boost TS). The mid range set R is in || with the bass pot, the TS does not stand on the mid set R, so it is not a tail R.
Amps that have a TS with a mid pot don't have the tail R, but you could, and guys do, put a 6K8 R under a 25K or 50K mid pot so turning the mid pot to zero, you have the standard Fender mid value. Turn up that mid pot and you start removing the mid range scoop.
For clarity, it would have been helpful if you would have said/wrote LTPI in your post. I saw 6K8, 10K, common Fender TS tail R and mid pot values and thought TS.
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Willabe,
Perhaps, abit strong, I guess I read your post as coming on abit strong and just wanted to point out that these changes are known.
Certainly not looking to hurt any feelings. Just an amp thread. And only trying to be helpful.
Thank you for the additional detail about the (other ) tail resistor.
Cheers!
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And yes it is well documented, despite the lack of that knowledge in your library.
https://m.youtube.com/watch?v=tU7wXFFZ08w (https://m.youtube.com/watch?v=tU7wXFFZ08w)
No, turns out I have it in Webers 1st book, just forgot. :laugh:
I must have dismissed it at the time of reading it years ago when he said; Two .02s for the bass cap and middle cap with a 56K ohm slope resistor are the values generally regarded as the best sounding because the bass is clearer."
Personally I think the 5F6A has way to much low end. It gets kinda farty distortion when you finally get it to break up.
3. And use 100k slope resistor instead of 56k.
Connected to one side of that slope resistor, you’ll see two .02 caps, one to the mid and the other to the bass control. Consider changing the bass cap to .1uf.
Considering Webers comment of which TS values give clearer bass in the 5F6/5f6A Bassmans, maybe you should reconsider going back to the 2x .02/56K slope R values? :undecided: And maybe lower the 1st preamp tube K bypass cap from 250uF down to 10uF of 4.7uF?
Weber probably had his hands in dozens of original 5F6/5F6A Bassman already by the time he wrote that 1st book. He would have known by then.
See below;
From Webers 1st book; A Desktop Reference of Hip Vintage Guitar Amps, 1994, The Definitive 4x10 Bassman, page 52;
"You never know what you will see in a 5F6 or 5F6A for tone caps. The treble cap was always a silver mica 250pF ; however, I know of three different sets of vales used for the middle and bass caps and the slope resistor. Fender's schematic shows two caps (.02mfd) and a 56K slope resistor in the schematic; however, a .1 mfd bass cap and the .02 middle cap with a 100K slope resistor were very common. Though I have never seen one, there are a few 5F6 series Bassmans that used a .1 mfd bass cap and a .047 middle cap with a 100K ohm slope resistor for the tone circuit. Two .02s for the bass cap and middle cap with a 56K ohm slope resistor are the values generally regarded as the best sounding because the bass is clearer."
Never disputed that there are 5F6/5F6A Bassman with different TS values out there, I said there was talk of that. I know HBP has brought it up before.
What I am disputing is that it's well documented. Now that HBP said it's in a Weber book, I remember it, sort of. (I read that in the mid 90's, that's a long time ago. :laugh:) So I got the book out and read it just now.
I wouldn't call a couple of paragraphs in 1 tube amp book "well documented." Documented yes, well documented no. And that link you posted, yes he has a couple of real tweed Bassmans, but he's talking about talking with a "Texas amp builder" in his comments, so he's clearly drawing from Weber.
There are other images and videos you can check out that will have these same changes.
And as the man said, Rob Robinette has said the same thing.
For all we know, Robinette got it from that same book as many others could have too.
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Here’s some food for thought regarding what you may see in a real 5F6A.
So the 5F6/5F6A Bassmans with the Fender schematic values in the TS aren't real tweed Bassmans? :think1:
Note that Weber writes the ".1 mfd bass cap and the .02 middle cap with a 100K slope resistor were very common." But doesn't write their just as common/just as many or there's more of those than the 2x .02/56K TS. And the 3rd TS value version, he writes there are a few but only the 5F6, not the 5F6A.
So it seems of the 3 TS value versions, the 2x .02/56K R were most common.
I think it's more like HBP wrote;
Else, you have to go talking to folks who own the original tweed amps & have seen A LOT of them.
Some Fender models had notable deviations fro the schematic, others didn't.
It's known by guys who had them in their hands and opened them up. Not because it's been documented in tube amp books.
If the other TS values were the 'secret sauce' of a 5F6/5F6A Bassman we'd be talking about it a LOT here as a TS option and it would be in most tube amp books and in tube amp companies clones of tweed bassmans.
Marshall copied Fenders 2x .02/56K TS values, and stayed with those values. They even lowered the slope R to 33K on some amps, opposite of going up to 100K slope R. Then many copied Marshall. Luck of the draw that Marshall had a 2x .02/56K to copy? :dontknow:
And the reissue Bassmans are bright and hash sounding. I would not be copying those amps. :w2: :laugh: Some gut them and put in a eyelet/turret board and new PT to get the dcv's down, then they like/love them.
At that time, tweed amp series, Leo was still in the pretty early stages of evolving his amps. We know he did switch to the TS values found in a few of the 5F6 Bassmans, .1 mfd bass cap and a .047 middle cap with a 100K slope R, with the brown/blackface amps. But we also know that besides experimenting he would use different values at times that he had in stock just to get the orders out the door. Could have been a little of both? :dontknow:
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Willabe,
Perhaps, abit strong, I guess I read your post as coming on abit strong and just wanted to point out that these changes are known.
Certainly not looking to hurt any feelings. Just an amp thread. And only trying to be helpful.
Thank you for the additional detail about the (other ) tail resistor.
Welcome to the forum. :icon_biggrin:
Very happy to see you so excited about tube amps, just try not to nip at us old dogs? :icon_biggrin:
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…
And as the man said, Rob Robinette has said the same thing.
…
Rob has kindly provided a lot of well drawn layouts, compiled ideas for mods, builds etc, and hosted The Trainwreck Pages, on his site.
He’s also written a lot of text, lots of explanations for how stuff works.
A lot of people seem to have found it helpful, and he’s got a lot of people enthused to make a start at mods and builds, but I find too many mistakes, errors / misapprehensions and opinion / speculation stated as fact, for me to suggest it as a reference source. In the way that the Aiken or valve wizard sites can be.
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Glad to share the passion for great audio with you all.
Thank you.
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:m12 Hello Everybody!!!!!! Boy this post has warmed up a bit!!!!! So very grateful for everyone here who has contributed to this topic. Thank you all of very much. Willabe, pdf64, valvetones, HotBluePlates, TitaniumValhalla, and everyone else. So much here to respond to. But if I sit here at the computer and type, I won't make it over to Guitar Center today, and I promised I would. Looking for a Bassman or JTM45 to plug into. I have plenty to write in response to the most recent post's and I will, but let me catch with up you guys later in the evening. Again thanks to all for the amazing feedback, and information.
G. Rees
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I got an email back from Jeff Guzman at Mercury Magnetics concerning the power transformer for this 5F6A circuit. Here's what he said
"Hey Glen,
The closes thing I have to that at the moment is the FTBP-59-M2.
I attached the wiring diagram for reference.
Please let me know what you think.
Thank You,
Jeff Guzman
Hmmmm. I wanted the pdf to show the diagram.....
Let me know if there is a way to make the diagram show in the post, so people don't have to download it to view please.
Now bearing in mind that I'm not an electrical engineer, or a talented amp builder, comparing this transformer to the specs I can see that it doesn't meet the HV requirement, should be 325-0-325vac. Bias voltage is over spec at 60 vac. 6.3 v filament @ 8 amp (plenty) and 5 volts for the rectifier tube @ 4 amps (good) So...... Is this an acceptable option for the bassman. Here I need your guys skills, my best guess would be NO. Thoughts... Maybe you could trim back the bias from 60 to the needed 50 with some resistors, or caps or both, but I can't see how to increase the HV from 315 per leg 630 total to the needed 650. Please advise. Also I previously posted a link to Hammond's PT 290DX which does seem to meet the specs on paper, but I haven't found a schematic for. Does anyone have some feedback on this transformer, or suggestions.
Thank you
G. Rees
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Alrighty. Well I made it over to my local Guitar Center this afternoon. Amp selection was pretty limited. This particular store is on the smaller side, and even in it's best moment's doesn't have a huge amount of inventory... I checked and no Bassman to be found new or used. No JTM-45. No hand wired amps at all. On the Fender side they did have a few, and on the non fender side a handful more. So not wanting my trip to be wasted, I played thru 4 different amps. The first one was the little yellow hot rod blues jr. 15 watts. 2 12ax7's and 2 el84 power tubes. Not too bad, actually had reverb if I remember correctly. No real clean sound. Everything has a little crunch to it, and more so as you turned up the volume, as expected, sounded like a tiny little amp though 2) Fender Deluxe Reverb amp, 40 watts, Jensen speaker. This sounded pretty good, fuller, not tiny sounding, cleans were nice and sweet, reverb was touchy, smallest movement of the dial resulted in big changes to amount of reverb, no master volumes, no drive channel. Would expect you would have to really crank the amp up to get a little power tube breakup out of it. 3) Fender Hot Rod Deluxe 40 watts. 6L6 power section with reverb. Sounded similar to my Hot Rod Deville with maybe a touch better sounding drive channel and was advertised as such. Cleans were decent, and drive channel was okay, nothing to write home about, but not bad by any means. The last amp I plugged into was new to me and it was a BlackStar HT VENUE SERIES Club 40MkII. 40 watts again, 1 x 12" speaker 2 12ax7's and 2 el34's, this was a pretty cool little amp. Designed and engineered in the United Kingdom, where it's actually built I don't know, but had some cool features, line out, usb recording, digital reverb, fx loop, and some different voicing options on both the front and back panel. The clean tones were actually very nice, and with a little dip switch you could change between American Clean, and British Clean, the reverb was very good and not touchy with regards to the dial, another little dip switch and you channel 2 voicing with a channel volume and master volume, (same for clean channel as well) and another little dip switch for 2 different levels of drive. The drive channels were actually pretty decent (better than Fender's IMHO) but not Friedman or Soldano kind of good either. But really pretty respectable given the price point which was 999.00 Of all 4 of the amps I would give the best clean tone to the Fender Deluxe with the 6v6 power section, as far as a crunch tone and higher gain type of sound I would have to say that the BlackStar sounded best to my ears. And the blackstar was very close to the Fender Deluxe in clean. Fender was just a bit warmer and maybe rounder sounding likely due to the 6v6 power section as compared to the el34 in the BlackStar. Did any of this help me???????? Not much really. I also wanted to say that for the longest time I have been running 6L6's in my amps, both the Fender Deville and in the Mesa Boogie triple crown 50. Recently I changed out the 6l6"s in the MB and tried a set of JJ's EL34II which I have had on hand for quite some time. I have a little stash of tubes, here's a quote from Eurotubes concerning these particular tubes
" The JJ EL34II prototypes came to us in September of 2014 for testing and we were all amazed that JJ could come up with yet another variant that has it's own sound and distinct place in the already heavily populated EL34 family! The EL34II's are fuller sounding than the standard EL34 but not as "in your face" and aggressive as the JJ E34L. If aggressive, tight and punchy is what you want the E34L is King. The EL34II is a perfect choice for players who love a traditional EL34 sound but need to fill out the low mids and low end without losing any upper mid and high end crunch or definition. They are very warm and sweet sounding!"
The Triple Crown has a little switch on the back to switch the bias between el34 type tubes, and 6l6 type tubes. I'm really quite happy with the sound. Cleans are still very nice and warm, big and 3d sounding, and depending on pick attack I get a nice little ????? I wouldn't say crunch exactly, but maybe a little more driven when you dig in, good harmonic content as well. They seem to better bridge the gap between clean and driven. So in considering the 5f6a circuit I would want the ability to run El34's and other tube types, a bias pot will be a necessity, and enough heater current at least 4 amps would also be a requirement for the PT.
One last thing, I asked the associate helping me to check and see if there's any store close to me 50 miles that has a Bassman LTD on the floor to check out. She checked and told me no one has one in stock. I didn't pursue the matter further, I was kind of running out time.
G. Rees
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Speakers make a huge difference with this circuit IMO.
Speakers make a huge difference in most builds. Once an amp is up and bug-free, start with speakers, lots of speakers, it's easy, it's productive, you won't burn holes in your polyester pants since you don't need to solder.
Once you find "the speaker", now you're ready to tweak Tone.
LOL. Polyester Pants huh? That's funny. Once I get an amp put together, I'll have to do some more research and try and pin down what speakers will be likely to work well with the intended amp design. Seeing as how I'm not Rockefeller, I'm the other fella :laugh:
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The only thing you might want to change and that goes for any Fender, and many other amps is the pre amp K bypass cap values. If your going to be cranking the amp, lower the 25uF to 10uf or 4.7uF. It takes the low end mud out.
Appreciate that recommendation. Wouldn't that be considered a modification though? Or was that something that Fender maybe did on a few of them that just didn't get documented?
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1. use 1 Meg LINEAR taper pot not audio taper for the volume.
2. Use a 1 watt 6800 ohm tail resistor instead of 10K
3. And use 100k slope resistor instead of 56k.
Connected to one side of that slope resistor, you’ll see two .02 caps, one to the mid and the other to the bass control. Consider changing the bass cap to .1uf.
As far as the three deviations from the schematic listed above, these are well documented as what was actually done on the 5F6A from the factory. ...
Since the early 90's, I've never read in any book on tube amps (name it, I probably have it) or any tube amp forum about those 'well documented' changes.
One of Gerald Weber's books mentions the different capacitor & slope resistor values in the tone stack. It says there were 3 different ways 5F6-A Bassman tone stacks were configured, even though only one is shown on the schematic.
Else, you have to go talking to folks who own the original tweed amps & have seen A LOT of them. Some Fender models had notable deviations fro the schematic, others didn't.
[/quote]
Thank you for posting Hot Blue Plates. Good information. Great dialogue here in these post's.
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Given Fender's high model turnover in the 50s and 60s, that Bassman model was in production for a long time, nearly 3 years. Leo is reported to have liked to tinker and tweak things. I get the impression that the Sept 57 5F6-A documentation, whilst applying to earlier batches, may not be 100% accurate for the entirely of the production cycle. Hence the modern RI 59 Bassman and its various differences (eg tone stack, presence / LTP) to the Sept 57 circuit. ie it was a reissue of the '59 Bassman design, rather than the '57.
Perhaps in an ideal world, the documentation would have kept up with the changes, eg 5F6-B, 5F6-C, perhaps it did but never made its way into the public domain, but most probably the changes, if documented at all, were in the form of hand annotations to the factory floor copy.
I think you might be right on the money. No one else besides the manufacturer needed the notes. And they were probably kept quite close to the breast to protect their designs.
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And yes it is well documented, despite the lack of that knowledge in your library.
https://m.youtube.com/watch?v=tU7wXFFZ08w (https://m.youtube.com/watch?v=tU7wXFFZ08w)
No, turns out I have it in Webers 1st book, just forgot. :laugh:
I must have dismissed it at the time of reading it years ago when he said; Two .02s for the bass cap and middle cap with a 56K ohm slope resistor are the values generally regarded as the best sounding because the bass is clearer."
Personally I think the 5F6A has way to much low end. It gets kinda farty distortion when you finally get it to break up.
3. And use 100k slope resistor instead of 56k.
Connected to one side of that slope resistor, you’ll see two .02 caps, one to the mid and the other to the bass control. Consider changing the bass cap to .1uf.
Considering Webers comment of which TS values give clearer bass in the 5F6/5f6A Bassmans, maybe you should reconsider going back to the 2x .02/56K slope R values? :undecided: And maybe lower the 1st preamp tube K bypass cap from 250uF down to 10uF of 4.7uF?
Weber probably had his hands in dozens of original 5F6/5F6A Bassman already by the time he wrote that 1st book. He would have known by then.
See below;
From Webers 1st book; A Desktop Reference of Hip Vintage Guitar Amps, 1994, The Definitive 4x10 Bassman, page 52;
"You never know what you will see in a 5F6 or 5F6A for tone caps. The treble cap was always a silver mica 250pF ; however, I know of three different sets of vales used for the middle and bass caps and the slope resistor. Fender's schematic shows two caps (.02mfd) and a 56K slope resistor in the schematic; however, a .1 mfd bass cap and the .02 middle cap with a 100K slope resistor were very common. Though I have never seen one, there are a few 5F6 series Bassmans that used a .1 mfd bass cap and a .047 middle cap with a 100K ohm slope resistor for the tone circuit. Two .02s for the bass cap and middle cap with a 56K ohm slope resistor are the values generally regarded as the best sounding because the bass is clearer."
Never disputed that there are 5F6/5F6A Bassman with different TS values out there, I said there was talk of that. I know HBP has brought it up before.
What I am disputing is that it's well documented. Now that HBP said it's in a Weber book, I remember it, sort of. (I read that in the mid 90's, that's a long time ago. :laugh:) So I got the book out and read it just now.
I wouldn't call a couple of paragraphs in 1 tube amp book "well documented." Documented yes, well documented no. And that link you posted, yes he has a couple of real tweed Bassmans, but he's talking about talking with a "Texas amp builder" in his comments, so he's clearly drawing from Weber.
There are other images and videos you can check out that will have these same changes.
And as the man said, Rob Robinette has said the same thing.
For all we know, Robinette got it from that same book as many others could have too.
Excellent information all the way around. Thanks so much for sharing Willabe!!!!. To me with the exception of the power transformer, these are all very minor changes in cap and resistance values, or a pot type or value change that made the difference between a great sounding Bassman and a not so great sounding Bassman.
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And as the man said, Rob Robinette has said the same thing.
…
Rob has kindly provided a lot of well drawn layouts, compiled ideas for mods, builds etc, and hosted The Trainwreck Pages, on his site.
He’s also written a lot of text, lots of explanations for how stuff works.
A lot of people seem to have found it helpful, and he’s got a lot of people enthused to make a start at mods and builds, but I find too many mistakes, errors / misapprehensions and opinion / speculation stated as fact, for me to suggest it as a reference source. In the way that the Aiken or valve wizard sites can be.
Hmmm. Okay. Well there is a lot of information available on Rob's website. Do you see errors or other problems with regard to what he wrote about this particular amp. If there are some concerns that you have, could you be specific and list them and what the error or problem is? I would certainly appreciate knowing if something is incorrect. And were all human after all.
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Hey. Just found this at Amp Parts Direct. https://shop.amppartsdirect.com/collections/apd-custom-by-heyboer/products/copy-of-blackfront-super-reverb-power-transformer-apd-8073h-by-heyboer-transformers-upgrade-of-40-18073 That looks like right on the money, in stock, not too expensive, and its a Heyboer. Please have a look and let me know what you think.
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…Do you see errors or other problems with regard to what he wrote about this particular amp…
It’s now a long thread to trawl through, a link to it would handy :icon_biggrin:
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...To me with the exception of the power transformer, these are all very minor changes in cap and resistance values, or a pot type or value change that made the difference between a great sounding Bassman and a not so great sounding Bassman.
The difference is NOT night and day between the different TS cap and slope resistor values. Depending on your ears, you can hear it but it's a fine tuning thing at best.
Just because Fender tried different TS values doesn't mean the changed values were needed to make it a 'great sounding' amp. It was and still is fine with the original TS values.
Marshall copied the original values and look how that turned out. Guys love Marshall for the fuller mids.
Guys love the tweed amps for the fuller mid range. Putting a 100K in place of the 56K slope R scoops the mids.
And changing the volume pots taper from audio to linear doesn't change the amps tone, it just changes how fast the volume goes up as you turn the pot. I'd use an audio taper for the volume.
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…Do you see errors or other problems with regard to what he wrote about this particular amp…
It’s now a long thread to trawl through, a link to it would handy :icon_biggrin:
No problem. Here you go.
https://robrobinette.com/5F6A_Modifications.htm
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NOT[/i] night and day between the different TS cap and slope resistor values. Depending on your ears, you can hear it but it's a fine tuning thing at best.
Just because Fender tried different TS values doesn't mean the changed values were needed to make it a 'great sounding' amp. It was and still is fine with the original TS values.
Marshall copied the original values and look how that turned out. Guys love Marshall for the fuller mids.
Guys love the tweed amps for the fuller mid range. Putting a 100K in place of the 56K slope R scoops the mids.
And changing the volume pots taper from audio to linear doesn't change the amps tone, it just changes how fast the volume goes up as you turn the pot. I'd use an audio taper for the volume.
Understood Willabe. Appreciate your input sir.
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If looking for the tweed bassman sound at lower volumes consider the venerable Little Wing by Geezer. Geezer has not been around the forum for a while but I think his demo track is still live. Worth a listen https://el34world.com/Forum/index.php?topic=562.0 (https://el34world.com/Forum/index.php?topic=562.0)
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If looking for the tweed bassman sound at lower volumes consider the venerable Little Wing by Geezer. Geezer has not been around the forum for a while but I think his demo track is still live. Worth a listen https://el34world.com/Forum/index.php?topic=562.0 (https://el34world.com/Forum/index.php?topic=562.0)
Thanks for posting pullshocks. I took a listen, very nice indeed. I wanted to look at the schematic and layout diagram .sch files, but do not have an application for opening that type of file. Please advise what program to use.
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https://el34world.com/Forum/index.php?board=12.0
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Jschem works on Windows and Mac-OS.
Available at http://jschem.bplaced.net or, I think you can get it on git-hub also.
It's the best free schematic program for Mac that I have found -- there may well be something better, I don't know.
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You may want to listen to some Dumble amp clips. Plenty of info and resources at The Amp Garage (https://ampgarage.com/forum/index.php). Very knowledgeable and friendly people. Good musicians too.
This is well worth looking into.
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…Do you see errors or other problems with regard to what he wrote about this particular amp…
It’s now a long thread to trawl through, a link to it would handy :icon_biggrin:
No problem. Here you go.
https://robrobinette.com/5F6A_Modifications.htm
That's too open ended :help:
The page goes on forever, and there's numerous links to other pages, which themselves have links.
Up to the 'list of mods' heading, the text and schematic seemed ok, though on the layout, the 'safety ground' chassis connection position may imply the use of a PT mounting bolt to also serve as this. Which would be bad practice.
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Here is a PDF of the original by Geezer.
Tubenit created a number of variants, including one with reverb, that would also be worth checking out.
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That heybor will work, but I’d reach out to them directly and ask what the EXACT specifications are of the transformers because there’s not enough info available to make the best decision. The current handling specs of the HV and the 5 and 6.3 volt windings are not listed.
If the 6.3 winding is capable of handling EL34s (they consume more than a 6l6) then you could put those in and rebias and run the 34s.
However, remember, (and I’m gonna sound like a dic here) that you can’t really make a great determination of whether the EL34s sound better than a 6l6 just by swapping the tubes. Because the 34s want a 3.3k primary impedance in the OT and the 6l6s want a 4K primary.
To compound the issue further, you can really run either tube at a veriety of different loads but may not get the best sound or best use of power depending on the impedances you may try.
Very few people have enough time and access to output transformers to test this, but I can say from experience that lower impedances are punchier and clearer and higher are more distorted with less output.
I’m sure I’ve opened a can of worms.
Even the loading suggested by the data sheets tends to be higher than what is typically used in guitar amps.
For instance, for a 6l6 it’s 5k in class A and 6.6k in AB1. Yet you see 4K pretty often in AB1 in guitar amps, well, fenders anyway.
For a 6v6 it’s between 8 and 10k in the data sheets, depending on class of operation but in a deluxe fender used 6.6k. Which may be why Neal Young thought 6l6s in his deluxe sounded so good. I could be wrong though as I’m not 100% sure the tweed deluxe OTs were 6.6k.
But the AB763 blackface deluxe Reverb’s were 6.6k.
Anyway,, back to the PT.. You should be aware of the voltages you are liable to see based on the Amperage of the winding.
Let’s say your 6.3 winding was rated at 8 amps (as you suggested on the other PT you considered) and your total filament draw is 2.7amps, well since your not using all 8 amps, the voltage will be higher, probably above 7 volts. Now you can go a little higher and a little lower on the filaments, but there is a limit, and higher filament voltage will wear the tubes out faster. You don’t want to put your nice telefunken or Amperex tubes in an amp that has 7.2 volts on the filaments due to an extremely over rated winding for a given project.
Point is, you want to get as close to original specs as possible. The bassman used a GZ34 that needs 2amps at 5volts. But I bet most transformers will have a 3 amp winding. Probably not as critical on the rectifier because only being off by 1 amp on that winding won’t yield a huge difference in the 5 volt winding. It might be 5.2 or something.
But watch out on the 6.3 volt winding.
To use EL34s and 6l6s you will actually WANT it to be slightly beefier than original specs, but not to much.
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If you build your amp right, and use good parts, all modern amplifiers will sound like children’s toys.
Your ears well then be spoiled and you will go to Guitar center much much less.
Or, so is my prediction. I personally do not enjoy the harsh sterile sound of any modern fender.
As for the blackstar, I’m in the digital distortion sucks, natural overdrive is awesome camp.
My ears are most definitely spoiled though, and it actually has its down side. I can’t tell you how many times someone has said “this tone is awesome “ playing some modern junk, and they look at me for agreement and validation and I just roll my eyes and hang my head low, lol. Most people that have never played an old amp or built an old circuit, will never know what they are missing. It’s a “ignorance is bliss”kinda thing.
Once you commit and get it built, I’ll be curious to see what your ears cause you to think in regards to the above statements.
Also, I wanna know all the details, what kind of speakers, what transformers, what type of resistors, what type of capacitors, what brand of tubes, etc etc, you end up using to put this together. Because there’s the recipe, and then there’s the ingredients that will all play there part in the final result.
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Hey ValveTones, thanks for posting, I was hoping someone would look at the referenced transformer. I see looking at the diagram that it shows, 7amps for the 6.3 volt winding, and 4 amps for the 5 volt winding. No current rating listed for the HV though. Nor any impedance values. I'll reach out and see if I can come up with more information. Anything else I should be asking about. It is referenced for a 5f6a Bassman for what its worth.
G.
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If you build your amp right, and use good parts, all modern amplifiers will sound like children’s toys.
Your ears well then be spoiled and you will go to Guitar center much much less.
Or, so is my prediction. I personally do not enjoy the harsh sterile sound of any modern fender.
As for the blackstar, I’m in the digital distortion sucks, natural overdrive is awesome camp.
My ears are most definitely spoiled though, and it actually has its down side. I can’t tell you how many times someone has said “this tone is awesome “ playing some modern junk, and they look at me for agreement and validation and I just roll my eyes and hang my head low, lol. Most people that have never played an old amp or built an old circuit, will never know what they are missing. It’s a “ignorance is bliss”kinda thing.
Once you commit and get it built, I’ll be curious to see what your ears cause you to think in regards to the above statements.
Also, I wanna know all the details, what kind of speakers, what transformers, what type of resistors, what type of capacitors, what brand of tubes, etc etc, you end up using to put this together. Because there’s the recipe, and then there’s the ingredients that will all play there part in the final result.
I hear ya, my ears are picky too. I haven't heard a modern Fender that sounded amazing yet. Getting a sweet clean is ify. As far as it goes the little blackstar was an all tube amp. Not solid state, just made in china. :dontknow:
Answer me this. Why are so many people of the mind set that its better to have a 5-15 watt amp and dime it vs a 40 watt amp ran at 20-30% Is there any truth to the idea that tube amps just sound better maxed out or near maxed out? I get the power tube distortion concept, but Really?????
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Well,, if glorious overdrive that won’t be heard over a drummer is what your after, then yes 10-15 watts is great.
There’s so much going on with that.
Sure the power tubes are distorting but so is the speaker if it’s a low wattage speaker.
And the output transformer is saturating , sometimes because it’s undersized, which adds compression.
This 63 vibroverb I build does that all really really well and is able to keep up with drums. I purposely changed the tone stack around to reduce bass and raise upper mid range. I used a 25 watt output transformer and two original cone Jensen P12N speakers.
The old ones were rated at 18watts pretty sure.
So 25 watt OT 3.3k pri with EL34s, 36watts of speaker handling capacity in an amp that’s suppose to put out 35-40 watts. It’s my greatest build to date.
I mention all this only to point out that if you buy a modern transformer but the voltages are higher than the state, and you get 4 speakers that are over rated in watts, and you get the big iron OT 40 watt modern thing, your going to end up with a very clean amp that might not break up the way you want. Now you could build a little champ or Vox ac4 to get your living room overdrive happening, and build a bigger amp to serve as a pedal platform or play in a band sorta thing. Anyway, big amps break up too and sound FANTASTIC if you choose the right parts and pieces.
Have I talked you out of a bassman yet? Lol
Wish I could post some pics of the vibroverb on here but I’d have to have someone walk me through it Barney style and hold my hand like I’m a child every step of the way.
No idea how to resize pics on an iPhone.
Let me ask you these questions ,
1. what’s your favorite guitar to play, 2. do you prefer single coils or humbucker
3. name me three of your favorite guitar players.
4. Do you play in a band?
5. Do you prefer pedals or do you like to get the grit from the amp?
Answer me these and I’ll point you in the right direction, and offer my opinions if you want them.
VT
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...Wish I could post some pics of the vibroverb on here but I’d have to have someone walk me through it Barney style and hold my hand like I’m a child every step of the way. No idea how to resize pics on an iPhone. ....
No Barney here!!
(https://memegenerator.net/img/instances/51908602.jpg)
ForumHow-Tos (https://el34world.com/Forum/index.php?board=2.0)
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Let me ask you these questions ,
1. what’s your favorite guitar to play, 2. do you prefer single coils or humbucker
3. name me three of your favorite guitar players.
4. Do you play in a band?
5. Do you prefer pedals or do you like to get the grit from the amp?
Answer me these and I’ll point you in the right direction, and offer my opinions if you want them.
VT
Hey VT!!!! I'll walk you through resizing photos if you'd like and getting them posted. NO Problem.. With regards to your questions.
1) I grew up playing a Les Paul, and for me for the longest time it was an LP or nothing, recently within the last year I started playing a strat. I have 2 of them, and a 2009 Custom Shop 59 reissue LP. I'm growing into prefering the Strat actually. For a couple of reasons, 1 its not nearly as dark sounding as the LP, and 2 it's not nearly as heavy as the LP. So at the moment I play the Strat almost exclusively.
2) Geez there's a lot in that category.. Jimi Page, Stevey Ray Vaughn, Joe Bonamassa. All the music out of the 80's and some out of the 90's as well.
3) Not currently. In the past I played sometimes with others, never really a band per se, lugging equipment over to the drummers pad got old real quick, for the most part now days, I play at home, either my own stuff, sometimes a little cover stuff, and lately just jamming along to backing tracks and playing around with learning DAW's and how to record stuff. Keeps me amused and is fun.
4) I don't own a single pedal!!!. The only effect unit I have is a Gen 1 Line 6 Pod, recently been using that in the effects loop on my MB triple crown for a little delay which sounds nice to me. A tube amp that could produce an excellent clean, crunch, and high gain would be awesome, and the Triple Crown has 3 channels that are supposed to do that, but in reality the only channel that sound great is the clean channel, channel 2 - 3 need work. I'd like to play thru the new Friedman BE-50 deluxe. Sounded pretty damn good on the review at Sweetwater. No one anywhere close to me has one in stock.....
And of course I want your opinions..... You have written quite a bit in this thread, and shared lots of really good information.
Yes please, and thank you.
G.
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Let me ask you these questions ,
1. what’s your favorite guitar to play, 2. do you prefer single coils or humbucker
3. name me three of your favorite guitar players.
4. Do you play in a band?
5. Do you prefer pedals or do you like to get the grit from the amp?
Answer me these and I’ll point you in the right direction, and offer my opinions if you want them.
VT
Hey VT!!!! I'll walk you through resizing photos if you'd like and getting them posted. NO Problem.. With regards to your questions.
1) I grew up playing a Les Paul, and for me for the longest time it was an LP or nothing, recently within the last year I started playing a strat. I have 2 of them, and a 2009 Custom Shop 59 reissue LP. I'm growing into prefering the Strat actually. For a couple of reasons, 1 its not nearly as dark sounding as the LP, and 2 it's not nearly as heavy as the LP. So at the moment I play the Strat almost exclusively.
2) Lately the single coils, but those humbuckers on the Les Paul do sound good when ran thru a high gain channel. For me though, I just can't listen to the real high gain stuff for long, it seems to wear out my ears. Sounds pretty awesome for 5-20 minutes though.
3) Geez there's a lot in that category.. Jimi Page, Stevey Ray Vaughn, Joe Bonamassa. All the music out of the 80's and some out of the 90's as well.
4) Not currently. In the past I played sometimes with others, never really a band per se, lugging equipment over to the drummers pad got old real quick, for the most part now days, I play at home, either my own stuff, sometimes a little cover stuff, and lately just jamming along to backing tracks and playing around with learning DAW's and how to record stuff. Keeps me amused and is fun.
5) I don't own a single pedal!!!. The only effect unit I have is a Gen 1 Line 6 Pod, recently been using that in the effects loop on my MB triple crown for a little delay which sounds nice to me. A tube amp that could produce an excellent clean, crunch, and high gain would be awesome, and the Triple Crown has 3 channels that are supposed to do that, but in reality the only channel that sound great is the clean channel, channel 2 - 3 need work. I'd like to play thru the new Friedman BE-50 deluxe. Sounded pretty damn good on the review at Sweetwater. No one anywhere close to me has one in stock.....
And of course I want your opinions..... You have written quite a bit in this thread, and shared lots of really good information.
Yes please, and thank you.
G.
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Gen 1 Line 6 Pod,
This is not mine, mine is clean and in great shape for being 20 years old. LOL
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I wanted to share a link that I ran across while looking at Weber Speakers. They have a couple of video's of their speakers in a Bassman. The link is https://www.tdpri.com/threads/5f6a-build-summary.641338/ Guy built a Bassman, Weber speakers. Handful of mods from Rob's site, and has his guitar teacher play thru it. Check it out, looks like he's playing straight into the amp. Very nice build write up as well, and some of the problems he encountered while building it.
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“ I probably was biting off more than I should for a first amp project and added to the complexity of the build with all of the mods I added.”
:laugh: :l2:
Wha’d I tell ya! He modded the heck out of it!
Sounds great doesn’t it? But not a straight up bassman sound.
So yeah I mean, if you like the bassman as a platform and wanna plexi or 800 it up, yeah sure it’ll sound nice.
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PRR
LMAO
I didn’t think so :l2: :l2:
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Alright so
1. You are preferring the strat these days for several reasons, namely it’s not as dark.
So don’t build a dark amp (like a bassman). Build a brighter amp and you may switch back to the LP because it won’t seem so dark anymore.
Remember though, you don’t want late 70s fender twin ice pick treble either. So choose wisely.
Lower voltage power transformers lend them selves to the de-icing , because it will allow you to bias the tubes to draw more current , which is a browner sound even with a bright circuit. So consider running somewhere between 290-340 volts on the plates.
Beyond that and you have to bias the output section colder and that increases headroom , you loose harmonic content because the amp won’t give up the goods.
Of the fender 30-35 watt variety, vibroverb’s, band masters, tremolux’s pro’s and supers. These circuits from the brown or blackface days have that bright enough but not ice picky thing going on.
I’m the 15-20 watt fender category deluxe Reverb’s, Princeton’s etc are sort of the same as for the treble registry. Of course, each circuit may have more or less, but generally speaking they are comparable in the high frequency department, of course the little amps will break up quicker.
You know, a vox ac15 or ac30 has some good chimes going on in the treble department.
Marshall’s are ultra bright until you crank them up, then that power section breaking up sort of makes it ok.
The Gibson Falcon is one great sounding beast, it’s worth looking into.
There are valcos and such etc that might suit your style as well. The sun doesn’t rise and set on fenders only you know!
Ok maybe it kinda does, lol, but!! I think that’s mostly because the layouts are easier to follow, making building one easier to comprehend.
I highly recommend checking out other things you might like to build besides fenders , not because they aren’t great, they are, but because there are other great things out there too, and hopefully you get what you want the first build around. Lest you catch the amp bug and have to build 20 more before you can decide , like me😒
I think an amp that does all three things great like you said will be challenging. Usually you sacrifice in one area to gain in another. That’s why marshals sound thin and weak when played clean, and why fenders sound muddy when cranked.
It’s really hard to have it all in one amp.
I tend to believe what you said about Friedman though. Dave is a cool guy, and smart as a wizards book.
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2. Jimi , Stevie, and Joe all have pretty opposite sides of the tonal spectrum covered.
I see now why you want an amp that does it all! Lol.
Since your not into pedals really (Which, Good for you, me neither)
I’d say you might think about which of those three sounds you like the most , and go that way, or better said, if you could only choose one sound to grow closer to, which would it be? It worth considering. Amp parts aren’t cheap, and building them requires a lot of effort, so you want to choose your direction carefully.
Let’s leave out the part about how SRV , Joe, and Jim could probably all play their guitars through a peavey practice amp and still get their tone.
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Oops I’m outta order, last one was 3.
My bad.
For 2 I’d say single coils sound best through fenders for clean and vox for grit and chime. Just my opinion though, ymmv.
Humbuckers also sound great through fenders and vox, for the same reasons, and actually humbuckers through a vox circuit sound awesome clean and crunchy. Not so much on the crunchy through a cranked fender. More muddy than a single coil and that’s already bad enough.
Now #4 is key, you hate lugging things around and your not in a band.
Sounds like a good reason to build a 15-20 watt amp.
Also sounds like a GREAT reason to build a head / speaker cab instead of a combo.
You’ll have two pieces to transport if you ever do, but it’ll be way easier making two trips, rather than a huge heavy bassman 4x10 cab with the weight of the Amp in it too!
Final thoughts, if it were me (which it’s not)
I’d spring for building a 15-28 watt head with four el84s. Make it cathode biased and put a switch in it that changes cathode resistor values, that way you can pull out two el84s and run the other two for 15-18 watts.
(I want to play loud with my new band)
-I’m glad I built this with four power tubes.
(I want to play at home with the amp breaking up and not get the cops called)
-I’m gonna pull the two outside el84s and flip the cathode resistor switch.
Now ironically , I pick that as the best fit for your circumstance, but it’s kinda the best catch all, and not going to get you to close to the sound of Joe, Jim or steve… but if any probably Jimmy.
So if I where to be specific in one direction only I’d say
If you want the Stevie direction
Vibroverb
If you want the Joe direction
Do that bassman
If you want the Jimmy direction
Start thinking outside the box because fenders, Vox’s, and Marshals
are not the way. He played a Supro and at some point got into super Beatles.
Now remember, there are others who might point you in other directions , and their reasoning and opinions are equally as valid . These are all just ideas to get you thinking about what direction you might want to go.
Only you can decide.
Please do tell us what direction that may end up being.
As for the pictures, lol, if you feel up to it. I’d be interested to know how to do it on an iphone.
Spoiler alert, I tried once briefly and gave up.
Good luck my friend.
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as they say, opinions are like belly buttons...everybody's got one! (or some variation of that saying)....here's mine...
my most recent build is a 50W Plexi. anything I've thrown at it...vintage low wind single coils, high output Seymour Duncan HBs, P90s...they all sound good. sometimes you need to twist some knobs or roll back the guitar volume. Does it do scooped Fender DR cleans?...no...but it still puts out a beautiful clean tone.
One of the best sounds I've gotten was a strat through the Plexi...awesome blues rock. roll back the guitar volume and it cleans up and sounds glorious.
Remember too that SRV played everything from Dumbles to a Vibroverb to a Marshall. A lot of the tone is in the hands of these players. They could play through a valve junior and sound great.
15-20 watts is fine for gigging. For larger venues you'll be mic'ing the cab anyways. Last time I played out anywhere was about 10 years ago and used a Marshall 1974 clone (18w) and it covered the classic rock tones perfectly with plenty of "chime". Throw a boost in front and it screams. Mic'd the cab and the sound guy is happy.
15-20 watts at home, turned up past 4 or 5, will get the cops called unless you live out in the middle of nowhere. and even then you'll have to be at home by yourself or else the wife and kids will probably be yelling at you to turn it down! The only reason I built the Plexi (and currently the JTM45) is because I've never had or played through an amp like that and just wanted to build one. And I got one of those reactive load thingys that let me crank it and keep the volume manageable.
I started with the simple stuff first...18 watt lite, and went from there. All of the classic circuits sound great and cover a lot of ground. Just be prepared that no matter the first one you build, it probably won't be your last!
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Wow. Holy moly, boy you sure did some typing. Hopefully not on your iphone VT. First of I want to say to you. THANK YOU!!!!! for investing as much time as you have in this topic. I also want to say Thank you to all the members who have also contributed their time to this topic. I should clarify at this time that I have not yet committed to any one given design. Also I should clarify that I'm still considering the Bassman 5F6-A circuit. From the very beginning of this topic I stated this
" Considering what amp to build. I'm looking for lovely 3d clean and a little grit when I dig in with the pick. Some harmonic overtone depending on my playing dynamics. I've been considering the Bassman circuit with a few mods that Rob lays out. I need a multi output OT so I can use it with my existing cabinet. I want adjustable bias so I can run different power tubes. The modification to the power tube sockets so I can run el34 power tubes if desired. An adjustable feedback loop circuit. Backup diodes on the rectifier tube, and possibly diode rectification thats swichable. Pentode / triode switching on the power tubes for a 1/2 power mode. Possibly voicing a lead channel.
I though at the time of writing that, that copying the original version of the circuit may very well leave me wanting with regards to tone..
As such the JTM 45 is almost identical in design, and from there the plexi is fairly close in design. I though that a handful or Rob's mods provides options in tone that the 5F6A circuit doesn't have. With the option to run different tube types, an adjustable feedback loop, Likely a master volume control, maybe diode rectification as an option, and voicing a lead channel, it seemed to me that might make for a pretty good medium sized amp. It's not easy to choose an amp design to build for me at least, due to not being able to hear it in person, and say "man that sounds great and feels good" I was never intending to build a combo amp. Too freeking heavy. I have a combo amp. Fender Hot Rod Deville 4 x 10" likely very similar to the bassman combo. It's sitting here next to me as I type. And it's heavy. I used a dolly to bring it inside from the garage. I've looked in the forum at the video clips area, hoping that some of the builders here would post video's of the their builds, and them playing thru the amps. I posted one video so far of me playing the triple crown on the clean channel. There's really not a lot posted there to help. There's more in the sound clip area of the forum, but some of the links are no longer good a few do work, but I'm not exactly sure what I'm listening to. Is the guitar plugged straight into the amp? Any effects on? Whats the volume level? ect ect. On my Hot Rod Deville on the clean channel, playing notes on the upper registar of the neck is ear piercing at anything above 3 on the volume. My Triple Crown has a better sounding clean channel and doesn't pierce the ear at the same volume levels, and the high's are creamier sounding, not as ???? Biting??? if that's the right choice of words. I really want to avoid the rabbit hole of chasing amp designs trying to get sweet sounds out of an amp. That sounds like a money pit for sure.. It's not that I hope to only build one amp and find greatness, that's unrealistic, I'll probably build a few, but I want to really like the end result of my money and labor........
G.
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as they say, opinions are like belly buttons...everybody's got one! (or some variation of that saying)....here's mine...
my most recent build is a 50W Plexi. anything I've thrown at it...vintage low wind single coils, high output Seymour Duncan HBs, P90s...they all sound good. sometimes you need to twist some knobs or roll back the guitar volume. Does it do scooped Fender DR cleans?...no...but it still puts out a beautiful clean tone.
One of the best sounds I've gotten was a strat through the Plexi...awesome blues rock. roll back the guitar volume and it cleans up and sounds glorious.
Remember too that SRV played everything from Dumbles to a Vibroverb to a Marshall. A lot of the tone is in the hands of these players. They could play through a valve junior and sound great.
15-20 watts is fine for gigging. For larger venues you'll be mic'ing the cab anyways. Last time I played out anywhere was about 10 years ago and used a Marshall 1974 clone (18w) and it covered the classic rock tones perfectly with plenty of "chime". Throw a boost in front and it screams. Mic'd the cab and the sound guy is happy.
15-20 watts at home, turned up past 4 or 5, will get the cops called unless you live out in the middle of nowhere. and even then you'll have to be at home by yourself or else the wife and kids will probably be yelling at you to turn it down! The only reason I built the Plexi (and currently the JTM45) is because I've never had or played through an amp like that and just wanted to build one. And I got one of those reactive load thingys that let me crank it and keep the volume manageable.
I started with the simple stuff first...18 watt lite, and went from there. All of the classic circuits sound great and cover a lot of ground. Just be prepared that no matter the first one you build, it probably won't be your last!
Great Post. Thank you!!!!! Can you please post a video of you playing your amp with a little demo of the setting and sounds on both the amp and guitar. Really would be helpful to watch. And you are 100% right, a talented player, can an old Silvertone sound pretty damn good.
G.
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Okay VT here we go. Adding photo's with an Iphone, open up app store, search "image resizer", find "Image Size" download app. Open app. Top left of the screen right below the ads bar. There's a picture icon. Press it. Provide access to all photo's. Select the photo you wish to adjust the size on. Photo opens, select "Choose" bottom right of screen. On the bottom of the picture it will show how big the files is in MB or KB. In the box directly above the picture in the middle you can type in a value, right above that box is a listing for how you want to adjust the image size ie: pixel, <or=pixel, mm, cm, inch. Select <or= to pixel. Depending on the size of the picture your working with type a value into the box in the middle. I used 1000 for an image that was 2.3MB. At the bottom of the screen it will show you a conversion ie: the original size and the resized image size if you wish to proceed. Play with the value to get the size image you want. Bottom left there's an arrow pointing down. If you press that it will resize the image and save it to your photo's. It also preserves the original photo. Now you have 2. On iphone when viewing photos if you drag the image upwards it will reveal the meta data, which includes the image size. Just like right clicking a image file and selecting properties on a windows computer does. Okay, so now you have an image the has been resized to be under the 2048kb file size specified by Doug's website. When you want to post a picture somewhere click the "Attachments and other options" link and under that were it says Attach file, select "choose file" then when iphone pop ups options, select camera roll. Select the resized image that you want. If your only doing one image select post. (make sure if you have text to type that first, before selecting attachments. You can then press post and your picture should show up. If you have multiple files, 4 attachments is the max per post, select more attachments after you do the first one, but remember the total files size for the images can not exceed 3072kb, and the individual image size can not exceed 2048kb. Hopefully this helps and your able to post some images. I for one want to see what you have going on!!!!!!
Best Regards
G.
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As far as switchable rectification, you could just wire it up for a GZ34 rectifier and when you want SS, use one of these: https://tubedepot.com/products/solid-state-rectifier (https://tubedepot.com/products/solid-state-rectifier)
I've installed the LarMar PPIMV in my Plexi. Its very easy to do (and undo) and if done correctly is very "unobtrusive" to the tone.
I have never done the pentode/triode thing, but based on the the stuff I've read, people aren't too keen on the tone in the triode setting. But if you install a PPIMV, why would you need the triode option?
For voicing a lead channel...that's basically the same as splitting the cathode on V1 of a JTM, and maybe decreasing the value of the Normal channel cathode bypass cap. In other words...sort of like a Plexi (1987, 1959).
I'm still new to this, but being able to run EL34s as well as other octal tubes like 6V6, 6L6 or KT66 may present a bigger design challenge, as you might have to change the bias supply as well as worrying about the OT primary impedance. I'd imagine if you want the option to run 6V6 or one of its bigger brothers in the same amp, you may have to drop the voltage quite a bit unless you exclusively use JJ6V6's which are designed to run at a much higher plate voltage.
Selectable NFB seems like an easy mod to do, but once you get a suitable NFB resistor in there, the presence control will be able to cover a lot of ground by itself.
I'm very much still the new kid on the block here, so take my recommendations with a grain of salt. Many of the things you are considering I have also considered and implemented or decided not to go with in my most recent builds.
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Alright, let’s see if this works. Let’s see if Barney was right.
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Heck YEAH!!!
You da man :worthy1:
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PharmRocks post is awesome.
A plexi is a thing of beauty.
I’m not so hot on the attenuater thingy dealy’s. I had one once. It does lower the volume, and kills the tone. Maybe I got a junky one. I know the one Dr. Z makes is essentially the same thing as Ken Fischer’s of Trainwreck. That one may be better. I got some Elcheapo one for $40 and hated it.
So you could indeed go the plexi route, get a 6600 ohm OT with multiple secondaries 4,8,16.
Put the secondaries on a 3 way rotary switch. Assuming an 8 ohm speaker load, when running two 6v6 set the secondary on 8 ohms for 6.6k.
When running two EL34, use the 4ohm secondary for a 3.3k primary.
When running 6l6s your looking for 4K but choose either 6.6k or 3.3k, probably the 6.6 would be best but 3.3 will be loader and punchier, although you may get some ghost notes.
I’d have to look at the data sheets, but I think in triode mode the required impedance for a given tube may change, probably lower would be my guess.
Go to Google and type in Franks Electron Tube data sheets and start looking at those. I’d suggest looking at multiple manufacturers data sheets for the same tube. I kinda always preferred the GE data sheets, but RCA, Tung-sol, Sylvania, they are all worth looking at.
When you start getting into euro tube data sheets like the EL34 , you’ll notice a big difference in the way they are laid out, and if it bothers you, remember the 6CA7 is the American equivalent and so you may find better looking and reading data sheets that way. Sometimes there is a bit more information or better operational characteristics suggestions from one data sheet to the next.
Thumb through them and consider the information carefully.
Frank’s is a wealth of information. A close second would be an RCA receiving tube manual.
Man I kinda want you to build a plexi now, lol
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Cool, cool, and super cool!!!! So glad it worked for you VT. Now were talking. Plexi hmmm..... They were coveted for sure. Pharmrock. Can you please post pictures of your plexi, and upload a video of you playing thru it. VT Please upload a video of you playing thru one of your amps that your in love with the sound. I need to hear. By the way your photos are awesome. Great looking amp. Nice work buddy!!!! Man those are some good size transformers. Is one of those the choke???? Holy cow.
G.
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Cool, cool, and super cool!!!! So glad it worked for you VT. Now were talking. Plexi hmmm..... They were coveted for sure. Pharmrock. Can you please post pictures of your plexi, and upload a video of you playing thru it. VT Please upload a video of you playing thru one of your amps that your in love with the sound. I need to hear. By the way your photos are awesome. Great looking amp. Nice work buddy!!!! Man those are some good size transformers. Is one of those the choke???? Holy cow.
G.
I'll see about sound clips and pics, not sure about a video as I would need to do all the youtube stuff.
Check out the clips made by our forum's host here: https://el34world.com/schematics.htm#Hoffman_Plexi_6V6
Its a 6V6 rather than EL34 but definitely does the classic Plexi tones
Johan Segeborn's channel on Youtube is awesome, and in this video he compares a Marshall vs Fender on clean tones:
Fender Super Reverb vs. Marshall 50W Plexi (1987x):
Go to around the 4 minute mark to see how the Plexi cleans up by rolling off the guitar volume on a strat
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Here's a clip of one of the best clean tones I have ever heard. It helps that this player knows what he is doing:
Original '59 Fender Bassman Amp - YouTube (https://www.youtube.com/watch?v=Y0r1kVXSX3Q)
There is a feedback component than is happening because of his proximity to the amp.
But, just WOW.
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It helps that this player knows what he is doing
:laugh:
amps are only as good as the operator
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It helps that this player knows what he is doing
:laugh:
amps are only as good as the operator
One of the main things I have learned from YouTube is that I am nowhere near as good as I once thought I was.
I keep getting older and the bar keeps getting higher.
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Here's a clip of one of the best clean tones I have ever heard. It helps that this player knows what he is doing:
Original '59 Fender Bassman Amp - YouTube (https://www.youtube.com/watch?v=Y0r1kVXSX3Q)
Thanks for posting SG - Ive viewed that vid before but everytime it just blows me away.. what tone! Only thing close to it that I've ever heard is a 72 Super Reverb totally recapped with brand new 1028Ks in it. Teh SR didn't have that kind of bass response going on though.
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Here's a vid of '59 bassman with a reissue '59 Les Paul to get an idea of hummers through it.
and the vid following it
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You may find this info useful.
https://www.youtube.com/watch?v=tU7wXFFZ08w&t=8s (https://www.youtube.com/watch?v=tU7wXFFZ08w&t=8s)
He has numerous videos on his channel of both a 1960 Bassman and a 1959 Bassman. He is totally obsessed with everything Hendrix, which IMO is a GOOD thing.
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Here's a vid of '59 bassman with a reissue '59 Les Paul to get an idea of hummers through it.
and the vid following it
Sounds great, but there is no stage or studio the average person has access to where they can crank a 5F6A, so to use that as an example of the tones you're going to get out of it on a daily basis is not really realistic.
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Here's a vid of '59 bassman with a reissue '59 Les Paul to get an idea of hummers through it.
and the vid following it
Sounds great, but there is no stage or studio the average person has access to where they can crank a 5F6A, so to use that as an example of the tones you're going to get out of it on a daily basis is not really realistic.
It is a perfect example of what to expect from the amp. They are LOUD amps. The amps are TOO LOUD for the average bedroom player. But that is a matter of the wrong amp for the wrong venue. Something on the order of 1 to 5 watts would be a better match. Why build/buy a 40 watt amp if you can't play it at a volume where they come into their own. I've owned/played several 40 to 60 watt Fenders. None really start sounding good until you're at least up to 4 or 5 on the volume dial. At that point they are all LOUD.
Edit. FWIW I always loved the sound of a screaming Detroit 6-71 Diesel. I used to haul hay/slop/and cow stuff for a farmer in an old COE GMC with a 6-71. Truly fun to drive, with an absolutely glorious sound. However, they would be HIGHLY FROWNED UPON today as a daily driver.
Example of 6-71 Diesel; however, not in a COE Jimmy truck.
https://www.youtube.com/watch?v=v0I8hYKqGsA (https://www.youtube.com/watch?v=v0I8hYKqGsA)
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they would be HIGHLY FROWNED UPON today as a daily driver.
:l2:
not where I live :icon_biggrin:
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Shooter - not where I live either. :icon_biggrin: so invest in an attenuator.
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they would be HIGHLY FROWNED UPON today as a daily driver.
:l2:
not where I live :icon_biggrin:
I DO NEED to move. I'm thinking off-grid, maybe West Texas.
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Check out this:
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Cool, cool, and super cool!!!! So glad it worked for you VT. Now were talking. Plexi hmmm..... They were coveted for sure. Pharmrock. Can you please post pictures of your plexi, and upload a video of you playing thru it. VT Please upload a video of you playing thru one of your amps that your in love with the sound. I need to hear. By the way your photos are awesome. Great looking amp. Nice work buddy!!!! Man those are some good size transformers. Is one of those the choke???? Holy cow.
G.
Thanks! Yes one is the choke. It’s a 250 mA swinging choke and it is set up the way fender did it in the tweed twin. Usually the choke only handles the supply to the screens, but in this case, the current of the whole circuit goes through it. Originally I had intended to use it as a choke input filter so I could draw some serious current, but, as luck would have it, the vibrato does not work if the power section is biased for glory, so I’m stuck at 40mA per tube, and just ran the choke like the tweed twin does. Plenty of other stories about could’ve been but didn’t work with this circuit. However, some of my endeavors worked out splendidly.
As for the video post, lol, that would require someone to walk me through it Barney style, and hold my hand like a little child every step of the way!
Lmao
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Cool, cool, and super cool!!!! So glad it worked for you VT. Now were talking. Plexi hmmm..... They were coveted for sure. Pharmrock. Can you please post pictures of your plexi, and upload a video of you playing thru it. VT Please upload a video of you playing thru one of your amps that your in love with the sound. I need to hear. By the way your photos are awesome. Great looking amp. Nice work buddy!!!! Man those are some good size transformers. Is one of those the choke???? Holy cow.
G.
Thanks! Yes one is the choke. It’s a 250 mA swinging choke and it is set up the way fender did it in the tweed twin. Usually the choke only handles the supply to the screens, but in this case, the current of the whole circuit goes through it. Originally I had intended to use it as a choke input filter so I could draw some serious current, but, as luck would have it, the vibrato does not work if the power section is biased for glory, so I’m stuck at 40mA per tube, and just ran the choke like the tweed twin does. Plenty of other stories about could’ve been but didn’t work with this circuit. However, some of my endeavors worked out splendidly.
As for the video post, lol, that would require someone to walk me through it Barney style, and hold my hand like a little child every step of the way!
Lmao
I need video. You can do it. Easy peasy. Do you have a YouTube account?
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I have three 5F6A Bassmans in various forms/conversions. I had to add MV's to control the volume and still get the amp response/feel I needed. I think that's already been mentioned once already but not much discussion on it. To me that makes it workable in any room and situation. Platefire
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I have three 5F6A Bassmans in various forms/conversions. I had to add MV's to control the volume and still get the amp response/feel I needed. I think that's already been mentioned once already but not much discussion on it. To me that makes it workable in any room and situation. Platefire
Hey there. Thanks for posting on this thread. Well you must like the circuit if you have built 3 of them. A master volume control was definitely on this list of things to include when contemplating this build. Also the fact that the circuit is so close to a jcm45, and a plexi, is attractive. What's different about the 3 versions that you have? Can you post a video for me please of YOU playing thru YOURS in the video clips section of this forum. I would really appreciate that.
G. Rees
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G,Rees
What kinda microphone did you use when you recorded yourself playing on the backing track?
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G,Rees
What kinda microphone did you use when you recorded yourself playing on the backing track?
Whats up VT :m8 :m8. No mic used. Recorded with my old iPhone and the video file was dropped into Reaper.
G. Rees
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I just wanted to mention that there are quite a few free to try (DAW)'s digital audio workstation out there. All of them have a learning curve to be able to use. But with watching a few intro videos you can be up and running pretty quickly. I'm currently using Reaper, and its free to evaluate, and if you like it, very cheap to purchase at 60.00. Here's the link to Reaper for anyone interested
https://www.reaper.fm/download.php
G.
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Also wanted to mention that smartphones these days do a pretty darn good job recording video and audio. IPhone for sure. I don't have an android phone for comparison. But the specs on all the phones these days are impressive. You can upload your videos to your YouTube channel and share your video here at the forum. I sure would love to see what you've built and hear how it sounds. Please show off a little of your labor of love with the rest of us.....
G.
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“ Please show off a little of your labor of love with the rest of us.....
G.”
I have every intention of doing that.
Might be awhile, but it’s coming.
Stay tuned.
Pun intended :icon_biggrin:
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“ Please show off a little of your labor of love with the rest of us.....
G.”
I have every intention of doing that.
Might be awhile, but it’s coming.
Stay tuned.
Pun intended :icon_biggrin:
Will do! looking forward it for sure.
G.
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Grees01
I was thinking about my builds, actually I have four variations of 5F6A. Three in the form of heads and one combo.Two conversions of old PA Heads, A Dukane, A Bogen CHB-50, scratch built head Marshall 2204 Head(Plexi) and a Modified Pignose GV-40 Combo.
I'm not sure I could be helpful by offering a clip/video of my playing because what already been presented is light years ahead of my playing. I will say this regarding my MV suggestion. I think a large part of the original 5f6A beauty was in the combination of that old original set up running through that 4-10 cab without the MV caused the power tubes to distort when you turned it up loud enough.That was big part of the sound. Of course it had to be turned up pretty loud to reach clipping. With a MV turned down(the power tube not working hard) and the preamps tube turned up, your not going to get the same feel, thickness and tone as you hear in those previous clips. On the other hand the 5F6A has a great clean sound also and that's what I mostly use and use my pedals for boost, OD and Dist. I set my pre vol around 11:00 O clock and my MV at 8:00 O clock to where my sound is mostly clean with just a little clip with my guitar vol full up. Anything more is pedals. As you see the power tubes are not getting into the action much with this setting. So I just wanted to make you aware of this with my MV suggestion.
My first amp build was a modified version of the 5F1/5F2 Champ/Princeton Combo I built in 2001 with the help of a internet friend of mine Casey4s. Here 21 years latter with the help of the Hoffman Forum, I am just now getting all my greenhorn mistakes cleared up to where it really sounding good these days. I think it's good to start small and not over-whim yourself on the first build. Platefire
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My first amp build was a modified version of the 5F1/5F2 Champ/Princeton Combo I built in 2001 with the help of a internet friend of mine Casey4s. Here 21 years latter with the help of the Hoffman Forum, I am just now getting all my greenhorn mistakes cleared up to where it really sounding good these days. I think it's good to start small and not over-whim yourself on the first build. Platefire
I started by adding a tone control to a Valve Junior. Did a couple of Valve Junior conversions, then built an 18W Lite (which is an awesome amp and fairly "simple"), then gradually increased the complexity to where I am now (Plexi, JTM45). Just speaking for myself, there is no way I would've felt comfortable starting out my amp-building journey with the JTM45, especially with several "options".
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My first amp build was a modified version of the 5F1/5F2 Champ/Princeton Combo I built in 2001 with the help of a internet friend of mine Casey4s. Here 21 years latter with the help of the Hoffman Forum, I am just now getting all my greenhorn mistakes cleared up to where it really sounding good these days. I think it's good to start small and not over-whim yourself on the first build. Platefire
Starting with something small and simple is certainly a great suggestion, and makes very logical sense. The problem for me is that I don't want to invest money and labor into an amp that I'm going to end up not liking and not using. I have a Fender Hot Rod Deville 4 x 10 sitting here that I bought many years ago back, in excellent condition, and I just don't very often it at. The sound is not bad. It's 60 watts. A good bit too loud at above 3 on the master volume, but aside from the volume level, I just really don't care for the tone anymore. It has a kind of a piercing type quality to the clean channel that's hard to listen to for long. It's not very 3d sounding even with some reverb turned on, But it was what I used back in the day before I bought my Triple Crown. I haven't personally heard a great sounding small 10-25 watt, single speaker amp to this day. I really wish you would post some video of yours. You don't have to be some super good guitar player for their to be value in the listening to the video. Thanks for sharing on this topic and for the information.
G.
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I started by adding a tone control to a Valve Junior. Did a couple of Valve Junior conversions, then built an 18W Lite (which is an awesome amp and fairly "simple"), then gradually increased the complexity to where I am now (Plexi, JTM45). Just speaking for myself, there is no way I would've felt comfortable starting out my amp-building journey with the JTM45, especially with several "options".
I understand where your coming from. For sure. I don't have any doubt with my ability to assemble the "amp" from the mechanical perspective. Where I'm at a loss is understanding how and why things work the way that they do. I don't have good understanding of how the circuit works. I can read and follow the circuit, and build as designated in the design. But what does that get me? Maybe a great sounding amp, depending on what I choose as a design, and the components ect ect. At the same time it leaves me pretty lost if I'm trying to understand why a certain value of resistor, or capacitor or a particular way of wiring a portion of the circuit influences the way it works or sounds. So I'm reading, and studying, and trying to learn how, why, where, what, ect ect. In that regards I could build a champ circuit or a JTM45 circuit, but still lack in understanding the above. I'd rather invest time and money into something that I'm likely to love when finished. I'd like to hear your 18 watt lite. Please post video. Your Plexi build looks fabulous. Please post video asap.
G.
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Sounds great, but there is no stage or studio the average person has access to where they can crank a 5F6A, so to use that as an example of the tones you're going to get out of it on a daily basis is not really realistic.
It is a perfect example of what to expect from the amp. They are LOUD amps. The amps are TOO LOUD for the average bedroom player. ...
You're both right, but I agree more with TitaniumValhalla that the average player will never turn a tweed Bassman loud enough to distort, absent master volume or attenuator/reamper/load-box.
I played an acquaintance's 1958 Bassman in an airplane hangar on ~7, with a 20 or 30ft cord. The amp was still clean, and it was too loud even in that large space for me to turn it up further.
It's worth noting that Johan's headphones in his videos are the same type you'd use to protect your hearing at an indoor shooting range, except they have a cord & earpieces inside. Hearing protection is the only way he pulls off many of his videos, because a Bassman would be brutal in the size of enclosed space he's playing.
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Sounds great, but there is no stage or studio the average person has access to where they can crank a 5F6A, so to use that as an example of the tones you're going to get out of it on a daily basis is not really realistic.
It is a perfect example of what to expect from the amp. They are LOUD amps. The amps are TOO LOUD for the average bedroom player. ...
You're both right, but I agree more with TitaniumValhalla that the average player will never turn a tweed Bassman loud enough to distort, absent master volume or attenuator/reamper/load-box.
I played an acquaintance's 1958 Bassman in an airplane hangar on ~7, with a 20 or 30ft cord. The amp was still clean, and it was too loud even in that large space for me to turn it up further.
It's worth noting that Johan's headphones in his videos are the same type you'd use to protect your hearing at an indoor shooting range, except they have a cord & earpieces inside. Hearing protection is the only way he pulls off many of his videos, because a Bassman would be brutal in the size of enclosed space he's playing.
I would imagine then that it would be similar to my Hot Rod Deville, which is 60 watts without a tube rectifier. Pretty loud at 3, and at 4 it's uncomfortable to listen to. Clean channel, no master volume. However my Triple Crown is 50 watts, no rectifier tube, 4 x 12 slant cab, with independent gains for all 3 channels, as well as master volumes, and then the global volume control and that is wonderful here in my little studio.
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I understand where your coming from. For sure. I don't have any doubt with my ability to assemble the "amp" from the mechanical perspective. Where I'm at a loss is understanding how and why things work the way that they do. I don't have good understanding of how the circuit works. I can read and follow the circuit, and build as designated in the design.
Great points. If you feel comfortable doing the assembly part then you're right that it shouldn't matter whether its a champ or a bassman. Troubleshooting would be a lot different between the two, but you have some great resources here on this site and this forum that could help you out with that.
You're both right, but I agree more with TitaniumValhalla that the average player will never turn a tweed Bassman loud enough to distort, absent master volume or attenuator/reamper/load-box.
I bought a reactive load box last year and its been great for getting the cranked amp tone without making my ears bleed. Even so, you still don't get the effect of the speakers moving all that air. Just not quite the same.
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What about putting together a test-board? I find that really helpful when trying to sort out what my next project will be. There are better (safer) examples of test boards on this forum than mine, but it worked for my purposes, and probably cost me $50 in non-repurposeable parts. I've mocked up PP and SE power sections, and a few different preamps.
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On second thought, I guess the 5F6A Bassman circuit in not that complicated above a Champ in it's original form if you consider it's all amp circuit and don't have a reverb or tremolo circuits to deal with.
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You're both right, but I agree more with TitaniumValhalla that the average player will never turn a tweed Bassman loud enough to distort, absent master volume or attenuator/reamper/load-box.
I bought a reactive load box last year and its been great for getting the cranked amp tone without making my ears bleed. Even so, you still don't get the effect of the speakers moving all that air. Just not quite the same.
Thanks for posting HBP and PharmRock. So just out of curiosity, I wondered, how loud am I actually playing here in my environment? My neighbors tell me they can hear me, but not to the point of being overly annoying. Late at night 10:00 pm and later I turn it down another notch. My neighbors are pretty cool, and I've been living here a long time. So I checked the Apple App Store for a DB meter. Sure enough there are a few. I picked up one with great ratings, and installed it on my Iphone. Been doing a little checking to have some kind of reference to how "LOUD" I am playing. I figured numbers would be good, after all, things like tone and volume level and such are subjective. So with my Triple Crown thru the 4 x 12 slant cab, rated at 50 watts at the level that I normally play at I'm at a max of approx 100-105db depending on where on the neck, and my pick attack ect. 80-100 throughout most of the notes. Okay. I plugged into the Hot Rod Deville 4 x 10 ratted at 60 watts, clean channel volume on 3. max db at approx 111 and 85-110 throughout most of the notes. So the next question that came to mind was what db level was comfortable to my ears playing at and for how long? Up to 100db I can play for hours without it bothering me. Once you start going above 100 - 105db it starts to bother over any extended period of time. I think that information is useful with regards to design. One other point to mention; was, at approx the same volume level from both of the amps that I have, is that the sound from the Fender is more grating on the ear at the same db than the Triple Crown which is far more pleasant to listen to. As mentioned previously the Deville has a kind of piercing sound quality that's in general kind of annoying to my ear. I'm not sure technically what to call that, and it's not exclusive to the high register, highest frequency notes, but is more pronounced there. Maybe I could say that the Triple Crown is more "creamy" sounding, and the Hot Rod Deville is more "sharp edged" sounding. Of note is the fact that the TC has a presence control for each channel where the HRD has none. I think that also is a useful piece of information to know with regards to design. I don't like that knife edge sound, and especially when you start really cranking up the volume. It has a painful to ear type of quality to it. I want to avoid that in design. So that's a couple of points with regards to design for me to keep in mind. Now 100-110 db max is just fine for here in my little studio, but if I were to go somewhere and play with friends or something is that enough? Maybe? Enough to keep up with the drummer? Maybe not? Maybe you need 120db in that environment? So is there a way to calculate db relative to watts? The speaker cabinet that I could use is my TC 4 x 12 slant cab wired for 8 ohms for reference? Knowing that value could be very useful in gauging how much power do I need? Another consideration might be where in the operating range of the amp do you want to run? My first thought would be somewhere in the middle of the curve. Where going down in volume cleans things up a bit, hopefully without sacrificing depth, and dimension, and all the things we want, and being able to go up a bit where we start to get some overdrive out of the amp. (from the pre-amp, or power-amp, or maybe both) Knowing that formula for calculating db relative to watts at a given impedance would be good information to have when considering a design. Well I was just doing a little thinking out loud and my fingers were on the keyboard. So.......
G.
Oh one last things that may be helpful to others, Also on the app store I found a sweet little tone generator that does all kinds of neat stuff that I think you could use when building an amp for testing purposes. I used a little adapter and plugged it into my Crown power amp and played around with it 60hz, 440hz and on and on. Found out that my upper limit for hearing is about 14,000 hz. Interesting. The apps name is dB meter for anyone interested. Apple app store. I don't know if they have a version for android.
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What about putting together a test-board? I find that really helpful when trying to sort out what my next project will be. There are better (safer) examples of test boards on this forum than mine, but it worked for my purposes, and probably cost me $50 in non-repurposeable parts. I've mocked up PP and SE power sections, and a few different preamps.
An exceptionally good thought. And thanks so much for sharing. To be honest, I had a very similar though in my head in the past. I never did search for it here on the forum. But in trying to figure out a design that works for you, and in the ability to tweek, and modify it sure looks like a really attractive idea. I remember those bus connectors from being a kid at my dad's shop. He had lot's of them. Is that what their called? The black mounting boards with the screws? I can't remember the correct name.
G.
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On second thought, I guess the 5F6A Bassman circuit in not that complicated above a Champ in it's original form if you consider it's all amp circuit and don't have a reverb or tremolo circuits to deal with.
Well for me at least. Not too difficult to layout and assemble, way more difficult to understand! :icon_biggrin: I'm working on it. Currently reading "Basic Theory and Application of Electron Tubes" Dept of the Army and Air force 1952. Good stuff, not to incredibly hard to understand.
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“It has a kind of a piercing type quality to the clean channel that's hard to listen to for long. It's not very 3d sounding even with some reverb turned on”
Oh yes, they all suck now, lol.
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“It has a kind of a piercing type quality to the clean channel that's hard to listen to for long. It's not very 3d sounding even with some reverb turned on”
Oh yes, they all suck now, lol.
Hey VT!!!!! I'm not quite sure what your getting at? Are you saying all the newer Fender amps suck? or I'm not sure what you mean.
G.
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Sup G’rees
Yes I’m saying they all sound as you described. I’m incredibly picky though.
To my ears, all the new fenders are harsh , ear piercing, lacking warmth, lacking depth, they are just terrible.
I personally think this is because they just don’t make anything like they used to. Every single step in the chain adds to the character of the amp.
The resistors, the capacitors, the potentiometers, the tubes, the transformers, the speakers, the voltage, everything.
It’s just not anything like it once was.
I try to use stuff from the old days as much as possible. I got the tubes, transformers and resistors covered, and some/not all, of the caps.
I do like what Jupiter condenser company is doing. Their copper foil paper in oil caps seem to sound good.
But at $38 a piece, they may be a waste of capital if you can get some older caps that aren’t leaky for $5 each.
I’m currently in the process of building my first 100% vintage nos parts amp. I’ll be running it against the last amp I built.
I’m even going to reform nos electrolytics and use those if it works out.
To me , it’s worth it to embark on this endeavor. I’ll never know until I try.
This next build is really going to be interesting. I was at jam night at Jerry’s Bait shop in Kansas City last night, where all the groovy cats go play. A few friends of mine, and a couple of guitarists I met last night are going to be my control ears for this build. We will all be comparing the last build with this next build and some modern fenders they own.
Should be interesting. A new deluxe reverb, a 65 Twin reissue, and the two vibroverbs I’ll have.
As the one who is the builder, I think it’s best to let the people judge for me, to rule out my own opinion, take a back seat, let the people decide where the tone is.
If the 65 reissue twin wins the competition, I’ll have a TON of parts to sell, lol
I seriously doubt it though. The amount of effort and care taken into parts selection is unrivaled.
I know of no one that going about it this way.
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Not what you (or me) want to hear, but listening at 100dB for even short periods -- 15-20 min IIRC -- can result in hearing loss.
My gigging buddies are all using hearing protection of one sort or another nowadays. Not like when I was coming up . . .
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Interesting. I just performed a hearing test with this little dB meter app, and my Iphone, and a set of Iphone earbuds. Pretty cool little test actually. Analysis says I have no hearing loss, but my left ear is a little worse at 95% than the right ear at 100% . Granted it's not a real lab test, but was a little surprising really, given my age, and all the loudness I've endured over the years. Here's a little picture of the results. Cool app.
G.
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Interesting. I just performed a hearing test with this little dB meter app, and my Iphone, and a set of Iphone earbuds. Pretty cool little test actually. Analysis says I have no hearing loss, but my left ear is a little worse at 95% than the right ear at 100% . Granted it's not a real lab test, but was a little surprising really, given my age, and all the loudness I've endured over the years. Here's a little picture of the results. Cool app.
G.
That is interesting!
Doctor iPhone!! Man tech is incredible.
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Grees01
When I was building my first Champ, like you, i was reading everything I could trying to figure out how a tube amp worked.I wanted to know what was happening to your guitar signal from the time it entered the input jack all the way through the amp until it hit the speaker from the OT. To help myself I drew a graphic layout drawing that helped me study it. I was having a hard time understanding how Low voltage AC and High DC voltage was traveling in the same wire at the same time. It seemed like a train-wreck in action. Then I read how Coupling Caps(Capacitors) blocked the high voltage DC and allowed the low voltage AC that the guitar signal is riding on to pass. Har! That was a major breakthrough for me. Attached is my drawing/Graphic Layout I did way back then. Platefire
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Sup G’rees
Yes I’m saying they all sound as you described. I’m incredibly picky though.
To my ears, all the new fenders are harsh , ear piercing, lacking warmth, lacking depth, they are just terrible. I personally think this is because they just don’t make anything like they used to. Every single step in the chain adds to the character of the amp. The resistors, the capacitors, the potentiometers, the tubes, the transformers, the speakers, the voltage, everything. It’s just not anything like it once was.
Yes exactly!!!!! They just don't make em like they used to. Goes for the guitars as well. And its a crying shame. The art gets lost. In the old days the profession and the skills were handed down from generation to the next generation. Not so anymore. And everything is about cutting cost, and corners, and building faster, and more, and PROFITS.... Quality and skill takes a back seat to corporate goals. It sucks. Well I'm very happy for you that you have as much vintage materials as you do. I'm curious to know how you come to aquire it, and what about the rest of us who don't have draws full of old well made parts? Are there parts available any longer that match the quality of vintage one's? How are the F&T caps? the Sprauge Atom caps? Who makes great resistors?
G.
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Grees01
When I was building my first Champ, like you, i was reading everything I could trying to figure out how a tube amp worked.I wanted to know what was happening to your guitar signal from the time it entered the input jack all the way through the amp until it hit the speaker from the OT. To help myself I drew a graphic layout drawing that helped me study it. I was having a hard time understanding how Low voltage AC and High DC voltage was traveling in the same wire at the same time. It seemed like a train-wreck in action. Then I read how Grid Stopper Capacitors blocked the high voltage DC and allowed the low voltage AC that the guitar signal is riding on to pass. Har! That was a major breakthrough for me. Attached is my drawing/Graphic Layout I did way back then. Platefire
Man, that's a really nicely done layout PF. Thanks for sharing. Yea I've got a bit of a handle on how caps allow ac voltage to pass thru but block the DC voltage from passing. It was weird to find out that both AC/DC can co-exist on the same wire. I was like "really????"
G.
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What about putting together a test-board? I find that really helpful when trying to sort out what my next project will be. There are better (safer) examples of test boards on this forum than mine, but it worked for my purposes, and probably cost me $50 in non-repurposeable parts. I've mocked up PP and SE power sections, and a few different preamps.
An exceptionally good thought. And thanks so much for sharing. To be honest, I had a very similar though in my head in the past. I never did search for it here on the forum. But in trying to figure out a design that works for you, and in the ability to tweek, and modify it sure looks like a really attractive idea. I remember those bus connectors from being a kid at my dad's shop. He had lot's of them. Is that what their called? The black mounting boards with the screws? I can't remember the correct name.
G.
I think generally they're called "Terminal Strips" ... here's a useful link: https://el34world.com/Forum/index.php?topic=15445.0
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barrier terminal strip
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Sup G’rees
Yes I’m saying they all sound as you described. I’m incredibly picky though.
To my ears, all the new fenders are harsh , ear piercing, lacking warmth, lacking depth, they are just terrible. I personally think this is because they just don’t make anything like they used to. Every single step in the chain adds to the character of the amp. The resistors, the capacitors, the potentiometers, the tubes, the transformers, the speakers, the voltage, everything. It’s just not anything like it once was.
Yes exactly!!!!! They just don't make em like they used to. Goes for the guitars as well. And its a crying shame. The art gets lost. In the old days the profession and the skills were handed down from generation to the next generation. Not so anymore. And everything is about cutting cost, and corners, and building faster, and more, and PROFITS.... Quality and skill takes a back seat to corporate goals. It sucks. Well I'm very happy for you that you have as much vintage materials as you do. I'm curious to know how you come to aquire it, and what about the rest of us who don't have draws full of old well made parts? Are there parts available any longer that match the quality of vintage one's? How are the F&T caps? the Sprauge Atom caps? Who makes great resistors?
G.
There were two amazing spots I visited, one giant electronics surplus store in Dayton Ohio (can’t remember the name) that was in 2010.
And a few other electronics stores, one in Odessa Texas, one in midland.
I’ll never forget the day I walked into ESI supply in Odessa. I went there to pick up a few supplies for work when I noticed rows and rows of NOS Allen Bradley carbon comp resistors, then I turn the corner and there was a whole shelf with dusty triad transformer boxes sitting there.
I talked to the owner who was happy to sell me everything I wanted for cheap. I ended up paying $20 per transformer, and I think $80 for THOUSANDs of resistors. Picked up some 6 pin and 4 pin tube sockets too so I can get my #42 tube and #80 / 5Z3 groove on.
The 80 is a four pin 5y3 and the 42 is a groovy true pentode, not tetrode as the 6v6 / 6l6 are.
The #42 really is a great little bugger. I’d take it over a 6v6 any day.
I built an amp with three 6sl7 tubes in the preamp and four #42 output tubes. It may put out 22-25 watts, but the break up on that amp is the best distortion ive accomplished yet.
Anyway, eBay has some stuff if your in a pinch, some prices are reasonable, some are outrageous, and you never know what your gonna get as far as if it’s a good part or not.
But if you haven’t been scouring at estate sales/ electronics shops for a decade, and have no luck doing so these days, than ebay is about the only place I know of for old parts.
Partsconnexion in Canada and upscale audio used to have surplus parts and sometimes they will run into new lots and sell them on their site.
F&T and sprague are the standards these days for boutique builders. Ive used them both, they are reliable and effective. But there are certain values they just don’t make any more.
A 16uf 450v cap is not available that I know of (for example).
And maybe I just need to look harder, but must people just through in a 20uf at 500 and call it good. And it’s prolly fine, but I can’t help but wonder how that may effect the responsiveness of the amp.
The touch sensitivity and sag and breakup responsiveness is largely a part of power supply performance.
So when someone says that electrolytics don’t effect the sound , I kinda say that the fact that the signal doesn’t pass through those caps, is really only part of the story.
Let’s say it effects the feel of the amp. Hows that.
Now I’m not saying you should use old electrolytics, unless you want to reform them, but I am saying that just like everything else, it’s not what it once was. Still good, just different.
What we can be greatfull for, is that there are companies out there trying to revive the lost art.
Western Electric for example, is making 300b tubes here in America again , with the old tooling, and they have made a huge effort to get it right.
Jupiter condenser co, is making groovy speakers and capacitors.
Weber has been at the tip of the spear, magnetic components inc, was and unfortunately not now, making transformers to vintage spec, as with mercury (which I don’t recommend) and a host of others.
So while the old recipes seem to hold the best tones, at least we have options for new parts, because some day, the last filament will burn out on an old telefunken ecc83, the last nos thordarson transformer will be thrown in the trash, etc, etc.
These companies are keeping tube amps alive by making modern equivalents , and that’s pretty groovy, even if it’s not perfect.
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Grees01
I’ve read through this whole thread and it just ends. What did you end up building?
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Grees01
I’ve read through this whole thread and it just ends. What did you end up building?
It looks like Grees01 hasn't been on the forum since June 2022.
You might be better served by sending him a PM since that should go to his email, in case he's not looking at this forum anymore.
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Thanks.