Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Papa Jim on April 05, 2019, 09:50:41 am
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Someone gave me PT, OT, and Choke out of a Fender DRRI amp so I think I am going to build one of these. I have a lot of the other parts on hand also. I want to make sure before starting that the schematic and layout on this link is the latest, or if there is any other info that would be beneficial before starting this build. I'm pretty sure it would be but just double checking for my own sanity. http://sluckeyamps.com/misc/AB763_Deluxe_Lite.pdf
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Doe's a parts list exist. If not I'm assuming all the carbon comp's are 1/4 W and the Films are 1W ?
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All resistors are 1/2 watt unless specified on the schematic. I recommend metal film for all 1/2 watters and 3 watt metal oxide for all others. It's a small parts count so make your own parts list. That's a good way to get familiar with the amp. I'm not aware of any problems with these drawings. There are several discussions about this amp. Search for "deluxe lite" on this forum.
I NEVER BUILT THIS AMP! Several others have.
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Very cool, I bet this turns out great! You may already be aware but Rob Robinette has a very similar amp concept with schematics and lots of data on his website as well. He also has a wealth of information on classic AB763 circuits in general, definitely worth a read through if haven't done already. https://robrobinette.com/RR763_BLACKVIBE.htm
Good luck and let us know how it goes!
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I built the amp, plays fantastic as drawn, sounds great, no problems.
One of my favorite amps.
Only change I made was to lower cathode caps to 4.7uf and 10uf, preamp, most Fenders IMO, are a little too bassy with 25uf's.
al
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Thanks to all. I will keep ya all posted.
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I've also built this amp. It's a cool build! I reduced power to the preamp a bit for more gain and installed a master volume. The master volume really isn't that helpful in this amp... but I put it in place of the voltage divider before the PI. Have fun!
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Why are there 2 different build options for the PS Filter cap board? One has a note that it is for a deluxe reverb so I assume the other simulates a plain deluxe model. This amp has no reverb though so which to use and is there a tone difference. Doe's it matter which one I select?
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The one on top is for the Deluxe AB763 6V6 based amp ***ONLY***. The one on bottom is for all the 6L6 based AB763 amps. They are different. Look at some AB763 schematics.
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Ok. Perfect I will be using 6V6's and I have a 40/20/20/20 can cap I wanted to use. Thanks.
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That can will make for a nice neat and compact power supply. All the resistors could mount directly to the can.
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Sure does! Excellent idea. Thanks.
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Can't seem to find a color code anywhere.
I think the red's are B+ with red/yellow the C.T.
red/blue 38vac
green's are filament.
yellow's 5vac
possibly{ red (hot) white(neutral) }
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Find a schematic for a Fender DRRI, see what colors they show.
Then test those colors/pairs for continuity/resistance, to each other and not to any other wires.
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ah ha. Got it. I would have sworn the colors weren't on the schematic but they were. Geez what a beginner :laugh:
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Everything is cool. :icon_biggrin:
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Do you think my tone would suffer any if I used SS Rectifier with Sag resistor possibly or not? I've never had a tube rectifier to compare tone.
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Just build it with a socket wired for a 5Y3, or 5AR4. Then also buy a plug-in SS rectifier (with or without sag resistor) from Weber. Now you can have both and you will be the expert that can answer that question next week when it pops up again. :icon_biggrin:
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Never knew of such a SS rectifier that fits a tube socket. I will have to add a 5y3 to that list also in order to compare. :icon_biggrin:
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Due to pre-existing holes in this chassis I am re-purposing before I drill screw holes I would like to do it like this but. Is this orientation ok, or is there any other locations that would be better. I can rotate any of them if need be.
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That's about how I placed them for my last build. I had no problems. Maybe slightly further apart.
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You may want to make a cardboard template to represent your circuit board. Might help figure out positions so nothing interferes with anything else.
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Clearance's will be fine Sluckey, but actually my choke orientation would be ideal if this is ok. I know they say 90 degrees though but I am not sure exactly how they determine that or if that applies to the choke too. Is this pic ok with the choke like this? Any way I rotate it in the same plane seems like would be ok in relation to, since the laminates are vertical and not horizontal like the PT.
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Probably fine. Let's see the whole chassis.
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Here some pics. The intent is for a re-purpose of chassis and most parts build because I am cheap. :l2: All the extra chassis holes will be plugged with steel pop in plugs, and faceplate made to cover the extra pot holes. Only gotta get a one more 6v6 and it's socket so the bang for my buck will be extremely high for this amp build. Gonna save a lot of space doing the filter cap with the resistors soldered right on it's terminals like you suggested Sluckey. Also just going with 2 diodes in the ps instead of tube for now.
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Also just going with 2 diodes in the ps instead of tube for now.
I highly recommend using four diodes, two on each side.
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Your talkin 4 total but not a 4 diode bridge because I have a center tap aren't you?
If so series for some reason or parallel for if one blows? Or something else.
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like this;
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ok gotcha shooter and just read valve wizard why. Thanks guys
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Hey Sluckey gonna get a start on this baby tomorrow with the parts I had on hand. Ordered the remainder of parts today. :icon_biggrin:
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Any progress? Forward or backward?
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A little bit. Got the trannies and sockets mounted. Some things came up to delay me, but just this week back to normal and wife will be gone all next week. Lot's of time to get a handle on it. I feel like tomorrow I will get back to it on a steady basis Sluckey. Got my parts all gathered up also. Gotta take some progress pics also.
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Progress today. Ready to load up the turret board.
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Off and running on the turret bd. that I re-purposed by removing all the turrets and filling the old holes with epoxy and sanding smooth. Also has turrets removed from a different build. Ignore the 5 watt - 1500R cathode resistor. I couldn't come up with one smaller in my spares. It's all good though. Not going for beauty but functionality and tone only. :icon_biggrin:
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I found one. Doe's this look better sized for R5 guy's. :icon_biggrin:
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Got some more done.
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There's gonna be lots of sensitive signal wires crossing over/around that cap can. The first cap in that can will have lots of strong 120Hz ripple (maybe even up to 10V). Could be a noisy/hummy problem. I would have put that cap can down in the power supply area, maybe even mounting it on the side wall over the PT.
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I can do that. The layout from the ax84 4-4-0 that this chassis once was used for had it there for some strange reason.
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Slucky either 1,2,3 or 4 I can make work it. Even the outside of chassis if I choose to keep the whole length out I have enough room in the cabinet it is going in. Are these good places to start with.
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Slucky either 1,2,3 or 4 I can make work it. Even the outside of chassis if I choose to keep the whole length out I have enough room in the cabinet it is going in. Are these good places to start with.
I prefer 7. :icon_biggrin:
It's OK to mount these cans inside the chassis if desired. Don't have to carve a big hole.
I looked at that 4-4-0 amp. It's a very small amp. They usually don't make as much B+ noise as a real amp. Even so, I don't think the ax84 crew put much thought into the location of that can.
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Ok cool. Gonna do it inside on the back wall beside the ac inlet probably.
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You'll be happy with Sluckey's Deluxe lite, I'd put in a M/V, I think his layout or schematic shows one. Helps to get a little more distortion at a lower volume, I used a pre-PI master, that's what Sluckey's schematic shows, if I remember correctly.
al
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You'll be happy with Sluckey's Deluxe lite, I'd put in a M/V, I think his layout or schematic shows one. Helps to get a little more distortion at a lower volume, I used a pre-PI master, that's what Sluckey's schematic shows, if I remember correctly.
al
not one on the layout or schematic. Gonna build it as is first to hear it then if I want I have a london power mv I can always add later. Gotta hear it stock before I mod it so I know if any mods mess it up. I doubt if I need one because I mostly play fairly clean. That's why I chose this one. :icon_biggrin:
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I built mine with a SR power supply and cap setup, used a single 100 watt Celestion 12", and never looked back. This amp LOVES pedals, I added a variable negative feedbck which adds a nice low end bump at lower volumes...really nice in a small stage footprint.....
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I plan on using a I believe is a 35w 12" Celestion Greenback because it is already in the cabinet this amp is going in. Hoping that it works out.
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Added some labels, cap can, virtual ground, and filament wiring to the schematic for my own use. Can you all take a look at it for mistakes before I start wiring it.
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Added some labels, cap can, virtual ground, and filament wiring to the schematic for my own use. Can you all take a look at it for mistakes before I start wiring it.
Sure. Bring it over this afternoon anytime after 5. Pick up a 12 pack of Ice House. Stop in Atlanta and pick up Ed too. He's a hoot! :icon_biggrin:
Or you could just post some pics!
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Whoops. My head is in my......well you know where. :l2:
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Did you purposely omit one of the bias caps?
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Yep. You gotta problem with that. :l2: :l2: :l2: The can only has 4 caps in it. jj 40/20/20/20
Or are you talking about my crazy nomenclature of C12/C13 for a single cap. :laugh:
I really think there's 5 20uF. caps inside that thang. :l2:
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Did you purposely omit one of the bias caps?
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Did you purposely omit one of the bias caps?
Did you not see post #49
Ya see that light. I got filaments. :icon_biggrin:
I do know what I'm doin.....I did get a light!!!!!
I do know what I'm doin.....Well maybe!!!!!!
I do know what I'm doin.....NOT!!!!!
:l2: :l2: :l2: :l2: :l2: :l2:
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Did you purposely omit one of the bias caps?
Did you not see post #49
Yes I did. It has nothing to do with my question so I repeated the question because you did not read it correctly. You asked to look over your schematic and I did. I saw the missing cap and asked the question. Now once more...
Did you purposely omit one of the bias caps?
Just messing with you. I see you do have two bias caps on the board. :icon_biggrin:
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Duuhh. Have I ever said the board was done. Besides Bias and PT are kinda the same thing.....Are they not?... :l2: :l2: :l2: :l2: :l2: :l2: :l2:
Is this better. C17 added to the schematic to match what has been on the board for several days now.. :l2: :l2: :l2: :l2: :l2: :l2:
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Now was that so hard? :icon_biggrin:
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Not too bad. :icon_biggrin:
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Don't know if you have noticed but a real Fender AB763 only has one bias cap. They started using two caps later when they switched to that funky bias balance pot that had a center tap in addition to the normal three lugs.
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Did not notice that. I read about that funky pot not long ago. Glad this design doesn't have one.
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Is there room for another cap at the top of R35? Two RC stages of filter for the bias supply is a good idea.
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déjà vu :l2:
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There's plenty of room but I really want to build it as is first before doing any mods.
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Thanks but I'm sure if it needed that Sluckey would have added it. IMHO
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Thanks but I'm sure if it needed that Sluckey would have added it. IMHO
He did! it's C17. That's why I gently brought it up. Sluckey's efforts to tell you didn't seem to work.
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Sorry Tony Bones. I thought you were talking about something different because I had added C17 back in post #53. Now it makes sense why Sluckey said deja vu. :l2:
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Sorry I missed where you added it. :icon_biggrin:
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we're even. I missed what you were saying. :laugh:
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To be honest, I got to the bottom of the first page and thought that it was the end of the thread. I didn't even see the entire second page where Sluckey invested so much effort explaining about the second cap, never mind where you added it. Sorry I'm such a dope sometimes... :laugh:
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Filament artificial ground 100R's connect to gnd buss at Amps input jack end or the output end of the buss? Using a single point with buss connected to chassis at the input jack.
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the output end of the buss
If the tranny had a CT, I believe it's typical to ground at the dirty end. You don't want a 3VAC signal too close to a 20mVAC input
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Ok. The PT. Center tap, Filament artificial gnd and the common gnd from all the B+ caps are all close together. I am thinking about connecting them all together at my can caps common terminal and taking one wire to the dirty end of the buss. Here's my changes to the schematic that reflect that.
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I would not put all that dirty stuff on the ground bus that runs behind the pots. I would connect all the dirty to a PT bolt or a dedicated ground lug near the PT. My pot bus is only connected to chassis using a dedicated ground lug near the input jack.
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Filament voltages.....Check.
Unloaded B+ Voltages......Check. They are all close to 440 vdc.
Bias voltages tomorrow.....and get started from the input jack onward.... :icon_biggrin:
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I would not put all that dirty stuff on the ground bus that runs behind the pots. I would connect all the dirty to a PT bolt or a dedicated ground lug near the PT. My pot bus is only connected to chassis using a dedicated ground lug near the input jack.
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Ok. done.
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Guess I shoulda looked at your layout Sluckey. :BangHead:
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Close but no cigar.........yet!
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So with current limiter did all the voltage pre-checks.
All were as expected.
Turned the bias pot for the most negative voltage.
Put preamp tube in looked good with No Redplating.
Put PI tube in (5751) forgot to order 12AT7. Looked good with No Redplating.
Put both 6V6 output tubes in. No Redplating.
Removed current limiter.
Checked cathode current with Plate to Cathode voltage measuring 439 vdc.
V3 has 20ma.
V4 has 15ma.
For bias pot I didn't have a 10K so I had to put a 25k pot in.
Should I tweak on the plate resistors to get them both at 15ma. which will give me some adjustability for added current with the bias pot.
Oh be the way I strummed the guitar briefly and it amplifies and so far seems really hum quiet.
Pics of the amp and cab. Pic of my mancave closet workshop. Lol
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Should I tweak on the plate resistors to get them both at 15ma
If you're talking about the PA tubes, they have no plate R
the math says 439 * .02 = 8.8W which is a good place for fixed bias 6V6(?)
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I'd say you have arrived! That imbalance between the output tubes is due to the tubes. I would just live with it. But you can spend some dollars and roll a bunch of tubes through the amp until you get a perfectly matched set. And two months from now they probably won't still be a perfect match. Let your ears tell you what you think. BTW, there ain't no plate resistors to tweak on to match the tubes. Those tubes are connected to a transformer. :icon_biggrin:
You know, when I say I'm working in a tight space it usually means I'm in a tweed style chassis. I can see that tight space has a totally different meaning for you! :l2:
I know the feeling. I've been there before.
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Yeah, but I wanted plate resistors. Lol. Ok cool, I will just live with it. According to the numbers I punched into some online bias calculators I think I am running at 70% dissapation.
I'm gonna play it for now and see what I think. Thanks guy's for all the help. :worthy1: It's been quite a lot of fun ribbing each other. :l2:
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You know, when I say I'm working in a tight space it usually means I'm in a tweed style chassis. I can see that tight space has a totally different meaning for you! :l2:
:laugh: Actually I have it made. I have one side of a 2 car garage loaded with my tools and a workbench but I prefer to work inside. I'm too nosey what's goin on. :l2:
Have been able to play the amp about 10 minutes and Oh My Gosh. It is awesome. I got it going to a Celestion G12M greenback. Now I know what a real amp is supposed to sound like. I've been jacking around with crap for years. Can't wait to get some more time with it. :icon_biggrin:
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I built in 2019 but it is hard to use anything past 1 on the volume pot. That can't be right. What should I look at?
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I built in 2019 but it is hard to use anything past 1 on the volume pot. That can't be right. What should I look at?
What is your exact schematic?
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https://sluckeyamps.com/misc/AB763_Deluxe_Lite.pdf
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First thought, linear pot vs log on your 1M volume?
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Also this https://el34world.com/Forum/index.php?topic=21776.0
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First thought, linear pot vs log on your 1M volume?
+1
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My bad. I had dug this amp out of the closet from where it had set for a long time and forgot I had already added a MV years ago. You jogged my memory and all is good now. It sounds great. Getting some twang
thanks.