if we assume
I get thatDo ya?
... PRS Mark Tremonti MT15 was born. ... How the heck did they do this and keep the 6L6 in an operational range where it still sounds even half way decent at that wattage? ...
If you want to run push-pull 6L6 at 15w output power, the answer is right on page 2 of RCA's 1934 data sheet (https://frank.pocnet.net/sheets/021/6/6L6.pdf). Just run them at 250v plate & screen with a load of ~5kΩ.Then you're biasing to like 70mA.
If you want to run push-pull 6L6 at 15w output power, the answer is right on page 2 of RCA's 1934 data sheet (https://frank.pocnet.net/sheets/021/6/6L6.pdf). Just run them at 250v plate & screen with a load of ~5kΩ.Then you're biasing to like 70mA.
Not arguing with the merits of this approach to low-wattage 6L6GC, but in this case (The PRS MT-15) we know the tubes are biased to 30mA +/- mA. ...
I’ve heard several reviews state all 5 tubes are used on the gain channel.
Jim
I’ve heard several reviews state all 5 tubes are used on the gain channel.10 triodes?
It sure does a lot of things well.of course the amp does, the more knobs the better; when you can't play you need something that makes you sound good :icon_biggrin:
Well the reason I’d like to know how PRS did it is it sounds pretty darn good. ...
forgive my FX loop - never designed one - that's my take on where to start
10 triodes?
Well this is interesting
I've never seen an amp that has 1 knob for each triode, and bonus, you get 2 switches for free :icon_biggrin:
"i would love to see this amp come to life with a real guitar player who's playing a proper telecaster."
Ok, this is the most inflammatory thing that has been said or inferred on this thread... Gosh Pete, Silvergun and I are friends - and I thought you were my friend as well. I guess I need to re-evaluate that now. Geez, way to throw a wet blanket on a serious topic.
I will try to look past this grave offense to myself and my friend Silvergun until I decide on our friendship and keep the subject on track.
I know this is your interpretation of what you are seeing. Do you really think the power switch is for triode/pentode operation?
Jim
Quoteforgive my FX loop - never designed one - that's my take on where to start
Pete, I really like that FX loop and I think it's well thought out! My experimenting around with FX loops (to get them sounding like I want) and modifying them sort of has my thinking heading that direction. Good job!
I really appreciate your insight into amp building and all the great innovative designs that you share! :thumbsup:
Your contribution to the forum is generous and remarkable! Thanks! I find myself saving the majority of the designs you post.
With respect, Tubenit
In the video link i posted, guy was saying that te 120R/25W resistor was connected to the half power switch, so i still think its for lowering voltage. But on the other hand usually that type of switch is pentode triode switch so who knows.I was staring at some pics I snagged off of the video and... :dontknow:
Who cares exactly how PRS did it? If the basic question is, "How can 6L6GC deliver only 15w," then the data sheet shows how. ...
Well this is interesting. A very long video with the result being ~25 watts ...
:laugh: Again... we're down to whether the point is debating the PRS amp, or building a 10-15 watt amp with "big power tubes." The latter is not that hard.
:laugh: Again... we're down to whether the point is debating the PRS amp, or building a 10-15 watt amp with "big power tubes." The latter is not that hard.
If we go down the latter path, the difficulty (for a DIY builder) seems to be finding a suitable power transformer.
Most available transformers with heater current enough for big bottle tubes and a few preamp tubes are big and with high anode voltage.
...
How would you approach this?
In addition, you probably want a separate and higher anode voltage for the preamp. This may require a separate HV winding.
... In addition, you probably want a separate and higher anode voltage for the preamp. ...
When you lower the supply voltage to the output tubes, the bias voltage needed goes down. ... With 1/3 the output requirement, high preamp supply voltage is not needed for drive signal to the output tubes. ...
The other thing to remember is this is actually (if true) a 25/12 watt ampAt about 8:00 he pauses and observes 6.8% THD, if you do the math at that point you get 13W. At 7.8% he sees first signs of clipping and settles on 25W.
The other thing to remember is this is actually (if true) a 25/12 watt ampAt about 8:00 he pauses and observes 6.8% THD, if you do the math at that point you get 13W. At 7.8% he sees first signs of clipping and settles on 25W.
If we measured max clean output power using a THD meter only, I'm not sure we'd allow more than say 5% THD for our rating? Just an example that comes to mind, the Fender Blues Deluxe/Deville schematic calls for output test at 5% THD.
Anyhow, I think this goes to show how much we can fudge an output test one way or the other to please the marketing dept.
But I was wondering in contrast to HPB's assertions regarding lower voltage design, what about running 6L6's in a Deluxe circuit (using like the Allen TP40D PT for proper rating), they say it's still around 25W-ish running the 6L6's. How does this solution compare to the lower voltage design?
The other thing to remember is this is actually (if true) a 25/12 watt ampAt about 8:00 he pauses and observes 6.8% THD, if you do the math at that point you get 13W. At 7.8% he sees first signs of clipping and settles on 25W.
If we measured max clean output power using a THD meter only, I'm not sure we'd allow more than say 5% THD for our rating? Just an example that comes to mind, the Fender Blues Deluxe/Deville schematic calls for output test at 5% THD.
Anyhow, I think this goes to show how much we can fudge an output test one way or the other to please the marketing dept.
But I was wondering in contrast to HPB's assertions regarding lower voltage design, what about running 6L6's in a Deluxe circuit (using like the Allen TP40D PT for proper rating), they say it's still around 25W-ish running the 6L6's. How does this solution compare to the lower voltage design?
Yes, the PRS preamp is a hi-gain distortion machine. W/o a THD meter how would anyone know if the power tubes are distorting beyond the "max standard" 5% or not? :laugh:
Well the reason I’d like to know how PRS did it is it sounds pretty darn good. We know the transformer specs and it looks like a full wave rect so you figure ~425 on the plates. I also like how it’s voiced. Pete’s layout shows a 2204 two tube style pre. I’ve heard several reviews state all 5 tubes are used on the gain channel. Still lots of questions - at least for me. My original question pertained more to overall performance as well as how the heck do they get 7 watts out of this thing. Just not used to big tubes being used this way.The just hid the components of you linear boost in the signal path. That is how. And KT88's sound NOTHING like this amp. I believe this is simply preamp gain as it sounds a lot like the Fuchs Overdrive Dumble SS reverb thingy that comes with 5881's. Friend has one and blew the PT it it and I had one 275-0-275 that had the needed ma and used it.
Jim
STILL no reverb & no tremelo. bah! u don need no stinking reverb & tremelo señor!:sad2: Bah is right! :laugh: But now Jimbob isn’t going to have any help covering up all of his misfrets and wrong notes? :dontknow:
STILL no reverb & no tremelo. bah! u don need no stinking reverb & tremelo señor!:sad2: Bah is right! :laugh: But now Jimbob isn’t going to have any help covering up all of his misfrets and wrong notes? :dontknow:
You are the schematic king Pete! I only would like a bi-color single LED on my model please? :icon_biggrin:
plus another threadya, n tell me how that thread started with 33 reply's n 22 views :icon_biggrin:
I don't think I've ever heard a KT88 slammed in true triode mode.:laugh:
QuoteI don't think I've ever heard a KT88 slammed in true triode mode.:laugh:
I can hear the audiophile types cringing across the world :icon_biggrin:
Uh err NO! Porn doesn't count. Those are fantasies kimosabee Turtle! And SG asked to be left out of them!
Well, SG, thanks to the people who actually CONTRIBUTED, I do have some ahhdeas…[/l]
Bah! NO! Anyone with experience knows that cascading even a couple tubes can bring about parasitic oscillations and other hypersonic animals buzzing around one's head driving it's unwitting creators batty enough to eat snakes from the bush meat market!
If I were to build this...… And guess what? I am seriously thinking about doing just that. Now where did I put my soldering iron.... :think1:NOBODY would want to try to help you troubleshoot this nightmare.
Once I considered posting a photo of just my =C=, not even any GEC's. Then I remembered Silvergun built 2 amps that needs one each. One is not THAT expensive unless you want real ones and he seems to want real ones. So I decided not to poot them so he couldn't download the photo. Look closely at the glass to find a familiar reflection. Search the image with google search and drive from yankee town and borrow some.QuoteI don't think I've ever heard a KT88 slammed in true triode mode.:laugh:
I can hear the audiophile types cringing across the world :icon_biggrin:
oh, no worries sniffer types, we won't use NOS KT88 in a guitar amp... no sir, no way.
i lie like a cheap rug. :icon_biggrin:
--pete
y'all are gonna get us upgraded to the bitchersons.Damn, we are trying. Where is PRR?
jimbob - baby steps. build the champ first. :icon_biggrin:
--pete
jimbob - baby steps. build the champ first. :icon_biggrin:agreed!, I even build one with a KT88!!
Pete,
THANKS for your contributions to the forum and on this thread! IF you still have the SCH version of this proposed Jim-Bob Special with 6L6's and KT88's, can you post them on this thread OR in the ExpressSCH Library, please? If you post them on this thread, I'll move them over and be sure to note that it's your work.
http://el34world.com/Forum/index.php?board=12.0 (http://el34world.com/Forum/index.php?board=12.0)
Even if Jim doesn't build this amp, there may be someone down the line interested enough to pursue it.
Thanks, Tubenit
con·trap·tion
/kənˈtrapSH(ə)n/
noun
a machine or device that appears strange or unnecessarily complicated, and often badly made or unsafe.
Ok, I’ll participate,
Because I appreciate Mid-west reality in a field of costal weeblees I will meet you ½ way with my last build. should be a cornfield in IL :laugh:
The pre can produce a square wave at ~70Vacrms, (with HOT guitar). the bias is set to sweat the 88 at ~41W so don’t roll in any family heirlooms without tweaking Rk :icon_biggrin:
It even has some stole ideas from Marshall, DCCF and a sucky TS (CCW 9 3 CW)
Put a switch on G2 and hear triode mode, cut your boat anchor pre-out into the 88’s coupler and you have a 18W screamer WITH a triode switch
And use your stack (amp is 4/8ohm switchable)
There!
Batter up :icon_biggrin:
that thing has more than 2 tubes:icon_biggrin:
but I like Monster Trucks too.what, with a 2.5L eco-boost :icon_biggrin:
Well Pete, I just looked closely at the Job-Bob Shredder. Very tempting, that is all I have to say. That is a lot of tubes to make 25 watts, but I like Monster Trucks too. Very nice, but JoJo has a valid point. Better be on point with a layout.
do you think jimI'm holding out hope for the weather to break, then Jim can grab his banjo n go sit by the big river. :m17
I know he wouldn't EVER admit to having one. How could he? I called it the Job-Bob, typo. The Jim-Bob Sherdder for those who shredded their diapers when baby and have reached the age to begun doing it again!Well Pete, I just looked closely at the Job-Bob Shredder. Very tempting, that is all I have to say. That is a lot of tubes to make 25 watts, but I like Monster Trucks too. Very nice, but JoJo has a valid point. Better be on point with a layout.
thanks! - it's the JIMBOB shredder. we need to show jim some respect. JOEBOB is just too...southern?
do you think jim will ever come to the light side and buy a tele?
--pete
some edits. LED polarity fix, added boost to clean channel, footswitch/front-panel channel switching, etc..
STILL no reverb & no tremelo. bah! u don need no stinking reverb & tremelo señor!
--pete
I know he wouldn't EVER admit to having one. How could he? I called it the Job-Bob, typo. The Jim-Bob Sherdder for those who shredded their diapers when baby and have reached the age to begun doing it again!Well Pete, I just looked closely at the Job-Bob Shredder. Very tempting, that is all I have to say. That is a lot of tubes to make 25 watts, but I like Monster Trucks too. Very nice, but JoJo has a valid point. Better be on point with a layout.
thanks! - it's the JIMBOB shredder. we need to show jim some respect. JOEBOB is just too...southern?
do you think jim will ever come to the light side and buy a tele?
--pete
I am not sure how Jimbob got so against Telecasters and John 5, but he also thinks the Japanese made a Deep Purple record, the 3rd largest live album of all time. Made in Japan.
Wasn't the big hit from that album called "I Want You to Want Me?", or is that just a better song I remember from some other Japanese Vinyl?
Bias Jacks and Pot: These jacks measure the power tube current draw in milliVolts.
1mV=1mA.
As an aside, it's interesting this amp has no choke but you do find a 120R 25W between standby and OT CT. Weird or just me?
This is the design element I wasn't thinking of. With a resistor in place of a choke but placed before the first filter node it will act as a full wave-choke input rectifier design.I don't think so?
This means that you take the secondary voltage and multiply it .45
Awwwww crap :BangHead:This is the design element I wasn't thinking of. With a resistor in place of a choke but placed before the first filter node it will act as a full wave-choke input rectifier design.I don't think so?
This means that you take the secondary voltage and multiply it .45