amplifiers with 3 power tubes

[sunn drone]

I think i've seen and almost remember seeing some oddball amps with 3 power tubes . Is there such a thing? I remember looking at a 2000s sunn and it has 2 rectifiers . Would an amp with 3 power tubes need 2 rectifiers? Could you then mix the power tubes, say 2 6l6 and a 6550 . I seen on you tube they mix power tubes with the newer randall 100 watters. I'm into the tweed sound and wonder if It might be something that could give me the 6l6/ 6550 sound.

[Justin Thomas]

Except in very rare cases, power tubes are used in pairs. The main exception being in parallel single-ended, and you could wire up as many tubes as desired to get the output you needed. There are many amps that use a "power" tube for some other purpose - some high-power Fenders used a 6V6 as a driver for PI transformer, and the VibroKing used one or an EL84 to drive the built-in reverb. I'm sure there are others. They may seem like there's an odd number of power tubes, but tubes can be used for more than one purpose...

Two rectifiers were used in the Sunn because one alone couldn't satisfy thd current requirements. I'm sure uf you used 3 EL84s in ll SE it could use one rectifier. But that hss more to do with the size and type of tubes used, not how many. Check yhe tweed Twin schems for an amp from the 50s w. 2 rectifiers.

I'm not knowledgable enoigh to say how Randall mixes power tubes; can you post a link to the video? Mesa's been doing it for quite some time, too. But I doubt they use odd numbers of tubes. I'm sure it could be done, if you're patient and daring. And SOMEONE here knows how to do it...

Justin

[loudthud]

There were one or two amps from the 60s that had three power tubes. They used one as a Voltage regulator for the screen grids. A single ended amp could use three power tubes but output power would only be 10 to 20 Watts per tube. A push pull amp could be built with two tubes on one side and a larger one on the other,,,,, I wonder why Mesa hasn't done that yet haha.

[Leo_Gnardo]

There was a 50's Gibson 2-tone Les Paul GA40 IIRC that used 2x6V6 for power and another 6V6 for tremolo. First time someone brought one in for repair I was bemused to see 3 power tubes but once I figured only 2 were in the power circuit I settled down some.

There's some amp "genius" a couple towns away in Beacon NY who makes a 3x6V6 amp, so he claims. Never saw one in person and so far no rock stars have made him rich & famous, it's a big "so what" far as I'm concerned. Same guy was flogging his '63 brown 2x10 Vibrolux for $10,000 on Craigslist a couple years ago. I got advice for him: don't quit your day job.

Mixing output tube types done by Mesa with 6L6 and EL34 but they quit that, thank hevvins. Now Egnater has some amps that allow you to select and blend different output tubes. I've worked on a couple of them. Don't hear any sonic advantage to either the Egbeaters nor the Mess-a-boogers. Just an exercise in unnecessary complexity. Eg's use a 4-deck pot to do the blending. Good luck finding 4-deck pots for home experimenting. If Randall's doing it too, must be they're bored and drinking way too much coffee in the engineering department. All in all, file under "why bother?"

Stick with the tried & true formulas if you want that "tweed sound." You'll do way better experimenting with tone stacks & speaker choices than mix n match power tubes. AFAIK nobody produced a successful amp with mongrel mixes of output tubes in the days of tweed. Heck I don't think anybody even tried it, would have been considered heresy. Properly so.

[sunn drone]

3 power tubes

randall satan power tube test right at the end of the you tube mixes 6l6 and kt88. You could do a mix with 50 watter since it has adjustible bias for each tube but thats only 2 tubes. With a 6550 I'd worry bout screwin up a nice amp. And then again It wouldn't quite be a tweed thing runnin randall. They have phase inverter and not a rectifier like tweed amps do ta get get the sag,or lag......

[sunn drone]

3 power tubes

AmpMonster Tube Amplifier Repair: 1957 Fender Tweed Twin Restoration Project this is interesting.
Fender Schematics - Tube amp Schematics thanks thus far.....

[mikeydee77]

Does three ECC83 count? Those little sheldon 1 watt amps use three ECC83, so six triodes in their one watt amp's output stage. Sounds great too.

[Mick Bailey]

As an expansion on this thread, the Laney LH50 uses 5xEL34.

[PeanutNore]

If you biased them correctly, I don't see any reason why, in a push pull amp, 2x 6V6 on one side and 1x 6L6 on the other wouldn't work. No guarantee that it would sound any good, though. Just saying, it would probably work.

[Chuck H]

AmpMonster Tube Amplifier Repair: 1957 Fender Tweed Twin Restoration Project this is interesting.
Fender Schematics - Tube amp Schematics thanks thus far.....

Is this post just to share an interesting link or are you trying to show us an amp with three power tubes? I'm confused (but entertained).

[Shane]

Does three ECC83 count? Those little sheldon 1 watt amps use three ECC83, so six triodes in their one watt amp's output stage. Sounds great too.

Actually the output valves on those are ECC82 as designed, though its possible to use ECC81 and 12BH7.
ECC83 were never recommended. And yes they do sound good!
But then I'm biased 'cos I designed 'em and built most of them

Cheers
Shane

[Jammin'John]

3 Power Tubes

I have one.

JJ

[Chuck H]

You sure? How about a circuit schematic? Tubes are just tubes. Not necessarily power tubes. How can we (the forum) know what you're showing us?

[Jammin'John]

SE,class A,cathode bias.
28 watts. Baxandall EQ.

JJ

[Leo_Gnardo]

SE,class A,cathode bias.
28 watts. Baxandall EQ. JJ

Looks mighty good! I'll bet it sounds a treat. What output transformer & tubes are you using?