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Not the switchable one, just 6V6's instead of EL84's. Has this been done? I just got the TMB kit, and was wondering what I would have to change, to run 6V6's. Is there a layout & schematic for such an animal?

I think you can go to the resource area and look at the V6 schematic and just eliminate all the el84 stuff outboard of the PI. ie.no 8k2 grid stoppers, el84 bias components ect. Should be easy! Of course enlarging the o/p tube socket locations would be a pain.
Stew

I think 6V6s can sound pretty nice in an 18W with the regular 8k2 grid stopper. And yes, 18W TMB amps with 6V6s are quite popular.

Basically, you can use 6V6s in any of the regular EL84 18W amp designs just by changing two resistor values. The first is the tail resistor in the PI, which needs to be changed from the stock 56k or 47k to 27k or 22k, thereabouts. Then you change the power tubes' cathode resistors from the stock 125 or 150 ohms to the 6V6 value of 250 or 270 ohms, thereabouts.... Obviously you have to change around the pin numbers on the power tubes to suite the different pin numbering between EL84s and 6V6s. But that's basically all there is to it.

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Is that tail resistor change to drive the 6v6s a little harder? How does the V6 make do, with the 56K tail in the V6 setting?

Yes, you really need to reduce the tail resistor value to compensate for the lower gain of the 6V6s relative to EL84s, assuming you still want the 18W overdriven power tube vibe. However, I think in the V6 the idea is to drive the 6V6s less hard relative to the EL84s, so that they break up less than the EL84s, giving you more of a contrast.

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Great tones come in small glass jars!

Thanks for the replies... This is great... It's the amp that exists in my mind. Tube sockets are no problem, I'll just punch em' out. I have a 22 watt transformer set for a deluxe reverb. This should work O.K. shouldn't it? Everything physically fits...

Yes, the v6 intent is as Phil suggests. Cleaner, smoother but we did try to drive the 6V6 harder with a different PI tail resistor and heard little difference. Suggest you go to the lower limit on that one, but we wanted to switch them in/out.

Works pretty nicely too.

Reference docs in the Resource forum.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

One other thing that's been proven to work well in a 6V6 version of an 18W is to reduce the PI's cathode resistor from 820 ohms to the Plexi's 470 ohms. This also helps get the 6V6 tubes singing. Then that makes a total of three resistor changes.

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Great tones come in small glass jars!

Thanks, I've made notes about the three resistor changes. Any thoughts on speakers this thing would like. I'm thinking a single 12", I'm also looking for light weight. Has anyone tried a neodymium magnet speaker? "Lil' Texas" "Tonker light" etc...

The Tone Tubby San Rafael is a lightweight option that should work with this amp.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Yes, I think it should work. However, you will probably need to use the same kind of octal rectifier that the PT was designed to work with, so that your DC voltages are in the right ball park. If that happens to be a 5Y3, then bear in mind that Sovtek 5Y3s aren't true 5Y3s and will give voltages that are too high. It's also possible to use zener diodes to decrease the B+ voltage some.

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Great tones come in small glass jars!

I've got a couple of NOS 5Y3gt's An RCA and a Motorolla, both from the 60's. One of those should work nicely.