Anybody ever see or hear an amp with these installed on it? It says with an amp with 6v6's it will actually increase it's output? Price is a little on the high side though, but it's a very interesting idea.

http://www.thdamps.com/pdf/yj.pdf

http://www.mercenary.com/thdyejatuco.html

The power output difference between 6V6s and EL-84/6BQ5s is so small that I doubt it would really be noticable. Sounds like this is for Geetars only and wouldn't work well in audio apps.

In my experience, those are mainly just used for changing the sound of guitar amps. A friend of mine put 'em in his Fender Bassman, because the EL84s tend to break up more/differently when over driven, and that's the sound he was looking for. Basically it gives more of a vintage tint to the sound. I suppose they'd work in audio equipment, but it wouldn't be hifi.

What interested me was the fact that you could run EL84's in Class A mode. That I would think would be Hi-Fi? I guess it would depend on the circuit inside the adapter. Still seemed like an interesting concept and would definitely change the sound, but who knows for the better? They have a quad setup also, now I know guitar amps are made to be overdriven, but that would be more with the driver tubes? This is just the outputs.

*Bangs head on table.* You're right, I don't know what I was thinking about... Maybe I should try sleeping sometime, people say it has good results... Anyway, yeah, it would depend on the circuitry in the amp, but I still have doubts that you'd gain any advantage over just using the tubes the amp was designed for. Now it's got me curious, too, though. Somebody with more money than me (and who has a 6v6 amp) should try this and tell us the results. :D

Here is a little more info on the circuit inside the adapter. http://www.blueguitar.org/new/text/yellowjacket.pdf

But what do you get with the additional componenets. This would be a quick fix. For Hi-Fi audio, rebuild the circuit yourself and see the results.
Ron

Class A means SE and there are many audio and guitar amps out there that use this topology. I don't play guitar but isn't a Fender Champ a single 6BQ5 and a 12AX7?

I used to have some amps that used the old 50s Mullard 3.3 circuit which is SE with a EF-86 driving a EL-84/6BQ5. I thought they were great blocs but the little EF-86 pentodes have a tremendous gain to them. I drove 92 db Shahinian Obelisks with them and it was my first at home audition of SE tubes. Twas all it took. I like good PP but I love good SE.

Class A does not mean single ended. Class A means that the output devices are biased "on" all the time (working -- dissipating full power -- whether passing signal or not). Class A PP is not uncommon at all... indeed virtually all modern SS PP amps run "class AB" (i.e., class A at low power levels and class B at high levels). The best Yamaha PP amps of the 1970's had switchable Class A output... you could cook on 'em, but they sounded really good.