Tube Power Amp: Integrated Quads?

Tom Gorr · Post by **Tom Gorr** » 9 May 2005 6:03 am

Does anyone here have any experience with putting different power tubes on the "outside" (top? second stage?) of the power amp circuit compared with the tubes on the "inside".

Thought there might be some benefit in hitting a Rock/Country hybrid - for instance using a set of 6L6's on the inside in conjunction with a set of EL34's on the outside.

Perhaps it would be even better to somehow piggyback two totally different valve bands that you could switch depending on your tone/breakup requirement.

I understand that Mesa might do something like this in their simul-class power amps, but wanted to know a bit more about these concepts on a theoretical level.

Thoughts ?<font size="1" color="#8e236b"><p align="center">[This message was edited by Tom Gorr on 09 May 2005 at 02:48 PM.]</p></FONT>

Jerry Erickson · Post by **Jerry Erickson** » 9 May 2005 7:31 am

I've never done it but you'd need to be able to adjust the bias indepndently for the 6L6's and the EL34's as they have different idle current requirements.

Dave Grafe · Post by **Dave Grafe** » 9 May 2005 9:02 am

While I have in past lives substituted 6L6 tubes for the 6V6 found in small amps, I would not recommend mix-and-match power tube experiments with your tube amp. The different impedances, gain factors, etc. of various tubes are NOT compatible and you could end up sending a lot of current to places where your amp isn't designed to handle it.