Mesa Mark amp, converted to EL34s?

[kramerxxx]

I read a post recently where a guy with a Mark IV Simul-Class amp had the inner power tube pair converted to EL34s. Has anyone done this with other Mesa Mark amps and if so, could you provide some detail on how you accomplished this?



From what I gather this was just screen grid resistors and the tubes, but I'm not sure.



On my Mark V I run all EL34s and it really makes the amp shine, over running 6L6s, IMHO. I'd like to do this with my Mark III.

 

[igfraso]

Some years ago, I bought a Mark III purple stripe combo 60 watt and fully loaded (export transformer, rev, EQ) and I asked Mike B. to make the necessary changes so I could use it with 2 x EL-34, instead of the usual 6L6 (he also adjusted the bias for the new tubes and added the R2 volume pot at the back of the chassis).

I don't know what he did but he changed the class AB pentode power section into a class A triode. Now, it a a 25 watt amp.

To my old ears (disclaimer), the cleans sound a little bit more hairy with more mids and less bass.
Crunch channel sounds smoother with more mids, maybe a little bit more compressed.
Lead channel sounds very nice as well with less bottom end and a more rounded top end.

I also had to change speakers because now the speaker jacks are labeled 8 ohm, 8 ohm and 16 ohm instead of the usual 4 ohm, 4 ohm and 8 ohm.
I installed an Altec 417-8B (16 ohm speaker) and it sounds very sweet.

Again, this is how it sounds to me.
Thanks
Daniel