just wondering

[bigsmitty]

Has a ny body ever built a push-pull amp using two different tubes, say like a 6l6 and an el34?

[xtian]

Different PAIRS of tubes, yes. My Mesa Boogie Mk IV has EL34s and 6L6s in it. The Egnater heads have different pairs with a Blend control.

Never heard of using different tubes as a pair, because...um...what would happen if two mismatched people were pedaling on opposite sides of a single bicycle? One would burn out. OK, bad analogy. Someone else will explain!

[bigsmitty]

If they had a separate bias adjustment you could even them out?

[selloutrr]

yes

[martin manning]

With a bias adjustment for each side you could even out the idle current, but they would not be matched when signal is applied.

[selloutrr]

it's very common to run KT77 and EL34 in 100Watt each type needs to be in matched pairs.

so you would tube the amp KT77 EL34 EL34 KT77 or vise versa

[martin manning]

Seemed to me like the OP was asking about a push-pull pair using two different types. A quad with one of each type on each side would be fine of course, as long as there were two (or four) bias voltages available.