KT88 in SE Config for Max output

[BJosephs]

I've been modding cheap SE EL84 amps lately and I was thinking about turning one into a louder amp than it was intended. New iron is no problem I suppose, but I don't have too much room for more than one octal tube.

KT88 has the highest plate dissipation values from what I've seen, can it deliver a greater output power as well? Could I pull more than 10 watts out of it in a single tube, single ended configuration. If so, any suggestions on starter values for B+, OT Primary, bias current.

I'm looking for a loud reproduction amp to plug the dummy load output of an over driven EL84 amp into.

If KT88 is not the right choice I can probably fit two 6V6 in for about 20-30 watts right?

[DirtyGeorge]

To get the max power from a KT88 (~15w) you would need to change the PT and OT. Off the top of my head, with plate at 300v you would need idle current of ~120mA. The OT would need to be massive (and expensive).

If your goal is clean power then an AB1 p-p is a better choice. You would still need to change OT but a p-p OT would be much smaller (and cheaper).

[Steve Conner]

I've managed to make one of these a bit louder by fitting a larger O.T. and plugging into a big extension cabinet. Having said that, it was an old Selmer Corvette with about the smallest O.T. I'd ever seen used with an EL84. Another amp with a more sensible sized O.T. might not notice so much difference.

I think hooking up to a 4x12" probably makes as much difference as upgrading to a KT88. And like the previous poster said, you need bigger iron to get the capability of the larger tube. Look at the size of the transformers in the THD Univalve to get an idea of what you'd need.

[Russ]

Parallel OTs

Is it possible to run 2 OTs in parallel to get the current carrying capacity for SE?

For example the Hammond 125DSE model takes 70ma and only weighs 2 lb. Two of these in parallel could handle 140ma which would be enough. The next one up 125ESE (3lb) handles 80ma, even better.

[mooreamps]

I use this tube in my 36 watt amp running SE with another tube. I think you can get by just fine with only one 125ESE. Also, don't be conserned with the plate voltage. It can handle 600 volts or better, no problem.


-g