Transformer for OTS type circuit

[shane]

So I've been looking at Koch amps OTS circuit which uses half a 12ax7 as a small power amp to get a switchable poweramp style overdrive.
Just wondered if anyone had any thoughts on the likely specs of the transformer. I wondered if the standard fender type reverb tranny might work.
Cheers
Shane

[Stevem]

The Fender reverb drive transformer is looking for the RA value of both sides of a AT7 in parallel and the bigger current gain of the AT7 over the AX7, so i don’t think it will fly too well, but others here may know better?

[teemuk]

Finally seeing the "OTS" circuit I must say I'm dissapointed. Eventually no different than what Hafler or Crate did more than 30 years ago and even in the 1970's there were far better "tube power amp" emulations built entirely with semiconductors.

A single-ended common cathode amp stage with token transformer coupling. Not any element from which tube power amps traditionally get dynamics and touch sensitivity in sight. It won't sound even remotedly like an overdriven Marshall or any other legendary tube amp. Why bother?

[shane]

Well, after listening to Greg Koch demo his 'The Greg' amp I thought it sounded quite good, just added a bit of extra oomph and body.
I didn't know that Hafler or Crate had done it before do you have any idea which of their amps they put it in? I'd still like to try it and complicated solid state circuitry is not really my thing.
Still like to know some opinions on a transformer that would do it!
But thanks for the replies guys much appreciated

[mhuss]

Well, the "Fender 22921" listed on the schematic is a standard reverb driver transformer, available lots of places. Why not just use that?

[shane]

oh heck, do you know I never even noticed that!
Probably because I was initially looking at the pedaltone 1 which has a slightly different circuit configuration which doesn't mention the tranny, and only downloaded the pedaltone 2 one just before I posted on here.
Oooh I feel such a fool
Thanks Mark, any chance I can borrow your eyesight another time
Cheers
Shane

[teemuk]

I didn't know that Hafler or Crate had done it before do you have any idea which of their amps they put it in?

Well, at least T2 preamp (Hafler) and GT-80 (Crate).

[shane]

Thanks teemuk