Will this output transformer work?

[Chuck H]

I second the 400V. It's not low enough to cause a tonal compromise, new production tubes will be less likely to have trouble and IMHE is just about as good as it gets for clipping in both wattage and tone. Examples of amps with roughly 400Vp on a pair of big bottles at idle:

50W Marshall JMP's from the 70's
Trainwreck Express
Matchless Clubman
and several tweed and blonde Fender classics between 380V and 420V

Hard to go wrong

[TarheelTechinTraining]

Thanks for the encouragement fellas. 6l6s are a good suggestion but I already have a pair of e34ls to work with. Just for giggles what would I need to change to run 6l6s?

[Chuck H]

Your OT and voltages are fine for either, the sockets can be wired to accept either and the typical 470R individual screen resistors should be ok for EL34's at 400Vp or you can just use 1k screen resistors as per most recommendations for EL34's and the difference for 6l6's shouldn't be noteworthy. So the only thing left is to make sure your bias supply is adjustable for either. You'll probably want a range of -30V to -60V for a fixed bias supply.

[TarheelTechinTraining]

I'm using 1k screen resistors. But something has me confused. For bias do I use 22k pot or 50k? I have 2 different schematics of the same style amp.

[The Dude]

That's going to depend on the rest of the bias circuit. There is usually a series resistor associated with the pot. Are they both the same in the two different schematics? Can you post the schematics?

[Chuck H]

Right. What he said ^^^^^^^^^^^^^^^^

It's probable you won't be using the exact PT for either of those amp schematics. In which case there may be other differences. You can use about any bias supply that's known to be reliable and works with your rectification and windings but you'll probably need to adjust resistances to tune the circuit because it works in relation to specs that may be particular to your amp.

[The Dude]

The key thing, as Chuck mentioned above is the bias range. Before you install the output tubes, you are going to want to check and see if you can swing the bias from approximately -30V to -60V. This will be dependent on transformer output, resistor and pot values, etc. You may have to do some tweaking to get it right.

[TarheelTechinTraining]

Thanks, Dude. That's kinda what I figured. Greg

[überfuzz]

Do you have any preferences when if comes to guitar sound(s)? Do you have any idea whether you and your band play loud or not...

What kind of music are you normally playing? Maybe we could sugest some amplifier schematics that you model your build around.

[TarheelTechinTraining]

I play mostly hard rock but more than anything I'd love a solid tube amp. BTW I must have read my meter wrong about my PT secondary I have 300 vdc after rectification.

[Chuck H]

I play mostly hard rock but more than anything I'd love a solid tube amp. BTW I must have read my meter wrong about my PT secondary I have 300 vdc after rectification.

Unloaded?

Any known information about the PT might be good to know now. Where did it come from, approx. size, center taps, number and voltages of windings, etc.

[TarheelTechinTraining]

Yeah unloaded. The PT came with the OT, a jtm 60.

[Chuck H]

Ok then. I'm finding the JTM60 schematic frightfully hard to interpret. Maybe someone else can make more sense of it.

In the meantime I'm suspecting a mistake in the hookup. Tell us about your rectifier circuit. Primary connections? Can you measure the AC on the 6.3V winding to confirm accuracy?

[TarheelTechinTraining]

That jtm was a nightmare to read, ain't it. Its 7.2 on the heaters. There is an extra secondary of 43 vac probably for switching and such.
My rectification is (4) 1n4007 for DC positive

[Chuck H]

My rectification is (4) 1n4007 for DC positive

Arranged as a bridge rectifier then? With a 0V reference?