What determines output ... OT or PT

[gnugear]

What is responsible for the Trainwrecks 30 watt output? What would happen if you use an existing transformer for a 50 watt Marshall?

[jaysg]

Both and more. Assuming you mean an 50W transformer set, then you'd probably get more power. The circuit itself can change the point of clipping. In the case of the KF amps, the PT's have current to spare, so distortion isn't caused by a flagging PT. For another amp, that might be the limiting factor.

In my mind, a 50W amp is an amp where the power amp starts breaking up at 51W. You can alter the phase inverter of an amp to get more or less clean power. Mismatching the OT impedance can bring it down. Running a higher B+ can pull it up. Output tubes are not equal either. You might see some variation between brands and NOS parts, all with the same designation, i.e. EL-34 or 6L6GC. hth

[Zippy]

What is responsible for the Trainwrecks 30 watt output?

It is dominated by its low (for El34s) B+ voltage.

What would happen if you use an existing transformer for a 50 watt Marshall?

In general, if you're talking PT/OT set, the higher B+ with produce more power, the larger OT will transmit more power before saturating.

[gnugear]

So using a 50 watt marshall output transformer would translate to more headroom but not volume or output, correct?

One more question ... can one build a TW but use a 50 watt transformer set and not change any of the other component values?

[ODwan]

can one build a TW but use a 50 watt transformer set and not change any of the other component values?

Legend has it that this was just what Ken did when he developed the Express circuit: modding Marshalls! I think it was mentioned in a Bio on the old Trainwreck page.