Larger transformer?

[EniGmA1987]

I am looking for a transformer that could put out about twice as much power, so it could power two 12AU7 and two 6080 tubes (basically making two crack's in one chassis for a balanced dual mono amp with dual XLR input to replace the RCAs and a 4-pin XLR output to replace the 1/4" TRS). I suppose I could use two transformers, but that takes a lot of space and Id rather use 1 transformer if I could. Would a transformer with a 120V, 60Hz line to 350V (175-0-175) at 60mA center tapped and 6.3V (3.15-0-3.15) at 2A center tapped work in the crack? It has 25v higher on each of the windings, but I already upgraded the PSU filter caps to 300v capacitors so they are rated higher than the stock caps. It also looks like it has more than twice as much power if I am reading the stock transformer correctly for its 25ma on the label. Here is the manufacturer page for the transformer I found: https://www.edcorusa.com/xpwr024. Would the bit higher voltage be a problem? Would I be able to raise the 5w resistor values to lower the voltage back down and everything would be good?

[mcandmar]

Curious.  Personally if i was going to that much effort i would use separate transformers and power supply for the left and right channel, i.e. monoblocks.

Keep in mind the filament current is high, over 3amps in total so that little transformer isn't going to be any use.

[Paul Birkeland]

I've done this experiment, with a very large transformer, and the results were horrible.  It was actually a project that put me off so much that I abandoned the Crack type headphone amp circuits for a few years.

If you want to repeat the experiment, grab a dedicated 6.3V transformer with 6-10A of current.  The PT-3 in the Crack can provide sufficient high voltage current to run two 6080's.

-PB

[EniGmA1987]

I've done this experiment, with a very large transformer, and the results were horrible.  It was actually a project that put me off so much that I abandoned the Crack type headphone amp circuits for a few years.

If you want to repeat the experiment, grab a dedicated 6.3V transformer with 6-10A of current.  The PT-3 in the Crack can provide sufficient high voltage current to run two 6080's.

-PB

Hmm. Is the issue the circuit itself is just not suited to run as a balanced type headphone amp? Or is the issue you describe just in relation to the power supply side and with using the single transformer?

[Doc B.]

At some point you probably need to try the idea and listen for yourself, as there enough variables in how this could be implemented that answers to these questions would be speculative. PB's suggestion might be the most effective way to see if there is merit to the concept.

[Paul Birkeland]

Hmm. Is the issue the circuit itself is just not suited to run as a balanced type headphone amp?

Yeah, I would agree with Dan that you should do the experiment yourself.  It's somewhat eye openning.  This is an experiment that could be accomplished by converting two Cracks to monoblocks.

[Paul Joppa]

I will just note that this approach to balanced ouotput doubles the impedance, so instead of 200-600 ohm headphones, you will want 400-1200 ohm phones. There are not many....