power transformer to audio output transformer

[christos]

as the title says..can i make a power transformer 230v to 6-0-6v as a audio output transformer??if i can..then would the secondary coil be the input of the audio?

[woodchips]

Presumably valve? Not if class A, there is substantial DC current flowing that will saturate the transformer, fizz, pop!

I have never tried it, one day, but for class B why not? The DC currents should be equal and opposite so cancel, leaving the transformer happy. A toroidal transformer will be better than an EI type for frequency response. Might even be possible to use a thin cutting disc to make a slot so usable on class A?

Have wondered why you can't use a standard transformer, and buck the DC current with an opposing current through another winding. Seems a reasonably simple bit of servoing, measure HT DC current and then provide the exact opposite? Will it work? Why not?

[SeanB]

Try looking for 100V line transformers, they might be capable of handling DC through the primary. If you use a transformer with 2 115V primary windings and run the valves in push pull with a 100V HT rail then the current will cancel out in the core and you will get better linearity.

[christos]

hard to find a 100v...i just wanned to know if its possible..if not ill buy one..5 euros only

[T3sl4co1l]

Again, assuming this is for valves/tubes (you didn't mention), you can use a 115-0-115 primary in a PP circuit with reasonable results.

Unless it's a toroidal type, don't expect useful bandwidth.

Tim

[Tac Eht Xilef]

Have wondered why you can't use a standard transformer, and buck the DC current with an opposing current through another winding. Seems a reasonably simple bit of servoing, measure HT DC current and then provide the exact opposite? Will it work? Why not?

This was occasionally done in very early valve radios - not really as a servo, since there was little/no feedback (at least not completely deliberately) - by incorporating the filter choke for the HT supply (usually between the CT & gnd) into the output transformer to cancel out the field caused by the DC component of the class A output stage.

It was as big a pain in the arse as it sounds...