[retailer]

Thanks kalee20 for the detailed post, I'll copy and paste it into a txt file for the time I tackle my own project - I'm not sure what iron (grain orientation, lam thickness etc) will be used in the final transformer, I just happened to have a stack of lams from a transformer I dismantled and intended to rewind as part of the stepper motor power supply for my manual to CNC mill conversion, I have a vague recollection that it came from an old solid state PA amp and was used to drive the 100V audio line, these days 100v lines are outmoded and the usual thing is to use powered speakers, I ended up rewinding a huge toroid instead.

The amp builder wanted the winding leadout wires fed through spaghetti tubing before anchoring and then winding, on one of the transformers I did not not notice that when starting the first secondary winding, the wire had slipped some time prior to anchoring, and I went ahead and finished all of the windings, it was then that I saw the wire wasn't poking out of the spaghetti tube - I cut a short section of the tube off hoping to see the wire, I kept cutting and looking until I had cut off all of the spaghetti tube and still no wire emerged. No option but to unwind it right back and rewind with new wire, I didn't want to chance using the same wire.
For now I'll just hand them over to him and let him worry about the inductance and core gap, if I get invited to a listening test I'll report on how it went.