In article , Nick Gorham
wrote:
Wally wrote:


Does that mean that the specifics of the lay-up aren't too critical?


As far as I know, based on talking to someone who does wind his own,
everything is critical. And until you have built it, you just don't know
how it will work out. The commercial makers have years of experience
behind them, that lets them know with good accuracy what its going to
end up like.

I suspect that the optimum design is a nightmare of 'trade offs' and
'experience'. I'm certainly no expert on power amp audio transformers, but
I think one of the problems is the inter-winding capacitances.

The interleaving helps reduce the shunt capacitance across seen across each
secondary or primary, but tends to increase the link capacitance between
primary and secondary. These all affect the impedance of the transformer at
HF, so can have a serious influence on HF power delivery or amplifier
stability.

I think you can also trade-off 'sectioning' the transformer with
intervleaving. This means effectively using sets of windings that are 'in
series' magnetically on the same core. You also have to worry about things
like heating, risk of flashover at the ends of the windings or through the
insulation, etc, etc.

At the other (frequency) end, of course, you get problems with saturation
non-linearity and finite winding coupling, leakage, etc.

Personally, I was always quite happy to work on SS designs and avoid the
above nightmares. :-)

Slainte,

Jim

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