Hi,
Just wanted to follow up with comments about how the transformer worked. It worked very well.
I ordered the EA60 (60W, 4 & 8 Ohms, 70V & 100V isolated audio transformer) from Edcor, $28.20. I got the 60W size but probably the
30W would have worked OK, but I figured "bigger is better" when it comes to audio. Isn't that the case with many things, though?
It came in about 2 weeks.
Where the 60Hz power transformer I tried first was sharply resonant at
60Hz (as expected), the EA60 showed pretty flat response from 20 Hz (they only claim 35Hz) to about 5 kHz. Then it begins to droop a little at my 10 kHz test point (voltage waveform was -2 dB), but is still working well at 20 kHz (-5 dB). Some of this is due to my amplifier's characteristics, though. To save time I'm not making careful measurements.
Surprisingly the ancient 6x9" Jensen JCX-240 "Coax" I am driving as a test speaker sounds decent. It must be > 20 years old.
Thanks for the many replies and suggestions.
mw