Fender Twin Reverb OPT

[CJ]

is it a combo amp or just the head?

if it a head, then they probably wanted the option to run a Marshall  4 x 12 type of cabinet,

got done rewinding this guy , managed to get all the wire on but used #21  instead of #19 for the speaker wind so as to be sure we would have enough winding room,

a little more DCR is not going to drop much power and even if it did, that would be kind of a blessing for an amp this loud,

the transformer was a bit more lively as far as resonant peaks, instead of dropping off slowly, we had a couple of peaks at around 100 K hz and 700 K Hz,

could be because of the reduced capacitance of the #19 wire, could be the varnish, but i suspect it is the Nomex insulation we used instead of the poly insulation as the Nomex has a different dialectic constant and thus changes the capacitance, or it could be because we used 7 mil Nomex instead of 3 mil poly for the pri to sec insl.

Nomex gives you 1000 Volts per Mil insulation so we have 7 KV of insl plus the 3 mil KP between pri/sec.
and the nylon bobbin will improve arc over between coil and core.

 

[CJ]

here is the print with some rewind info shown in red>

 

[clintrubber]

is it a combo amp or just the head?

if it a head, then they probably wanted the option to run a Marshall  4 x 12 type of cabinet,

Guyatone did both combo & head formats and there doesn't seem to be a clear approach wrt OPT taps.
Possibly their earlier clones did just have one tap and later ones got an additional tap.
The shown circuit-snippet is from the GA-1100D which is a combo (TR clone), and this same OPT-type also appeared in for instance their Bass Man heads. Like you said, makes sense, especially for separate heads.

Strange actually that original Fender heads like the Dual Showman Reverb didn't bother to feature more than one tap, but were possibly not considered to be needing one. OK, enough Guyatone derailing, we're back @ Fender, again, great info you provided here.

Cheers