Mastersound 300B SET (Vaic) Blown transformer

[DeafbyKhorns]

I have an original Mastersound (Vaic) 300 B amplifier with a blown transformer. Looking for a schematic or someone that can measure the AC output so I can find something to fit the xfrmr case. The US rep won't respond. Looks like fixed bias, probably 400-450v B+. I could probably reverse engineer and take an educated guess but trying to keep the amp as original as possible.
Serial #58
Solid state power supply
12AU7 to 5687 driver tubes
Fixed bias
Mastersound won't respond, MoFi won't respond.
Been emailing for two weeks now.

This is the amp
https://www.stereophile.com/integratedamps/208mast/#xAZqHdiuYzY35jmL.97

 

[Nyjblbob]

400-450V is too high for the best sound from 300B's.
I feel your pain trying to get an match for the X-formers
Just another reason to avoid older, esoteric foreign made amps.

 

[DeafbyKhorns]

Well, the specs say 12wpc so I thought it was a good guess on the voltage.
I'm repairing for a friend and build my own amps, I could reverse engineer but its all on circuit boards...
The transformers are potted into one big can about 8" wide. I could easily remove these and stuff them with a custom.
The HV, bias and 6.3v come from one transformer, a separate xfrmr does the 5vdc supply which uses some large adjustable resistors to set the voltage.

 

[Nyjblbob]

My guess is after melting the x-former out from the Pot
you are going to find a very small x-former.
Good luck ,You might be better off buying a new matched pair of outputs.
Bring the plate voltage down to 350-375 where 300b's sound the best,
and redesign the amp.