Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: atmars on March 20, 2024, 11:13:27 pm

Title: Identify hifi output transformer taps
Post by: atmars on March 20, 2024, 11:13:27 pm

I have a UTC S-15 output transformer that I believe was intended as a hifi unit. Anyone have any idea what the taps are? I amp guessing the top row is the secondary taps labeled with how many ohms on each tap. If so, what is going on with the primary side? Thx!

Title: Re: Identify hifi output transformer taps
Post by: PRR on March 21, 2024, 01:03:10 am

> believe was intended as a hifi unit

"popular price P.A. service"

https://www.technicalaudio.com/pdf/UTC_United_Transformer_Corp+TRW+OPT/UTC_United_Transformer_Corp_Type_S_terminal_arrangements_1954.pdf

http://www.tubebooks.org/file_downloads/utc_data.pdf

http://www.junkbox.com/electronics/utc_transformer_catalog_1963.pdf

The primary center-tap is not in the physical center.

Title: Re: Identify hifi output transformer taps
Post by: sluckey on March 21, 2024, 10:08:05 am

S-15

Title: Re: Identify hifi output transformer taps
Post by: atmars on March 21, 2024, 10:53:21 pm

Wow! Thanks gents! I had found a little bit of one of those documents, but not enough to get to the bottom of it. I knew there had to be some logic to it that was common knowledge to people on this forum. Thanks again!