Vintage Fender Construction - Bias Supply

[Fletcher Munson]

On most of the Fender blackface and brownface amps, the bias supply is tucked away on a little board in the corner of the chassis. What's the advantage to having these components (diode, cap, resistor) physically separated from the rest of the circuit? Noise suppression, or were they just trying to pack stuff into unused space?

It seems you could just make the main circuit board a little longer and stick these components on the end. In fact, that's what Fender did on some of their earlier amps with the selenium rectifier (5F8 Twin for example). So, did they find that the bias supply introduced noise into the circuit and moved it away?

[mozz]

Maybe, but also maybe they wanted to standardize the bias supplies across models? Not familiar with the browns. Any good reading about bias supplies and noise?

[Justin Thomas]

I try to keep the bias supply as far away from everything as possible... after that time I used a few extra turrets on my board to switch to fixed, BUZZZZZZZZZZZZ...
But, I do agree that it was probably done to standardize the assembly line. Just make the little bias boards as modules. Fender was all about efficiency of manufacture and ease of production.

Justin