Author Topic: Blue dial inside F-2B - gain adjustment? (Read 333 times)

rv_bass · « **on:** January 20, 2019, 01:15:58 PM »

I have a '77 F-2b and I noticed the blue dial inside when changing the tubes today. It looks like it might be a gain adjustment, but does anyone know for sure? I checked the FAQ page and did not see a reference to this dial. I didn't fool with it, since the preamp sounds good with the dial where it is currently set. Thanks!

JimmyJ · « **Reply #1 on:** January 20, 2019, 02:24:08 PM »

My wild guess is that it's related to the lower voltage side of the power supply and not the audio chain (or there would be two). Mica can confirm.

Jimmy J

rv_bass · « **Reply #2 on:** January 20, 2019, 03:26:45 PM »

Thanks, Jimmy.

gtrguy · « **Reply #3 on:** January 22, 2019, 12:43:19 PM »

Trimmer pot going to the tube heaters, I wonder?

mica · « **Reply #4 on:** January 22, 2019, 05:54:59 PM »

Hum balance control. You only might need to change when you change the tubes, since each set of tubes is a little different.

rv_bass · « **Reply #5 on:** January 22, 2019, 06:04:03 PM »

Awesome, thanks, Mica!

Author Topic: Blue dial inside F-2B - gain adjustment? (Read 333 times)

rv_bass

Blue dial inside F-2B - gain adjustment?

JimmyJ

Re: Blue dial inside F-2B - gain adjustment?

rv_bass

Re: Blue dial inside F-2B - gain adjustment?

gtrguy

Re: Blue dial inside F-2B - gain adjustment?

mica

Re: Blue dial inside F-2B - gain adjustment?

rv_bass

Re: Blue dial inside F-2B - gain adjustment?