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Alembic products => Alembic Basses & Guitars => Topic started by: rv_bass on January 20, 2019, 01:15:58 PM

Title: Blue dial inside F-2B - gain adjustment?
Post by: 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!

Title: Re: Blue dial inside F-2B - gain adjustment?
Post by: JimmyJ 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

Title: Re: Blue dial inside F-2B - gain adjustment?
Post by: rv_bass on January 20, 2019, 03:26:45 PM

Thanks, Jimmy. :)

Title: Re: Blue dial inside F-2B - gain adjustment?
Post by: gtrguy on January 22, 2019, 12:43:19 PM

Trimmer pot going to the tube heaters, I wonder?

Title: Re: Blue dial inside F-2B - gain adjustment?
Post by: mica 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.

Title: Re: Blue dial inside F-2B - gain adjustment?
Post by: rv_bass on January 22, 2019, 06:04:03 PM

Awesome, thanks, Mica!