Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: WillieBoy on January 24, 2011, 04:37:08 pm

Title: Changing Vibrato 250K Potentiometer from Linear to Audio on AB-763
Post by: WillieBoy on January 24, 2011, 04:37:08 pm

If I change it what will be the difference?  I have notes to change out one of the potentiometers from Linear to Audito, I believe the reverb.

As far as I can tell, changing the pot on the Vibrato should just mean I get less adjustment to about 1/2 way (less fine adjustment).

Thoughts?

Title: Re: Changing Vibrato 250K Potentiometer from Linear to Audio on AB-763
Post by: sluckey on January 24, 2011, 05:04:52 pm

Which pot are you talking about? AB-763 uses 50K-RA and 3M-RA on vibrato (tremolo). The tone controls are 250K, but they should already be audio taper.

If you are talking about Hoffman's AB-763 with bias modulating tremolo, then you are right.

Title: Re: Changing Vibrato 250K Potentiometer from Linear to Audio on AB-763
Post by: WillieBoy on January 25, 2011, 10:37:43 am

Sorry, yes, the Hoffman board.  On that layout, the intensity control is a 250K Linear

Title: Re: Changing Vibrato 250K Potentiometer from Linear to Audio on AB-763
Post by: PRR on January 25, 2011, 01:06:45 pm

"5" on the dial would be 10%, not 50% intensity.

10% amplitude variation is small to the ear. Less would be nearly nothing.

My feeling is that 1-4 would be too small/subtle to notice, half the dial pretty useless.

If you live on BIG trem, this is dumb. If you thrive on very slight trem, it could be worth a try.

It's a 5-minute experiment. No loss if it does not work out, you can use the pot for something else.