Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: sluckey on March 26, 2023, 06:38:58 am

Title: Vox AC-15 Vibrato channel low volume
Post by: sluckey on March 26, 2023, 06:38:58 am
You've probably noticed that the Vibrato channel volume is significantly lower than the Normal (EF86) channel volume. Here's a simple mod to fix that...

     http://sluckeyamps.com/VAC15/Vox_AC15_mods.pdf

See page 2.
Title: Re: Vox AC-15 Vibrato channel low volume
Post by: JPK on March 26, 2023, 08:10:48 am
Pesky electronics student [dumb] question: Does that jumper also essentially make C25 not in the circuit anymore since it's shorted? 
Title: Re: Vox AC-15 Vibrato channel low volume
Post by: sluckey on March 26, 2023, 08:31:45 am
correct
Title: Re: Vox AC-15 Vibrato channel low volume
Post by: sluckey on March 27, 2023, 08:19:50 pm
Guys, I should add. Although this looks good on paper, I've never verified it. Hoping one of y'all will lead the way.   :wink:
Title: Re: Vox AC-15 Vibrato channel low volume
Post by: Jalmeida on May 06, 2023, 11:03:24 pm
Quote from: sluckey on March 27, 2023, 08:19:50 pm
Guys, I should add. Although this looks good on paper, I've never verified it. Hoping one of y'all will lead the way.   :wink:

I am wrapping up my AC15 and am contemplating trying this.
Title: Re: Vox AC-15 Vibrato channel low volume
Post by: sluckey on May 07, 2023, 07:31:48 am
Please let us know how this works for you.
Title: Re: Vox AC-15 Vibrato channel low volume
Post by: Jalmeida on May 07, 2023, 03:56:06 pm
Quote from: sluckey on May 07, 2023, 07:31:48 am
Please let us know how this works for you.

Honestly I am shocked by how quiet the channel 1 is. But I am not sure that this is design as much as I may have another issue. It is a 1/4 of the channel 2 volume. Sounds like an AC4 in volume. I will flush out any and all existing problems first.
Title: Re: Vox AC-15 Vibrato channel low volume
Post by: EricR on May 31, 2023, 10:21:18 pm
Quote from: sluckey on March 26, 2023, 06:38:58 am
You've probably noticed that the Vibrato channel volume is significantly lower than the Normal (EF86) channel volume. Here's a simple mod to fix that...

     http://sluckeyamps.com/VAC15/Vox_AC15_mods.pdf

See page 2.

Im making progress on mine. Ill try it. I only got 2 resistors close to the 62k value. One at 67k and one measures at 55k. You think one of these is close enough? at least to test it. Can always order one.
Title: Re: Vox AC-15 Vibrato channel low volume
Post by: sluckey on May 31, 2023, 10:31:13 pm
Those are fine.