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Hoffman Amps Forum image Author Topic: Vox AC-15 Vibrato channel low volume  (Read 2862 times)

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Offline sluckey

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Vox AC-15 Vibrato channel low volume
« 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.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline JPK

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Re: Vox AC-15 Vibrato channel low volume
« Reply #1 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? 
I love tubes

Offline sluckey

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Re: Vox AC-15 Vibrato channel low volume
« Reply #2 on: March 26, 2023, 08:31:45 am »
correct
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline sluckey

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Re: Vox AC-15 Vibrato channel low volume
« Reply #3 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:
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Jalmeida

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Re: Vox AC-15 Vibrato channel low volume
« Reply #4 on: May 06, 2023, 11:03:24 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.

Offline sluckey

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Re: Vox AC-15 Vibrato channel low volume
« Reply #5 on: May 07, 2023, 07:31:48 am »
Please let us know how this works for you.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Jalmeida

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Re: Vox AC-15 Vibrato channel low volume
« Reply #6 on: May 07, 2023, 03:56:06 pm »
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.

Offline EricR

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Re: Vox AC-15 Vibrato channel low volume
« Reply #7 on: May 31, 2023, 10:21:18 pm »
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.

Offline sluckey

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Re: Vox AC-15 Vibrato channel low volume
« Reply #8 on: May 31, 2023, 10:31:13 pm »
Those are fine.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

 


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