Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Kesi from Hungary on March 05, 2024, 11:34:00 am

Title: Vox AC4 switch question
Post by: Kesi from Hungary on March 05, 2024, 11:34:00 am

Hello,
I am busy with an Ac-4 build and there is still a footswitch missing that still needs to be ordered along with some other parts. I want to test the vibrato channel and currently only have a 3 pole on/off switch.
Is this also possible and how should I connect it to the wire that comes from between the 0.01uf caps? I tried some options yesterday but couldn't figure it out. :dontknow:

I used the original schematic and the layout from Sluckey

Title: Re: Vox AC4 switch question
Post by: Kesi from Hungary on March 05, 2024, 11:50:43 am

This one

Title: Re: Vox AC4 switch question
Post by: sluckey on March 05, 2024, 11:59:07 am

You don't need a switch to test the tremolo. The tremolo is on by default and a switch is used to turn the tremolo off. Your blue switch will certainly turn it off. Just connect the footswitch wire to the center lug and connect a ground wire to either of the outside lugs. If you want a real footswitch I recommend this one (https://www.tubesandmore.com/products/footswitch-box-marshall-one-button) from AES.

Title: Re: Vox AC4 switch question
Post by: Kesi from Hungary on March 05, 2024, 02:49:18 pm

I mounted the switch and heard a small difference when I turned the intensity. He tried to get going for a little second, but actually it seemed more like a tone knob when turning. The speed knob did nothing. I think I was on the vibrato chanel during this action, but nothing changed when switching. Yesterday I had no response at all to the intensity knob. I must have made a mistake somewhere when making the amp.

It's my first build. A conversion of an old tape recorder to the AC4. Tag strips were used, so it actually became more of a point to point. I have tried to stick to Sluckey's original layout as much as possible because I have little experience yet. I'll post some photos. Maybe something is visible.

There is now a temporary champ OT in it and the 2x32uf on the choke still needs to be replaced by a can cap from JJ. Initially I had an EZ80 and a 1k resistor on the 32uf ​​caps, but the voltage of the Power transformer was only 230 VAC and therefore only had 223 DC on A. After installing an EZ81 and the original choke of the tape recorder I came at 262 DC at A and 254 at B

Title: Re: Vox AC4 switch question
Post by: Kesi from Hungary on March 05, 2024, 02:55:28 pm

some more pictures.

and forget to tell you that the knobs are in reverse order

Title: Re: Vox AC4 switch question
Post by: PRR on March 05, 2024, 03:43:45 pm

https://el34world.com/Forum/index.php?topic=19361.0
!!!

Title: Re: Vox AC4 switch question
Post by: Kesi from Hungary on March 05, 2024, 11:18:08 pm

Okay. I understand. I'll draw it by hand.