Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: steven on December 16, 2014, 10:52:01 am

Title: Hoffman AB763 tremolo footswitch pops
Post by: steven on December 16, 2014, 10:52:01 am

Hi folks -

I've built two Hoffman AB763s (a Twin, and a single channel DR) and they sound great, they are quiet, they are my favorite amps.

I have a problem though with the tremolo footswitch in both amps. Sometimes when I switch tremolo off with the footswitch, there is a pop. This seems to happen only if I turn it off within a couple of seconds after turning it on; if the trem is on for maybe 15 seconds or more, it doesn't pop when I turn it off.

I thought this might be because I am just grounding through the sleeve into the chassis, but I still get it if I run a ground wire from the sleeve to the same spot on the ground buss where the tremolo oscillator is grounded. The jack isn't isolated from the chassis, obviously - I should probably install some isolating washers and run the wire again.

I'm at a loss. I've been through the wiring with the layout and a marker, and don't find any errors. If anybody has any suggestions, I would be grateful.

Steven

Title: Re: Hoffman AB763 tremolo footswitch pops
Post by: EL34 on December 31, 2014, 10:07:25 am

Hard to say


Maybe the switch contacts are bouncing?

Title: Re: Hoffman AB763 tremolo footswitch pops
Post by: Willabe on December 31, 2014, 10:31:37 am

Quote from: steven on December 16, 2014, 10:52:01 am

This seems to happen only if I turn it off within a couple of seconds after turning it on; if the trem is on for maybe 15 seconds or more, it doesn't pop when I turn it off.

I know that when guys build an amp, myself included, we want it to be as perfect as it can be, but......

I'm not sure you would have even found that click if you hadn't built the amp yourself and were putting it through it's paces testing it?

I love tremolo and use it, but I can't think of a situation where I would only need to have it on for 15 seconds or less in a song.

If you find it/fix it great but I'm not sure you even need to?


                     Brad     :icon_biggrin:

Title: Re: Hoffman AB763 tremolo footswitch pops
Post by: steven on January 07, 2015, 10:54:19 am

Thanks for the replies; yep, I decided I wouldn't spend too much time with it. It really has no practical disadvantage. Next time I have the amp open I will see what I can see. There must be a DC voltage difference of just a bit.

steven

Title: Re: Hoffman AB763 tremolo footswitch pops
Post by: EL34 on January 07, 2015, 12:37:14 pm

There might be a way to add a capacitor and have it discharge the contacts


I have never done it
Maybe someone here has an idea