Cathode change via footswitch

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coldengray
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Joined: Wed Sep 28, 2016 8:38 pm

Cathode change via footswitch

Post by coldengray »

Greetings...I have been working on a hot-rodded master volume Marshall style amp and added a vintage/modern switch. I have an unused speaker jack so I was thinking that I could make this feature foot-switchable but I'm having some problems getting it to work correctly. Here is the schematic for what I'm doing, the idea is switch between the classic Marshall value of 10K and 2K7 with .68uf bypass cap.

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Here is how I have it implemented, the switch is an on/on switch. However, I need to use a different switch (on/off?) because I can't footswitch it as it's currently wired. I need advice on the best way to make this feature - switching between 10k and 2k7/.68 - work via foot switch connected to a shorting jack. Or maybe I would be better off with a relay? Thanks for the help!

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pompeiisneaks
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Re: Cathode change via footswitch

Post by pompeiisneaks »

Yup you've got it wired wrong. The connection into it from pin 8 should be to the center of the switch, and then the output of the switch on only one side should connect to the bottom of the 10k. In your schematic, it's just a single switch between the .68 uf cap and ground. You're toggling trying to swap between two different options when really you just need the on/off type switch, unless you're not following the schematic.

~Phil
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coldengray
Posts: 33
Joined: Wed Sep 28, 2016 8:38 pm

Re: Cathode change via footswitch

Post by coldengray »

Thanks Phil. I did this a while ago and I'm just coming back to it now, and I recall wiring it the way I did because I only had on/on switches available at the time...at least I think. Not sure why I put the 100k/10k option in there.
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roberto
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Re: Cathode change via footswitch

Post by roberto »

On top of that, you need to mute the circuit for few ms in order to avoid the loud pop come to your speakers.
coldengray
Posts: 33
Joined: Wed Sep 28, 2016 8:38 pm

Re: Cathode change via footswitch

Post by coldengray »

I think if I change the switch to an on/off and put a 1M resistor across it that will eliminate the popping noise. I am considering an H11 transistor to do this, because I’m already using one for the volume boost...this would allow me to use a single stereo jack and two-button footswitch. I already have a dedicated Boost jack. The goal of all this to give me a cleanish sound so I can use a fuzz the way I want for certain songs. I might experiment with 5k instead of 10k to see how clean I want it. Any advice is welcome!
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roberto
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Re: Cathode change via footswitch

Post by roberto »

The pop comes from the change in polarization, so change in voltage on both cathodes and anodes, not from the cap charge up.
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