An Idea For Muting the Dry, Parallel Loop with a Mosfet

[afu]

A depletion mode mosfet is closed (on), with no voltage applied to the gate (opposite of the jfets which switch on the FX). My idea is to insert a small circuit to mute the dry path as the voltage is applied to the all the fets' gates when the loop is engaged. The voltage which turns on the jfets would turn off the mosfet. A second mosfet could be placed at the input path of the dry signal to completely remove it, but I'm not sure it's necessary, unless leakage occurs.

I am still looking into how this would work, but I wanted to share in case anyone else has some thoughts. The mixing pot would be removed and it would essentially become a 2 channel loop. All the rotary switch functions would continue to work. Equal size summing resistors could be used as load resistors for each path into v4b and a tiny cap to ground could discharge pops without affecting any frequencies which are of interest.

https://warpedmusician.wordpress.com/2015/06/09/idea-to-be-developed-depletion-mode-mosfet/

 

[afu]

http://www.vishay.com/docs/83805/lh1501ba.pdf

I could make a small daughter board with this and use it to switch off the dry track when the loop is active. Again, I'd remove the return pot from the circuit and have the dry path output and pot-to-V4b input path as the connections.

It's supposed to be a bounce free, quiet switch. All the parts are miniature, self contained, and just needs a limiting resistor to the LED. The only optional requirement could be a voltage regulator, but I don't think that's necessary.

The rotary loop and foot switch/midi TRS should still function just fine, as the loop circuit appears to only have power when the loop is meant to turn on.

Any thoughts? I think I will test it out as on outboard piece to mute the cables from the loop and see how well it works. If a person were so inclined, the various cousins to this chip can switch channels, act as a switch to turn on a loop, be a true bypass, and be used in mods for voicing, gain, or whatever. A new design would probably be better than retrofitting, but these things are awesome. I might use a similar device in my pedal designs.

Any thoughts?

 

[vick1000]

By cutting the dry signal, aren't you just making the loop serial? Mods already exist for that, and can be made switchable. What is the exact function you are trying to achieve?

 

[afu]

Instead of a hard bypass and losing functions on the loop selector or footswitch, it would use the dry path when the loop is turned off. The normally closed switch kills the dry path when power is applied, opposite of what the jfets do at the Send and Return junctions. It's two separate, switching, serial paths with no function loss. If you can show me a mod that does that, please do so, because I don't feel like modding my amp and walking away with less than I started with.

EDIT: Also, this proposed mod only needs one part to do the switch. My other idea was to use it with the Mesa mod to use the footswitch as a mute, since the loop control function is cut from the circuit.