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FX Loop wet/dry pedal project. Need to control signal path. Help please.

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Frank_Alias

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I need help making a simple FX loop switch.

I have made it as shown in the images. It has problems.


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The idea is this: I have an "Ibanez echo shifter" analog delay pedal. I have converted it so it has wet signal ONLY. I want to leave it permenantly on, and use the momentary footswitch (or latching toggle) to send a signal through it. This way, when I release the footswitch I can continue playing a dry signal over the top while the trails of the delay continue. I also prefer the momentary action as I find it more musical than clicking on and clicking off.


https://i.ibb.co/nnRPNyy/fxloop-photo.jpg

The dry signal is uninterrupted. It is never broken. This was to ensure continuous smooth tone. The loop is meant to create a wet signal in the modified Ibanez and then blend wet and dry signals back in the fx loop pedal, before sending the signal out to the rest of the signal chain.


https://i.ibb.co/jHrv8LD/fxloop-diagram.png

The problem: the design of the fx loop means that there is additional feeding back. When the "feedback" setting of the Echo Shifter is at minimum, the result is more as though it were at 70% . When the "feedback" setting is at maximum, there is rapid building up of signal and in many cases it is unusable (sounds cool but not correct).

This is because the "return" jack is directly connected to the "in" jack and it makes the repeats go on for longer (only as long as the footswich is pressed or toggle flipped "fx on").

So I know I should control the flow of signal... Diodes right?

I took a diode - I had some lying around from something years ago. I put it in position "A" to make the signal flow "in" to "out" but not from "return" to "in". I DO want it to go from "return" to "out" to blend the wet and dry signal.

OK the diode just stopped the signal altogether. It just stopped it. Tried it both ways, but I know which way the signal flows. This diode just stopped the signal completely. Now maybe there are different values of diode and I should try something else. I don't know enough about electronics. I need help.

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The other issue is that the signal from "in" to "out" is good and clear when just the two jacks are connected. It is still clear when the send is connected... but when I plug in the "return" jack, the signal becomes weaker, loses clarity, top end.

The signal is buffered on both sides (MXR analog chorus before the "in" and Ibanez echo shifter at "send" and "return" - both buffered pedals).

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Obviously this little switch I made is in need of a more nuanced approach. Can anybody please help me modify/redo my little circuit to make it work in the way I'd like?
 

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If you try and combine two different signal outputs to one input by directly connecting them, they conflict - fight each other, in simple terms. You need a mixer to combine audio signals.

That can be passive (but halving the volume) or active, keeping the same volume.

Also, a passive mixer will change level if you disconnect one input. The simplest version would be eg. two 10K resistors, one from each source output, connected to the same input.
Grounding the resistor when the signal is not connected would keep the level the same, but probably with a click as it changes over..
 
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