Stop audio signal bleeding

Hi everyone, I have what I hope is a really easy question.

I am creating a blendable feedback loop circuit, which has 4 jack sockets (guitar in, send, return and out), and a pot between the return and send jacks so I can send the signal back to the send, creating a loop. This all works well. I also have a blend circuit, so that the dry input signal can be blended with the loop.

The problem is, as the signal goes from the return -> pot -> send, and the dry signal goes to send, some of the feedback signal is bleeding back down into the dry signal, and makes blending ineffective.

So what I am asking is this: how do I stop the signal bleeding. I was thinking I need to use a diode, I tried a 1N4001, and it didn't work at all, just made the signal horrible. I tried a zener diode I had lying around, and it had no audible effect, but didn't seem to stop the signal bleeding.

I have attached a very crude picture to help explain what I mean, where the ? is I think I need some kind of diode to only let the signal pass one way.

Any help is very greatly appreciated!

You need to show the circuit details to make the "bleeding" effect understandable. But apart from clarifying this point, I can tell you, that a diode won't work. The solution is either in adjusting the resistor network and potentiometer values, or adding a buffer amplifier.

OK, I'm using this as the feedback loop,



and adding in this blend circuit



does that help?

The basic problem is, that the blended feedback signal is shorted to the input. A series resistor (e.g. 1 to 10 k) isolating the input from the effect send node should help. Even inserting a buffer amplifier doesn't solve the problem without a series resistor.

I see, I had thought about a resistor, but I'm not sure how to add it, because ultimately the feedback signal and the input signal are connected via the send jack. Do I add the resistor between the two?

I'm under the impression, I clearly described where to place the resistor. It should replace the blue wire on the left.

I did think you meant there, but I was unsure as I was trying to work out the effect on the signal being sent to send. Wouldn't putting a resistor there effect the signal being sent to send as well as stopping the feedbacked signal blending into the circuit? I'm still pretty new to electronics and it overwhelms me a bit at times! Thank you for your help by the way

Wouldn't putting a resistor there effect the signal being sent to send as well as stopping the feedbacked signal blending into the circuit?

Click to expand...

It surely affects the original signal, at least causes some attenuation. That's the operation principle of a resistive blender. If the effect has no gain reserve at all (very unusual, I think), you need to add extra gain to circuit, not only a buffer as previously discussed. I think, rather than guessing about the result, you should simply try.