I'm trying to design a 5 channel audio mixing console. I'm using TL072 OPAMP as my preamp and IC PT2399 for the echo. How can I connect a single PT2399 to provide echo for all 5 channels? I need to control echo of each channel seperately. Currently the output of my preamp is fed to a tone control circuit (modified baxandall). and then then output of tone control part is fed to an opamp. I took this output and split it using 2 resistors, one is fed to the PT2399 via a POT and other I have given as an input to a summing amplifier (5532 OPAMP). The circuit is working (tested with 2 channels), but the problem is that output gain is not perfect, and when I adjust the echo POT, the gain is changing. Also I want to connect a POT for PAN adjustment (L/R), for stereo output. Please help me and thanks in advance.