Audio mixing console

Anandhu's picture

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Joined: Jun 18, 2019

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Audio mixing console
June 18, 2019 - 2:10pm

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.

Aswinth Raj's picture

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Joined: Aug 16, 2016

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Audio Mixer 5 channel design
June 19, 2019 - 11:54am

Sounds like you are upto an intresting design. I do not have much XP into audio but I am still curious to know how this turns up.

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

I had a similar problem with gain being manipulated the problem was with the input impedance of the op-amp being low. Also since you are splitting the same audio signal for both Echo and summing I think its the same problem here as well. Try removing the Echo and check if the gain is constant. If then you can solve this probelm by adding a buffer circuit before the summer. 

Once you get this working you just have to duplicate the same for all five channel by providing five inputs to the summing amplifier.