|
|
Post by mkjackn on Oct 27, 2021 20:40:41 GMT
Hello, Im trying to design a 4 channel audio mixer but am having some problems finding information about key bits. Using pots its possible to attenuate each input channel but how do I ensure the output sum is not bigger that 5v to avoid damaging other parts of the synth? Do I need to use an op amp buffer on each input or will the fact I'm running 4 signals into an op amp (mcp602) to mix them serve the same purpose? I know this is all a bit vague but my analogue electronics is not great an I'm having trouble adapting theoretical designs to the AE world.. Any help much appreciated!!  |
|
|
|
Post by robertlanger on Oct 28, 2021 8:28:17 GMT
I will give a basic schematic here later today!
|
|
|
|
Post by mkjackn on Oct 28, 2021 9:06:24 GMT
I will give a basic schematic here later today! Thanks Robert that would be amazing! |
|
|
|
Post by robertlanger on Oct 28, 2021 9:07:55 GMT
Here you find the core of the 4-4 MIXER module, showing the basic principles. R10/R11 make a virtual ground of 2.5 volts, which is also the "ground" for the pots; C4/R9 make the normalization of the audio sum to the virtual ground level, meaning the summed signal oscillates around the 2.5 volts level. For audio, the first opamp would be sufficient; the second one does only an aditional phase reverse (because the first one is also an inverting mixer) to keep the phase identical to the inputs (which does not an audible difference usually). HTH! ![]()  |
|
|
|
Post by mkjackn on Oct 28, 2021 9:45:32 GMT
Here you find the core of the 4-4 MIXER module, showing the basic principles. R10/R11 make a virtual ground of 2.5 volts, which is also the "ground" for the pots; C4/R9 make the normalization of the audio sum to the virtual ground level, meaning the summed signal oscillates around the 2.5 volts level. For audio, the first opamp would be sufficient; the second one does only an aditional phase reverse (because the first one is also an inverting mixer) to keep the phase identical to the inputs (which does not an audible difference usually). HTH! ![]() <button disabled="" class="c-attachment-insert--linked o-btn--sm">Attachment Deleted</button> Thanks Robert this has answered a lot of the questions that I had! |
|
|
|
Post by keurslagerkurt on Oct 29, 2021 13:53:06 GMT
Here you find the core of the 4-4 MIXER module, showing the basic principles. R10/R11 make a virtual ground of 2.5 volts, which is also the "ground" for the pots; C4/R9 make the normalization of the audio sum to the virtual ground level, meaning the summed signal oscillates around the 2.5 volts level. For audio, the first opamp would be sufficient; the second one does only an aditional phase reverse (because the first one is also an inverting mixer) to keep the phase identical to the inputs (which does not an audible difference usually). HTH! ![]() <button disabled="" class="c-attachment-insert--linked o-btn--sm">Attachment Deleted</button> Thanks for giving a glimpse in your modules! I was wondering if there are specific reasons for using the LMV358 as opamp? I always reside to the MCP60(0)2 in my AE designs. |
|
