Audio matrix mixer

I’d like to build a 4 in 4 out audio matrix mixer controllable by Arduino. The purpose is ‘no input’ style feedback generation using graphic eq guitar pedals patched between the outputs and inputs. I’d be using Maxuino to send attenuation ramps and routing commands from Max/MSP to the Arduino.

Any suggestions and/or pointers to potential challenges would be appreciated!

The mixer would:

— allow routing of any combination of outputs to any combination of inputs
— allow attenuation of the signals in the feedback paths

Possible ingredients:

Matrix routing: MAX4549 via SPI library
Attentuation: AD5206 via SPI library
Arduino Mega

If someone could look at the ingredients and let me know if I'm barking up any kind of reasonable tree I'd appreciate it!

I had an idea to do something similar before. My goal was to be able to swap guitar pedal order digitally.

I think you may have a good combination, however the max4549 is a triple 3x2 setup, which may be overkill depending on how many things you have hooked up. Converting the audio signal to digital before the crosspoint switch, and then back to analog afterwards sounds doable. I haven’t tried it though, as I abandoned my idea(my pedals decided they only liked a specific order).

I’d say one thing to be sure of is most chips won’t like a negative AC voltage, and a guitar (pedal) can sometimes have a swing > 0.3 to 0.3v. Just bias the signal to bring it into a positive area to work with. The datasheet for the max4549 says it has internal voltage dividers for a bias.

Your ADC/DAC combo has a different input and output quality, but both are more than enough to achieve good audio quality. Depending on the signal you are throwing through this, you may only require something much lower quality. Unless you can find the chip for cheap, and find a DIP version or can solder SMD chips well, reconsidering is also an option.

Some things to consider. Good luck!

p.s. you can type [ url ] (your url here) [ /url ] but without the spaces in the “” areas, to give a hyperlink to the webpage, or click the 2nd row, 3rd from the left button (under the underline button), rather than having to copy/paste to open it.

Arduino is not fast enough to do all that processing. If you kept it in the analog domain and just had it control analog switches, volume control, filters, you'd be okay.

Do you want a just routing matrix or you also want to mix your different input to do several mixes ?

Considering the 1st work, you only need to buy a router chip that get several input and allow them to route them on several output. Arduino can do it easely because it's just driver a chip. For the 2nd way, it's more simple to get an audio mixer you can drive with mide (like an 01V digital mixer).

Try looking for mm1631 IC to realize the 1st way, and ad8113or ad75019 for a more complex stuff !