Control the main volume using MIDI?

jaalmadakan · 2014-03-24T12:39:35.000Z

Hi there,

I have a bit of frequency overload problem in some of my liveset tracks, which could be easily resolved using a sidechain compressor… but I don’t use a computer and a RNC compressor will cost me 200€… I can"t use T8 as master track and using volume enveloppe trigs won’t be practical.

So I’m thinking about going DIY and using an ARDUINO with a MIDI shield to mimic a sidechain effect. The idea is that everytime my Machinedrum trigger a kickdrum, the Arduino detects it (via MIDI IN) and sends (via MIDI OUT) a command to temporarily reduce the volume of the Octatrack.

I’d like to avoid having to send CCs on various channels to change each track volume… I’d be basically modifying 8 parameters, MIDI is 31250bps… and we’re talking short transients here… Not ideal. I want to be able to directly modify the main volume.

I’ve looked in the manual but couldn’t find any clue about how to do it. Is there some CC or SYSEX that I can use to control the main out volume of the Octatrack directly?

The other option would be to mod my analog mixer using digipots… which would be fun but a heck of a wiring/soldering job… I’d rather not do that

the_dreammer · 2014-03-24T13:56:57.000Z

Wouldnt it be cheaper / easier to find a diy compressor with sidechaining on it??
atleast… that would have been my first guess…
then i googled it… and couldnt find any within 3 searches… (ok, some ssl clone which looked difficult to build)

closed thing to it was :
http://audio.kubarth.com/fredopto/index.html

Hope it helps

Geneoart · 2014-03-24T14:50:41.000Z

""jaalmadakan"":

Hi there,

I have a bit of frequency overload problem in some of my liveset tracks, which could be easily resolved using a sidechain compressor… but I don’t use a computer and a RNC compressor will cost me 200€… I can"t use T8 as master track and using volume enveloppe trigs won’t be practical.

So I’m thinking about going DIY and using an ARDUINO with a MIDI shield to mimic a sidechain effect. The idea is that everytime my Machinedrum trigger a kickdrum, the Arduino detects it (via MIDI IN) and sends (via MIDI OUT) a command to temporarily reduce the volume of the Octatrack.

I’d like to avoid having to send CCs on various channels to change each track volume… I’d be basically modifying 8 parameters, MIDI is 31250bps… and we’re talking short transients here… Not ideal. I want to be able to directly modify the main volume.

I’ve looked in the manual but couldn’t find any clue about how to do it. Is there some CC or SYSEX that I can use to control the main out volume of the Octatrack directly?

The other option would be to mod my analog mixer using digipots… which would be fun but a heck of a wiring/soldering job… I’d rather not do that

Do you think midi is fast enough to accomplish a sidechain effect? I don’t have that much faith in midi.

jaalmadakan · 2014-03-24T15:07:14.000Z

DIY compressors are an option… but despite years studying electronics and signal processing, I still suck at soldering and I’m afraid of the noise floor I’ll end up with if I touch an analog signal path…

MIDI runs at 31kbps and a CC message is 2 bytes, i.e. 32 bits… so it should take just about 1ms to transmit from the Arduino to the Octatrack (trig from the Machinedrum to the Arduino can be instantaneous). It should be fast enough I think… not sure but it deserves a try.

rhizome · 2014-03-24T18:35:44.000Z

this is surprisingly not possible. in fact none of the mixer menu params can be controlled via midi

jaalmadakan · 2014-03-24T21:13:27.000Z

Two hours in
https://soundcloud.com/surgape/testarduinocompme/s-I22Jf

It pumps! Now I just have to tweak the envelope time and see if sending CCs on multiple channels can be done while keeping a good. But I need a more MIDI cables so that’ll be for another day.

edit: now sidechaining two channels , no problem. Also using two knobs on the arduino to control the sidechain amount and release time, awesome.

Interesting finds: the OT does not like being sent high speed CC data (e.g. below 5ms). Like it really doesn’t like that AT ALL. Will stop doing any sound on the affected channels and I had to clear memory from the factory menu to get it back on its feet. Maybe I should stop before I ruin a 1500€ machine only weeks before my next gig…

jaalmadakan · 2014-05-15T21:48:37.000Z

If anyone is interested, here’s an article I wrote about this project: http://project1404.com/2014/05/arduino-midi-sidechain-ducking-box/

analogback · 2014-05-15T22:46:16.000Z

thats cool. id like to try this arduino thing with my ot snd mbase11… do you think arduino is capable of handling bagloads of midi data with low latency and multiple midi ports simultaneously?

jaalmadakan · 2014-05-16T06:19:42.000Z

It will I think, but it will not magically make the MIDI bus run faster than possible… that bus is slow by today’s standards.