I've got a Behringer Model D clone, it has midi and CV in
Note/pitch and note on/off is via midi (no problem) it also has Gate/CV (detailed below)
I'd really like to be able to trigger the 2 env/contour gates and control the cutoff from Axoloti. I'm aware the 0-3.3v out on the 2 channel dac would give me limited control over the 0 to +5 V on the lfo/cutoff. what would be the best way to generate the 5v triggers? how about the -5 V to +5 V for the lfo speed?
im a novice with electronics, but can just about wield a soldering iron, I'm open to breadboarding something!
thanks for any help!
Dan
(full input section) Oscillator 1 Control voltage: 1 V per octave LFO Control voltage: -5 V to +5 V Cutoff frequency Control voltage: 0 to +5 V Loudness Control voltage: 0 to +5 V Filter contour Gate: +5 V input trigger Loudness contour Gate: +5 V input trigger
disclaimer: Im not an electrical engineer, rather software engineer with a soldering iron... which is probably a dangerous thing - so take everything I say, here or other threads, on electronics with a huge pinch of salt, and proceed at your own risk.
anyway....
if you search on the forum you'll find some ideas on many of these topics... i know I've been there. Ive listed below, some (not all), of the discussions I had, that i found useful, but there are lots more (search eurorack)
generally: for gates/triggers, Id assume a cheaper level converter would do the trick for others 0...5v I used a rail to rail op amp
if you need audio rate, then yeah your going to need to use the codec outputs... which you only have 2 of.. so worth considering if you can get away with GP outputs instead... perhaps the D will smooth anyway.
to take up to 5v, you will need a 5v supply - ideally from the D, but there is a 5v on the axo board.
for -5v/+5 your going to need a negative supply... on eurorack you would take from its supply, as there is not one on on axo board - fortunately, this was not a problem i needed to handle in my case... but means unfortunately, means i cant help you. ... probably easier if you stick with 0..5v on the lfo if possible.
note: i didn't try to get accurate CV voltage (e.g. for pitch) , if you need this... Im not sure if this has extra requirements on the opamp, and Id expect you need to needs some kind of 'mapping table' on the Axo side to get the 0..64 to accurately map to 1v /octave .
If CV control is your aim, the simplest and safest (not the cheapest) way is to buy a MIDI to C V converter and drive it from the Axo. There are MANY versions out there, from stand alone boxes like the Kenton Pro-Solo (I have 4 of them) to Eurorack modules like the Doepfer ones, that produce Gates, Pitch and Aux CV, Sync'd LFOs, MIDI Clock, start and reset gates and much more, to simple add-in modules like the MIDImplant that produce just the pitch CV and Gates. No damage to the Axo, no level conversions, no inputs or outputs taken away from the Axo. Worth every penny spent.
I used to have a Kenton Pro 2, worked great, not cheap though. I had though about using a USB>CV converter or a midi>cv, im open to doing it that way. (i've got an old beatstep which will give me at least 1 channel CV)
but, i was trying to find a way to incorporate the AXO into the behringer Model D without needing extra stuff -especially as theres quite a lot of expty space in the skiff the Behringer D comes in, and i;d considered mounting an Axo in there, permanent like
some of it is perhaps beyond my wonky soldering abilities, but I have a tame local tech that could be pressed into action,if needs be.
as mentioned below - using an external midi>cv or usb>cv is an option, and it'd have the benefit of allowing me to use it with ableton etc too.
i've been speaking to Rob @ midimuso who's open to modding his CV12 moog-spec cv interface to be more compatible with the behringer D, so that'd be the easiest route. but still ties up/in another piece of hardware, and i would really like to mount an axo in the model D.
There is no reason you can't get a PCB MIDI>CV converter (or more than one) and mount it inside the skiff. Also any MIDI>CV module mounted in the skiff can be wired internally to the MIDI out of the internally mounted AXO too. Units like the MIDImplant (http://www.midimplant.com) has two outs, is a little over an inch square, and not too expensive (~50 euros). It has been a while since I looked for boards like this but I'm sure there are many competitors in the same price range or less.
- so take everything I say, here or other threads, on electronics with a huge pinch of salt, and proceed at your own risk.