i love my elektron stuff as polyrytmic machines, i love my modular as the same.
it would be great if the modular could communicate back :]
is there any way this can be accomplished?
It could be a problem 
Usually when you have digital converters they are ‘DC coupled,’ which is basically a high pass filter to get rid of very low frequencies. Otherwise you get a problem called DC bias where the low frequencies are too deep to be heard but they still use up the headroom, resulting in decreased volume for the audible portion.
Also, on incoming analog signals you would also want to guard the converters against voltages that were too high and could damage the digital chips. Usually digital circuits operate at 3.3 volts or 5 volts, but CV signals can go as high as 9 or 10 volts (I think that’s the max output from the A4).
The problem is that most CV signals are very low frequency because they’re sending control signals for musical purposes which are orders of magnitutde slower than audio frequencies, eg at 120bpm a string of 32nd note triggers is the same as an 8hz pulse wave, whereas A/D converters typically filter away anything under ~20hz to prevent the DC bias I mentioned above.
Now I haven’t tested this on the A4, and I don’t feel like hooking up a bunch of cables to do so, but here’s how you could check: plug the output of an FM oscillator or an LFO from your modular into the A4 input, and use it as an input to the FX - eg the reverb - with the FX high-pass filter fully open (ie set to zero). Start the osciallator at the highest frequency you can hear and measure the A4’s output on a meter or scope of some sort (eg in your computer), you should get a continuous wash of reverb as you’re feeding it a continuous tone. Now turn the oscillator frequency down slowly and keep an eye on the A4 output - chances are when you get down to 20 ro 30 hz the A4 ouput will fall to zero, which would mean the brickwall highpass filter in front of the A/D converter is stopping the modular output signal from ever reaching the effects.
If, on the other hand the A$ keeps responding when the oscillators goes into sub-bass territory and on towards 0 hz, then it could work as a CV converter, which would just require a simple envelope follower on the inputs, which requires very little DSP resources. But I wouldn’t get my hopes up.
I’ve been trying to find out if the a4 are dc coupled and I’m pretty sure they are. Overbridge. Is sorta like expert sleepers which requires dc coupled I/o.
OT but has anyone seen a screen shot of overbridge? It should be out next quarter so I’d have expected at least a screenshot or an update of some sort regarding it’s release - nothing since they announced it…
Any way to reverse the cv outs to be cv ins?
Btw thanks for the informative post anigbrowl
You’re welcome. I can’t see reversing the CV outs to ins. Theoretically it’s possible but you’d need to be a master hacker with ninja-like soldering skills and the ability to reverse engineer the operating system. If you had those abilities it would be an awful lot easier and faster to just build your own CV-MIDI converter and use that.