Using AOUT in SEQ to control pot'ed gear?

August 6, 2004

I have a Vermona analog drum unit on which the parameter values are all set by pots. (http://vermona.com/en/produkte/drm/drm1.html)

I'd like to take some of them out and replace them with components I could control with the SEQ+AOUT.

Does that seem like a feasible thing? Is a transistor the right thing to use and is it as simple as that or will there need to be more supporting circuitry? What is the resolution of the AOUT? Is it 0V or +5V only or can it be anywhere between @ 5/128th increments or what?

(I'm a relative electronics newb but don't go easy on me; if you're generous enough to take the time to answer and I don't understand I'll go find a book.)

many thanks

August 6, 2004

I have a Vermona analog drum unit on which the parameter values are all set by pots. (http://vermona.com/en/produkte/drm/drm1.html)

I'd like to take some of them out and replace them with components I could control with the SEQ+AOUT.

Does that seem like a feasible thing? Is a transistor the right thing to use and is it as simple as that or will there need to be more supporting circuitry? What is the resolution of the AOUT? Is it 0V or +5V only or can it be anywhere between @ 5/128th increments or what?

(I'm a relative electronics newb but don't go easy on me; if you're generous enough to take the time to answer and I don't understand I'll go find a book.)

many thanks

chriss · August 6, 2004

I'd like to take some of them out and replace them with components I could control with the SEQ+AOUT.
Â
Does that seem like a feasible thing?

so far as i can see the vermona is not supporting cv inputs, only triggers but you need cv inputs to control what the pot is doing know. And this is not very easy. maybe you find someone whow did this allready with the vermona but i wouldnÂ´t experiment by myself. Its more than a transistor for sure.

What is the resolution of the AOUT? Is it 0V or +5V only or can it be anywhere between @ 5/128th increments or what?

The DAC has a resolution of 12bit and right at the moment the SEQ is supporting 7bit, that means you have 0 to 12 volt in 128 steps.

chriss

chriss · August 6, 2004

I'd like to take some of them out and replace them with components I could control with the SEQ+AOUT.
Â
Does that seem like a feasible thing?

so far as i can see the vermona is not supporting cv inputs, only triggers but you need cv inputs to control what the pot is doing know. And this is not very easy. maybe you find someone whow did this allready with the vermona but i wouldnÂ´t experiment by myself. Its more than a transistor for sure.

What is the resolution of the AOUT? Is it 0V or +5V only or can it be anywhere between @ 5/128th increments or what?

The DAC has a resolution of 12bit and right at the moment the SEQ is supporting 7bit, that means you have 0 to 12 volt in 128 steps.

chriss

moebius · August 6, 2004

Hi. Sounds interesting :)

You should get the schematics for your Vermona, as it might reveal control voltage insert points. Of course you can check function of the pots by measuring voltages (voltage diviner? variable resistor?)

Anyway there are several different schemes for replacing pot with something voltage (or data) controllable:

Yes, transistors will do sometimes . I don't remember the site, but it was 'bout adding velocity CV -> to PAiA Fatmans A(S)R.

FETs: http://graffiti.virgin.net/ljmayes.mal/comp/vcr.htm

Vactrol (or similar) optos - warning, kind of slow.

OTA's:

http://www.uni-bonn.de/~uzs159/ota3080.html

http://www.musicsynthesizer.com/DIY/Grant/OTA.html

ect.

Digitally controllable resistors: Source code for a modified AOUT driver already exist.

--- Yes, AOUT is capable of 12bit resolution, but MBSeq supports only 7bits, so it isn't optimal choise for doing this kind of thing..

Bye, Moebius

moebius · August 6, 2004