control voltage from the digital realm [no not midi to cv]

eric coleridge · Post by **eric coleridge** » Sun Jun 03, 2007 9:45 pm

I don't think this is the circuit I was refering to above, but here's something:

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

Also, if you do a google search for DIY synth, you'll find dozens of circuits for building Midi/cv interfaces. You wouldn't neccesarily need to have MIDI equipment--just a computer MIDI interface (which could also be built).

synthetic · Post by **synthetic** » Mon Jun 04, 2007 11:00 pm

When I worked at Alesis, some guys would short over the DC blocking capacitors on the inputs and outputs of the ADAT to control laser light shows. You might be able to make a similar mod to a sound card.

eric coleridge · Post by **eric coleridge** » Sat Jun 16, 2007 4:36 pm

Here is where you can find the parallel/printer port adapter. It allows you to use your PC's printer port as a source of 16(?) Control Voltages to control your Moogers, CV Synths, etc.:

http://www.cgs.synth.net/
Scroll down to and click on "Parallel Port adapter for IBM PCs"

ColorForm2113 · Post by **ColorForm2113** » Sat Jun 16, 2007 10:57 pm

wow! i have to say this is one of the most interesting posts ive i think ive ever read. it makes me wish i knew more about computers. this is a really good idea, but my only concern is you would have perfect sequences set on your computer but the analog circuits themselves... dont they have a tendency to change slightly over time which would through off your sequences. if you can get your idea to work though, that would be brilliant

nicholas d. kent · Post by **nicholas d. kent** » Mon Jun 18, 2007 4:19 am

There's a PSIM oriented list here -
http://launch.groups.yahoo.com/group/Co ... ageSources

I guess it was being sold when I had no money and then when I did I heard later on the wait time was getting unreasonable and then it was discontinued.

Another tactic is to process the audio from a soundcard into a CV. For instance there are quite a few envelope followers that output CV. The Moogerfooger Low Pass Filter pedal for instance.

One can also patch most voltage controlled envelope generators into functioning envelope followers, but many modular builders stick to envelopes with only manually adjustable times and levels, you need the kind with CV inputs.

You could also turn frequency back into CV but there aren't many readymade projects or DIY schematics. Analogue Systems seems to be the only company building a module that does pitch to voltage at present.

matt the fiddler · Post by **matt the fiddler** » Mon Jun 25, 2007 7:57 am

synthetic,

if i were to short the caps, do you think that any pro audio programs would be able to read and then play back the current? IE, if I record some LFO from my modular

I know many audio cards have a range of frequency that they pick up- some worse than the elderly ear, the high end is usually limited due to sampling rate and shortcomings of the hardware, is the low cut off only due to the Caps in place or from a unintended hardware shortcoming? and therefore that easy to record DC and lower than 50 Hz signals?

synthetic · Post by **synthetic** » Mon Jun 25, 2007 8:34 am

The caps are designed to roll off the low end. I would experiment with a USB or Firewire interface, so if I blew something up it was the interface and not my motherboard. I don't see why any pro audio problem would have trouble playing DC. Make sure to choose an interface that has enough DC swing for you -- a -10dBu interface wouldn't have as much voltage swing as a +4dBV interface.

matt the fiddler · Post by **matt the fiddler** » Mon Jun 25, 2007 11:08 am

I found this, but the article costs $32 to read yuck.

hmmm

matt the fiddler · Post by **matt the fiddler** » Mon Jun 25, 2007 4:43 pm

http://www.springerlink.com/content/q878668tmhg333h1/

synthetic · Post by **synthetic** » Mon Jun 25, 2007 5:01 pm

I talked to an engineer who said that the resolution on the output might not be that great, not good enough for pitch for example. Audio D/As sometimes have DC offset and ripple, which is not a big deal since you have those DC blocking caps on the output. He suggested to just buy a MIDI/CV converter, which might not cost much more than the audio interface you might sacrifice.

This one has 6 CV outs, a 16-bit CV pitch out, and two built-in LFOs for $499. An audio interface with 8 outputs would be similar money. Maybe you should just eBay your interface and get something like this.

http://www.analoguehaven.com/kenton/pro2000mkii/

matt the fiddler · Post by **matt the fiddler** » Tue Jun 26, 2007 9:05 am

Well, it comes down to that it is still using the language of midi, which is not that good of a transfer medium for synth/ my purposes.- resolution problems, etc. There are some good aspects of midi, and I use it a lot for composition, etc

I may just have to be patient or see if i can design a DAC circuit some day..

I do have a midi to cv [.coms Q104] with 4 CV outs and would likely get the dopfer if i needed tons. [$800]

my dream module would be one that connected to interfaces like arturia's and other of the user programmable modular synth programs and could patch anything else you wanted from anywhere in the chain. Computers may be lacking in tone, but being able to put all of your envelope controls digitally, triggered by CV but outputting CV as well has some strong potential to seriously improve on what our synths/ foogers can do.

reset · Post by **reset** » Fri Jul 06, 2007 2:32 pm

How about this?

http://www.electro-music.com/forum/view ... hp?t=12266

You could get a Micro Modular and perform the mod mentioned in thread. That way you would have the Arturia-like SW interface.

Tibbon · Post by **Tibbon** » Sat Jul 07, 2007 10:02 pm

Some sound cards (and mixers, and other things likely) will have output shielding capacitors to block DC-Offset and other nasties (if i remember right). Unfortunately what this means is that DC-like signals (like really slow LFOs) likely won't pass.

Midi-CV conversion is probably the best thing I can think of still. Most computer voltages (serial and paralell) connections are standard things like +5VDC or whatever and don't change all that much. Won't be all that useful.

I suppose you could design a USB->CV that device that would run a proprietary input or whatever that wouldn't have to be midi, and avoid stairstepping or other midi based issues with higher resolution.

jamirokid · Post by **jamirokid** » Mon Aug 20, 2007 12:37 pm

What would the resolution have to be to make a smooth output? It would have to be pretty precise considering you're trying to one up a midi-cv conversion. The kenton is 16 bit, would it have to be higher than that?
Josh

matt the fiddler · Post by **matt the fiddler** » Sat Sep 01, 2007 12:10 pm

Well, I may just need to break down and get the Encore Expressionist.

http://www.encoreelectronics.com/cont_expres.html

8 channels of CV outs [enough to trigger drum modules, etc.]

A channel consists of a 1/4" control voltage jack, and a 1/4" trigger jack.

Each channel has
available pitch bend,
four modulations,
four LFOs,
six octave transpose,
two types of portamento,
voltage offset and tracking, and
trigger polarity.

The trigger jacks can be programmed to be a Positive Gate for triggering synthesizers such as Roland, ARP, and Oberheim. The triggers can also be programmed as S-Triggers for Moog synthesizers.

$600.00 for that.....

I can easily multitrack midi in finale and have 8 staves, one for each channel for even modifications.