DC-Coupled Control Voltage?

The Moog Forum Minimoog Forum
1

This is the first time I’ve read anything about DC-Coupled control voltage:

http://acapella.harmony-central.com/showthread.php?p=32265274

I was wondering if my E-MU 1616M Microdock box could produce the same cv triggering as the MOTU in this video:

http://www.youtube.com/watch?v=xFkkl_u7pmo

Here’s my emu specs:

Analog Line Inputs -

Type: servo-balanced, DC-coupled, low-noise input circuitry
A/D converter: AK5394A
Level (software selectable):

  • Professional: +4dBu nominal, 20dBu max (balanced)
  • Consumer: -10dBV nominal, 6dBV max (unbalanced)
    Frequency Response (20Hz-20kHz): +0.0/-.03dB
    Dynamic Range (1kHz, A-weighted): 120dB
    Signal-to-Noise Ratio (A-weighted): 120dB
    THD+N (1kHz at -1dBFS): -110dB (.0003%)
    Stereo Crosstalk (1kHz at -1dBFS): < -120dB Analog Line Outputs

Analog Line Outputs -

Type: balanced, AC-coupled, 2-pole low-pass differential filter
D/A converter: CS4398
Level (software selectable):

  • Professional: +4dBu nominal, 20dBu max (balanced)
  • Consumer: -10dBV nominal, 6dBV max (unbalanced)
    Frequency Response (20Hz - 20kHz): 0.0/-.06dB
    Dynamic Range (1kHz, A-weighted): 120dB
    Signal-to-Noise Ratio (A-weighted): 120dB
    THD+N (1kHz at -1dBFS): -105dB (.0006%)
    Stereo Crosstalk (1kHz at -1dBFS): < -115dB

E-MU 1616M Specs

I see my Microdock has DC-Coupling Inputs, but only AC-Coupling outputs. Would AC-Coupling control voltage work too?

2

AC coupled means it doesn’t go to 0hz (DC) The specs show that the lowest output freq is 20hz. That is a pretty fast control voltage oscillation.
But even audio frequency can be (and often is) used as a CV. The inputs being DC coupled means you won’t hurt them with DC signals. (Provided the voltage isn’t higher than the input can handle.)
One more thing to add. Those outputs are probably line level. or about .125 to .250 Vmax. CV’s are usually 0 to 5/20VDC depending on system.

3

Yeah, I just got more info that it won’t work :frowning:

Looks like I’ll have to buy at least a used MOTU box to use Reason for cv sequencing.

4

If you’re handy with a soldering iron you could always try a MIDIbox:

http://www.ucapps.de/midibox_cv.html

It’s a DIY 8 channel MIDI-CV converter @ 12-bit resolution. To generate CV you just have to output a CC or NRPN from your DAW and you’re there!

5

That’s something else I’m interested in, but not what I’m after in this case.

I want to use Reason to control the Voyager, but since it has no MIDI output the only way to use it that way is through it’s cv output, like in the video.

6

So do you mean I could send my drum machines audio output into one of the Voyagers cv inputs and make stuff happen without damaging anything?

7

You won’t hurt anything as the output of the at drum machine is line level and therefore around 1/4 to 1/2 volt. You can use a module like the Q118 from dotcom to bring the voltage up to useable levels.
What I meant in the original post is that audio frequency from the oscillators is very often used as a modulation source. There is no reason you couldn’t amplify the signal from your drum machine and use it as a CV. This would give you precise timing and control. I’ve experimented with using a mic and amp to provide signals to my old 2600. Some very strange effects were made using FM instead of a keyboard to control oscillators and the envelope follower to run the filter.

8

Some great information, thanks.