adding patch inputs for analog synths

[cockandswan]

Hey, I have a Korg Mono/Poly, Arp Odyssey and SH101 and I'm DYING to add some cv/modulation jacks to their various parameters.

Are there any resources on how to safely find the right place (maybe around the pot that controls the parameter) where i can add an input/output jack? (ie, outputs for oscillators, inputs for filters or modulating frequencies of oscillators)


Thanks,
Johnny

[expanoncolin]

Hey, I have a Korg Mono/Poly, Arp Odyssey and SH101 and I'm DYING to add some cv/modulation jacks to their various parameters.

Are there any resources on how to safely find the right place (maybe around the pot that controls the parameter) where i can add an input/output jack? (ie, outputs for oscillators, inputs for filters or modulating frequencies of oscillators)


Thanks,
Johnny

It depends on the circuit, really.  Pots that are set up as CV-generators have one side lug to V+, one side lug to ground (or V-), and the center lug to the CV in of the circuit.  A quick method would be to use a multimeter on continuity test mode to see if one side lug was connected to V+ and the other was connected to ground or V-.  In that case you could just use the center lug as the CV in - cut that wire and wire a switched mono jack so that the switched tip conductor is going to the pot center lug.  Just make sure you don't input too much.  Beyond that, there is always H11F3/Vactrols.  You could also find schems and work out what the pot was actually doing from there (variable resistance or CV source).

-Colin

[club_spouse]

im into this approach too.  My moog prodigy has some CV inputs and I think adding more would make it much more versatile.   

[cockandswan]

thanks a lot for the tip. that info about the pot is exactly what i was looking for.

i guess my follow ups would be along the lines of...

-what if i wanted to make my cv jack add/multiply to the cv already going to that signal instead of replace the original cv signal. would i just add a trim pot?

-is there a "go to" resistance i should use for limiting cv in this way?

-do you have any experience with the arp odyssey specifically? it has a dual phonic set up and i was hoping to tap into the gate/cv on each oscillator. i've had luck finding places where i can get at the cv of both, but the gating is a little over my head.

[expanoncolin]

thanks a lot for the tip. that info about the pot is exactly what i was looking for.

i guess my follow ups would be along the lines of...

-what if i wanted to make my cv jack add/multiply to the cv already going to that signal instead of replace the original cv signal. would i just add a trim pot?

-is there a "go to" resistance i should use for limiting cv in this way?

-do you have any experience with the arp odyssey specifically? it has a dual phonic set up and i was hoping to tap into the gate/cv on each oscillator. i've had luck finding places where i can get at the cv of both, but the gating is a little over my head.

If you have a CV, and you want to add it to another CV, you'll need to build a summing amplifier, something like this:



Sorry, not a lot of experience with the odyssey.

-Colin

[cockandswan]

that seems easy enough. maybe too easy... summing cv like this works well without powering the amp?

[expanoncolin]

that seems easy enough. maybe too easy... summing cv like this works well without powering the amp?

No no, you definitely need to power the amp, it's just not drawn there.

-Colin

[Jero]

Don't want to jack this so if there's a separate thread or anything...BUT

What about adding aud/vid outs on a keyboard? I have a toy I've been working on and thought it might be cool to hook it up to the tv/other. Seen it done before, but no one has explained themselves.

Anyways, like I said, don't want to threadjack (if someone would point me in the right direction), but your questions made me think of it.

[crochambeau]

Video operates on an entirely different bandwidth.

There are TVs that have been modified to allow audio signal to direct the electron guns, providing the standard waveform look. But that is a mod on the TV side, not the instrument side of the equation. Beyond that you're looking at a monitor with variable timebase (such as an oscilloscope) or actual video synthesis, of which I've seen mention in only a few places.

With a video synthesizer/processor you would likely pipe your audio range material in as a CV or modulation source. Again, this is a device that would be separate your keyboard/instrument.

I've seen the video subject come up a few times in the past few months at various places. This is something I would be highly interested in too, were I not dedicating my time to other projects..

[Jero]

http://www.youtube.com/user/frostedminipete#p/u/27/rKbeTfdUoDM

If you check out that video, that guy has his keyboard, from the looks out it plugged right into the audio/vid jacks. It's exactly what I want to achieve. I actually have the very same keyboard he's using, with diff bends/light mods.

If you're thinking, "Well why doesn't he ask that guy?"...well I have, and he apparently isn't interested in helping  haha

[crochambeau]

Have you tried simply plugging the audio output of your machine directly to an analog TV?

Avoid the TVs that blank out "bad" signals with a blue screen.

[Top Top]

If you get an old monitor, such as from a commodore 64 or other old computer, they take audio inputs well and don't go blue when they don't have an "acceptable" signal.

What you get mainly is bands of black in white that vary in their width according to frequency, and vary in smoothness/contrast according to waveform (ie: sine wave will get you a gradient-type band, and squarewave will get you solid black and white bars).