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use in modular analog synth

PostPosted: Wed Aug 25, 2010 11:44 am
by robotfunk
Hi, I just discovered this project, WOW!

this thing just begs to be used inside a modular synth, so I have some questions:
-can it be modded to have +/- 5V audio signals? (that's the standard in most modular synths)
-can the pots be modded to have external control voltage input? (either +/- 5V or 0-8V)

Re: use in modular analog synth

PostPosted: Wed Aug 25, 2010 1:47 pm
by guest
it depends upon what its doing in the modular

right now the ins/outs are capacitively coupled
so they cant be used for DC control voltages
but the signals are DC coupled right up to the last stage
and are DC coupled right after the first input amplifier
so a tap could be taken off here
and a simple inverting amplifier with gain -2
would recenter them all around 0

this could be done with a daughter board
with a quad opamp package and 8 resistors

Re: use in modular analog synth

PostPosted: Wed Aug 25, 2010 1:49 pm
by guest
almost forgot the other half of your question

the 4 analog section knobs
would be difficult to make CV controllable
but the MOD1 knob just goes straight to an ADC line
so that could be replaced easily
and there are 8 ADC inputs
so it could take in a lot of CVs

Re: use in modular analog synth

PostPosted: Wed Aug 25, 2010 2:17 pm
by robotfunk
Thanks for the quick answer.

I'm not so much interested in processing CV with it (although that would be interesting) but mainly controlling the effects parameters with CVs.

perhaps Vactrols (light sensitive resistor with a LED in a lightproof housing) could be used to replace the pots (using switched jacks to switch between them)..

mmm mouth watering ...
do you know if there are steps/glitches etc when you move the control knobs very fast? that's a minor niggle in most existing modular fx units... if not than this begs for voltage control...

Re: use in modular analog synth

PostPosted: Wed Aug 25, 2010 3:31 pm
by guest
if you only want to do audio
on the ins/outs
then you can just plug it in
the capacitive coupling will take care of the voltage difference

the vactrols might work
although it might be difficult to get them to track for stereo

there are some slight glitches depending upon the function
although most are pretty good
the ADCs are oversampled 256 times and then deadbanded
so they can be very stable

Re: use in modular analog synth

PostPosted: Wed Sep 01, 2010 9:00 pm
by cliffman
funny, my second or third though after putting this together was

"Sure would be neat in a eurorack format"
I think it will work fine with the synth in current form, but for the future
might be interesting if you do a new board.

Re: use in modular analog synth

PostPosted: Wed Feb 08, 2012 5:07 pm
by FSK1138
as soon as i saw the repatcher i thought -eurorack-!!!

Re: use in modular analog synth

PostPosted: Wed Feb 08, 2012 6:31 pm
by guest
awesome!

and you also just reminded me
that we dont have a repatcher forum yet
we will fix this shortly

Re: use in modular analog synth

PostPosted: Thu Feb 09, 2012 12:19 am
by mcanulty
I just now made one, I'm looking forward to seeing the cases and things that people come up with!

Re: use in modular analog synth

PostPosted: Thu Feb 09, 2012 11:41 am
by schmidtc
It's neurotic I know, to make patch sheets for a modular, but here's the panel drawing for the microdec in 5U. It could use some fixes of course, but it's sufficient for me.

Image

If another file format is of use to anyone, I'm happy to pass it along.