I finished building a box of utility modules for my Arp2600M.
Iβve been working on this on and off since February.
I have to finish some calibration on some internal normalized routings and I may have to make a few fixes/mods if I find any new issue, but it seems to be working correctly after solving a few mistakes of mine.
I built 4 lfo (without any cv control) with square and saw-triangle-ramp (MS-20 style, so to speak), two DC-coupled 3 to 1 mixers, 4 vca, an adsr with gate delay in front of it and a bunch of cv utilities to control the pitch of the Arp2600M oscillators in a more flexible way.
I think I should spend a few words on the CV utilities. I took inspiration from a mod shown in a video by Anthony Marinelli: his 2600 has a bunch of switches to add/subtract an octave from each oscillator, plus switches for a custom interval controlled by a pot. So I took the voltage adder section from the YUSynth cv standards module and I built something similar in an external box. For each oscillator, I have a switch to add/subtract one octave, another switch to add/subtract a custom interval (slightly wider than one octave), a pot to add some external modulation (which I normalized to a triangle lfo going through a vcaβ¦), an indipendent pitch cv input and a switched cv input which can go to either A or B input or off.
The Arp2600M allows for paraphonic playing, it has two cv outputs which I connected to the A and B input. So, with a flip of a switch, I can decide whatever CV controls each oscillator pitch. Then, by flipping another switch, I can tune the oscillators up/down quickly (Iβm not a fan of the long coarse slider of the Arp2600). And I can add finally add vibrato, by patching the mod wheel output to the vca (which, by the way, I also normalled internally to the rising voltage of the gate delay, so I can choose for some modulation slowly fading in, if I donβt patch anything to the cv input βAβ of the first vca).
Iβm not super satisfied of the quality of the build, itβs messy inside (stripboard) and the external look is definitely cheap/home (especially the writing), but it does the jobβ¦
[edit: fixed some typing mistakes]
Last edited by sin night; 1 day ago at 12:26 AM..