[sdiy] Help from the brain trust: Keyboard ideas

Elby Designs elby_designs at ozemail.com.au
Tue Jun 14 09:40:30 CEST 2011

I have a similar scenario (I think) with an ARP Odyssey where I am replacing
the ARP keyboard with a MIDI keyboard. As the ARP generates 2 voltages for
the duo-phonic action as well as a GATE and a TRIGGER, I am simply writing
software for my MIDI-CV to generate similar outputs. This way ANY MIDI
controller will work. The idea is to use 2 MIDI Channels, one for each VCO. 

The ARP actually generates a master keyboard voltage which is fed to both
VCOs and then when a 2nd key is pressed it generates a `difference voltage'
which is applied to VCO2 to generate the 2nd note. Relatively easily to
implement in code once you have established the voltage relationships
required.... :)

Best Regards
Laurie Biddulph
Mobile: 0400 257 645
Web: www.elby-designs.com

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of David
Sent: Tuesday, 14 June 2011 4:48 PM
To: 'Synth DIY'
Subject: [sdiy] Help from the brain trust: Keyboard ideas

There are a lot of solutions to get a CV out of a modern keyboard and I have
a MIDI-2-CV converter and a .COM keyboard controller which directly outputs
a CV, gate, trigger, and velocity.

My dilemma is a bit different. I'm trying to finish my Synthasystem and the
last thing I want to finish is the duo-phonic keyboard Nyle designed. I need
a keybed which mimics an old Pratt-Read keybed.

I had three ideas:
1. Hack a Fatar keybed and hook into the switches.
2. Use some Doepfer electronics which eventually output a TTL level voltage
at each key press and use the voltage to operate a small solid state relay
connected to each key.
3. Hack a Fatar keybed and replace the switches with micro switches.

I know it is a bit odd to move backwards, but the duophonic electronics are
built around a resistor ladder and a bus type keybed and I'd love to put
this last piece of the puzzle in. I'd like a solution which doesn't require
trying to find an old bus keybed with all their problems. I'd rather use a
modern matrixed keybed.

I've hit a wall with this and would love some divergent thinking.

Thanks in advance.


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