Aries Archive [sdiy] how to build a cv keyboard

[phillip m gallo]

Sakke, Cynthia,

The beauty of the world of synth is that everything is ok, everyone is
"right" (at least against personal criteria).  I for one, however, would shy
away from advising someone to build a analog keyboard (unless it was an
educational exercise) .  That is not to say i wouldn't recommend a keyboard
that emitted control voltage(s) (&Trig&Gate).  But a digitally scanned
keyboard is just as easy to construct (micro or no micro) and has sincere
advantage in terms of stability, and how the voices perform.  My late '70's
duo-phonic keyboard was interesting and capable of lot's on neat and new
capabilities.  But the Sample and Hold (using polystyrene cap, guard rings,
and charge injection compensation) never provided the stability, flexibility
and generality that digitally scanned keyboards have.

Also MIDI keyboards are easy and "cheap" if you value your time.  They do,
of course, imply a MIDI2CV interface but they too provide interesting
functionality above what an analog keyboard provides.

My first digital keyboard was a "parallel computer N-key rollover" circuit
ported to my key manual and feeding an 8 bit DAC.  This simple keyboard out
performed any analog circuit designs (for stability) i used at the time
(ARIES, CFR, ENotes, ARP).  But then again the key manual was very cool
(fishing weights used as "throw-bars" to provide a feeling of "escapement".
I also built non micro key scanners which fed 4 8 bit DACs for 4 voices
allocated by "first found" keypress.

Micro based key scanners allow "rule based" key allocation. MIDI keyboards
allow the "voice allocation" to occur some where other than the keyboard for
additional flexibility.

just some thoughts.

regards,
p

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