[sdiy] [AH] Custom ARP Avatar

[Pete Hartman]

On Sat, Mar 22, 2025 at 2:42 PM Michael E Caloroso via Synth-diy <
synth-diy at synth-diy.org> wrote:

> Cloning the ARP sequencer is pretty ambitious.  Already figured out how to
> expand it from 16 to 32 steps.  The challenge was how to replace the
> slideswitches for the busses with toggle switches.  Easiest solution was
> open-collector TTL logic configured as an OR gate, but those OC parts were
> hard to find.
>

Interesting.  John Daniels cloned the 1601 back when TTSH was all the rage,
kits for those are still available from Synthcube.  He simply used the
slide switches (some big honkin things) and it was a straight port I think
at roughly the same relative size (what was it, 78% of original?) as the
TTSH.

He also did a more limited clone of the ARP keyboard, with the problem
being that the old type of keybeds weren't very available.  Someone (maybe
John himself) came up with the idea of using relays with a more modern
keybed but that was prohibitive in cost, so there weren't too many.  I've
looked at the circuit a bit and think I have an idea to work around that
and drive with a Fatar keybed and a microcontroller/DAC but so far I
haven't been able to get my hands on one of the clones to verify if my
understanding is right.
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