[sdiy] Hammond Aurora Keybeds

[brianw]

Several replies have recommended a scanned solution, with either a processor or discrete logic.

I wanted to point out one major difference: A pure analog V/oct ladder only works monophonically, you cannot get multiple voltages out of it. There are some designs that can manage 2 outputs - lowest key and highest key - but that's still rather limited.

A scanned keyboard is compatible with monophonic, duophonic, and polyphonic - even if you don't have the resources for note-per-key voice circuitry.

For that reason alone, I would recommend a digital, scanned keyboard solution. You can use the processor to implement one or more voice assignment algorithms to feed multiple CV+Gate outputs.

I agree with you that a note-per-key synth might be too much work, so choosing a solution that maintains polyphony would be the second best choice.

Brian

p.s. There are some kits that you could connect to this keyboard, but I've found them to be implemented strangely (at least compared to my expectations). I found it easier to just create my own firmware (whether MIDI output or CV output or both).


On May 14, 2025, at 7:51 PM, drheqx wrote:
> Hi all,
> 
> I have the keybeds and draw bars etc. from a Hammond Aurora organ. 
> 
> These are not matrix type keybeds. Each key closes a switch to a common bus. 
> 
> Is this a good time for me to consider doing a volt
> /octave keyboard controller? 
> 
> I definitely don't want to midify these. That would be a waste.   I was considering building a voice per key synth because i love these key beds and it would be so unique, but I'm short on time like so many of us. 
> 
> Anyone know of a good kit to make a 1v/ oct controller, maybe with some added features.