[sdiy] Modding a Roland SH-201

[Scott Nordlund]

It's a very insane idea.  I'm not familiar with the SH-201, but odds are that the audio engine consists entirely of one or more DSPs and an audio codec (ADC and DAC).  You really can't do much of anything with this unless you want to basically re-engineer the whole thing from the ground up.  Paradiso's stuff works because the signals he's patching out can be found in the actual circuit.  On the SK-1, for example, each of the four voices comes out a different pin on the main IC.  They are then enveloped by signals that come out of different pins, mixed, lowpass filtered, and finally sent to the output.  If you were so inclined, you could make an output for each voice, where they can then be filtered, mixed, panned, etc. arbitrarily.  In the SH-201, these signals exist only as digital data that is passed between registers and multipliers and so forth within the DSP chip.  You can't patch this out any more than you can a desktop PC.  If you really wanted, you could probably reverse-engineer the firmware and turn it into an FM synth or reverb processor or whatever you want, but in that case you'd be better off just starting from scratch.  Or just buy something that does what you want it to do in the first place.

You could, however, patch out more or less any analog or "hybrid" polysynth to some degree.  I've even considered it, but I figure the process would be far too time consuming and expensive, and the result too esoteric (probably to the extent that it's less useful than the unmodified unit) to make it worthwhile.  On a small scale it can be an interesting idea, but completely patching something out is best left to simple monosynths or Casios. 

----------------------------------------
> From: taciturn_unquiet at hotmail.com
> To: synth-diy at dropmix.xs4all.nl
> Date: Mon, 6 Apr 2009 16:36:44 -0500
> Subject: [sdiy] Modding a Roland SH-201
>
>
> Hey all,
>
> This is a project that I'm probably going to work on when summer comes around. Anywho, I was wondering if there's any way of patching out an analog modeling synth such as the Roland SH-201 (since that's the one I have sitting at home). I was kind of inspired by Joe Paradiso's assimalation of a couple of Cassio keyboards... http://web.media.mit.edu/~joep/synth.html
>
> If this is just a very insane idea, someone please tell me now before I start dreaming too big again.
>
> -Ian Smith
>
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