[sdiy] My new ESQ-1

[Rainer Buchty]

Tim,

>Just scored an ESQ-1 for $50 at a used music equipment store! Its only
>problem is that one ovtave of the keyboard is dead.

An octave or "just" a block of 8 keys? If it's nothing more or less 
mechanical, i.e. the keyboard itself, keyboard PCB, or diodes, the only 
remaining failure is the keyboard processor -- which seems to die quite 
often on the ESQ1.

>The MIDI in is just fine however, so the dead keyboard is not a
>terribly big problem. You know the sad thing? Looks to me like this
>unit STILL has the factory patches in it!

What OS version does it run? (Hold down REC and press MASTER.) The 
latest is OS3.5 which also contains factory presets, any prior OS 
requires you to load factory presets from tape or via MIDI.

>Anyway, it makes some great electronic / ambient sounds (not so hot at
>imitative, despite the fact that the factory sounds try to emphasize this).
>If anyone has links for good ESQ-1 info / mods / schemos or sounds, I'd
>appreciate it. 

Shameless self-advertising follows:
	http://www.buchty.net/ensoniq

Also includes customization for your ESQ1 OS such as including own 
"factory" presets, changing default settings etc.

>Also, I'm thinking that the ESQ's voice architecture might be worth
>studying/replicating with a couple of AVRs. A one-voice ESQ would be a nifty
>(and realizable) micro-based project. Or so I think. :)

See http://www.buchty.net/ensoniq/files/ics1261.pdf for sound chip 
details.

Each oscillator is basically a 24-bit phase accu with 16-bit 
incrementum plus some bit-shifting / bit-stencil circuitry for proper 
wave address selection. I doubt, that a single AVR is able to supply 
more than the 3 required oscillators per voice with the required ~38kHz 
(8MHz/(8*(24+2))) update rate per osc.

Rainer