From donstavely@msn.com Thu Dec 13 09:20:03 2012
Subject:Re: Korg CX-3 analog vs digital?

I use 91 individual 3rd-order Sallen-Key peaking filters, each tuned to their respective notes. Painful, but the result is very pure sine waves. 12 notes times 8 octaves needs 24 quad op amps, and a ton of R's and C's. I handle leakage with some injected crosstalk between filters four octaves apart.

Hammond waveforms look and sound pretty pure to me, but there may be a little second harmonic in the lower couple of octaves. I can easily mix a little in if it is important to the sound.

I switch the 91 tones to the 9 drawbars using 138 quad analog switches. The interconnect handles foldback correctly. I can "bounce" the key signals to the switches to get faithful key click.

Percussion is easy to replicate, with the proper envelope gating the 2nd and 3rd harmonic drawbars.

My chorus/vibrato is a true analog 25-stage L-C delay line, scanned electronically to emulate the Hammond electromechanical scanner. I have some tuning to do, but the breadboard sounds pretty damn good to me.

To stay true to the analog promise, I considered doing a Dynacord CLS-222 ripoff. But everybody is gaga over the Ventilator, so I my not even try an analog Leslie emulation. I hate to concede to digital but I have already bit off more than I can chew.

Don