Tonefiend Forum

Ok here's what I thinking about for this circuit.

You said that it doesn't work well live. That may be the result of having almost no dynamic range. Play soft, it's as loud as if you play loud. So it might be interesting to add circuitry to bring back some dynamics.

Also this circuit would lend itself well to making an octave divider based on a CMOS counter like the CD4029. If you put a low pass filter on the octave divider section you could still get thunderous lows but keep the upper frequencies coming from the rectifier. Otherwise the octave divider itself will generate a lot of high frequencies as a result of its fast switching. Something to experiment with if you have the inclination.

Craig Anderton's book has an octave divider schematic, which also put some dynamic processing (mostly to attenuate the decay section so you didn't hear the octave divider sputtering as it shuts off). I went a-looking for the "Rocktave" schematic, and Craig must have had his lawyers follow up on it, because the one link that all other links point to is now gone! 8^(

Craig Anderton's octave divider (as I recall) just used a digital counter chip with some sort of front end on it. If what you feed into the counter is a reasonably-square wave version of the string's fundamental, then the counter will give you a "divide by two" (one octave down) and "divide by four" (two octaves down) output signal (that will definitely be "square" as they are coming from a digital circuit)!

Now I don't think I've ever seen a "divide by 3" octave divider. That would give you some strange interval, let's see if I can compute it here...

Supposing you start with good old 440 Hz which is A. Divide that by 3... 146.7 Hz. That comes out to just about a "D". I think that's a perfect 4th? 2 octaves down? That's worth investigating, if for no other reason to avoid it forever!

Check this video for some of the "sweet, lush" (cough) sounds on tap from the Paia Rocktave which is Anderton's design!

To bring back dynamics, you'll need an envelope follower on the input, then a voltage controlled gain stage at the end that re-imprints the input's dynamics onto your output. I don't see any examples of this after casual searching, so I might even try to design one.

Wow. I dig the howling, square wavey sound that the octave divider put out. Some of the notes became more flatulent sounding, so I'll have to figure out a way to minimize that. Combined with the modified Fender Blender octave up, it could do some really cool synth sounds. Does anybody besides myself and Digital-Larry have any ideas? I'm really excited about where we're going with this, but I'm interested in other opinions.

WOW! Take that Zachary Vex! The tones in that video are truly unsane!