Shocktave is crazy

[bdevlin]

Despite not getting voltage readings anywhere near where there are supposedly supposed to be, this circuit produces a great octave effect......with an odd catch.  It works GREAT on my Godin, less so on my ESP, and even less so on my Strat.  This of course HAS to be pickup related.  Even with a compressor before the Shocktave the Godin is by far the best.  I wonder if anyone could explain this.  The Godin has Seymour Duncan humbuckers, the ESP has passive EMG's, and the Strat has Lace Sensors.  If it was just a single coil issue I could understand.

Anyhow, I'd recommend this to anyone looking for a quick and easy way to get an octave down.  The schematic also lends itself nicely to straight perf board construction.

[Quackzed]

i built it and had some fun messing about with the input stage. in the end i came to the conclusion that this circuit has a sweet spot.
too little gain going into the flip flop section and you need to slam the notes to get the down octave and it dies out too fast, too much gain introduces too much treble and the flip flop will get confused ...
so, if your using active pickups and it sounds good, but your passive guitars - especially the single coils with their lower output-  are having trouble getting the octave down to lock in i would say
1. try to get more gain from the first stage by changing the collector resistor to a 5k ? or use a trimmer .. or just clip a 10k in parallel and see if that ups the gain
2. run a cap to ground .05  from the collector q2 to ground....
just looking at the schem i thing that will push it a bit harder and the smallish cap should cut some high end without stealing too much signal...helping the down octave 'lock in'.   try a distortion pedal in front of it... something with lots of sustain and low end.

[The Tone God]

On Forsaken, which is a design in a similar vain, I included a drive and buffer section driving the timer. The other thing that is nice is you can control the frequency of the timer which allows you to tune in the optimal frequency. All handy things.

Andrew

[Ben N]

OK, one of these days I WILL get to building one of these with a Vulcan input stage and a built-in LPF to smooth out the signal for a bit more predictability. I will, really.

[DDD]

I have to say that Shocktave circuitry is one of the most elegant and professional circuits I've seen as well as the other masterpieces by Joe Davisson.
Thanks, Mr. Davisson !