Octaver Q

[R@bbiT]

Hi !  I need advice about some good Octave up pedal I could build. I need clean sound, and I don't know much about octaver models. Shematic can be complicated, I like complicated things!

Thank you very much!

[Mark Hammer]

Q1:  Octave UP or octave DOWN?  Big difference.  One is monophonic, the other isn't.

Q2:  What do you mean by "clean"?  There are few, if any, analog octave units that are "clean" other than by filtering out the fuzziness.

[petemoore]

I figure your'e looking for Octave Up.
 These can be relatively simple.
 Clean Octave up is another matter, GEO has a "Mu Doubler", uses Mosfets and reportedly produces clean Octave Up, I haven't tried it, it looks complicated   .
 Octave Down was more complicated, but I'm getting a nice Octave Down from the Shoctave Divider [Joe Davisson's], which was unveiled recently.

[Mark Hammer]

Now that I've actually read your post *thoroughly*, one possible strategy for obtaining a "clean" octave up is to filter the signal BEFORE it hits the rectifier and mix the octave up signal with a clean signal.

The reasoning is this.  The standard phase-splitter/rectifier circuit like you find in the Scrambler, Green Ringer, Foxx Tone Machine, Superfuzz, and Fender Blender (to name but a few), takes the whole signal, cranks it up, doubles it, runs it through a tone control (sometimes) and presents that at the output.  So what happens to all the harmonics present in the original?  Easy, they get doubled.  Somewhere behind all that crap is the doubled fundamental which we perceive as an octave up, but boy does it sound fuzzy.

If the doubling is largely confined to the fundamental (i.e., the pure frequency of the note) by filtering a lot of the harmonic content in the original, and we boost and double THAT and mix it in with the original signal, we should, in theory, have something that sounds more like the "clean" octave up so many ask for.

Is there a current paint-by-numbers circuit posted anywhere that does this?  Sadly, no.  That doesn't mean some brave and clever soul won't read this post and think of one, though.

[jmusser]

As Mark says, there are no clean up octaves, but there are those that don't have as much apparent distortion sound to them. I have built a load of them, and so far, the "cleanest sounding" with the most gain, has been Tim Escobedo's "Psychtar" used in the octave mode. Then, you have the extra Sitar portion of it to play with too. I believe it has very little apparent ring mod to it also. That's my two cents on the subject anyway.