diode distortion question

[kefestvog]

I have a general question about diode based distortion (and octave)pedals.  How do they work and what is the difference between using diodes to produce a distition effect or using them to produce an octave effect?  I think I have seen some things in my reading that talk about putting a doide series in the feedback loop (like a Tube Screamer, I think) or putting a diode series in the output path (like an Octavia, I think).  But I've also read at Fuzz Central that you can switch off one of the diodes in an Octavia to produce a fuzz effect, now I'm confused.  So would it be conceiveable to put a diode series in the feedback loop of say... a Fuzz Face?  How about in the output path of a Fuzz Face?  How about both?  What kind of sound would I expect to get if it would even work?  Since they're both using a diode does the gain hitting those diode determine whether you get distortion or octave?  Just wondering.

[davebungo]

The difference is quite simple.  Octave effects perform full wave rectification where the negative portion of the input signal is flipped to become positive providing the frequency doubling effect.  Distortion effects basically clip the upper and lower extremes of the input signal i.e. lop off the top and bottom.  Exactly how the top and bottom are clipped and whether or not it is symmetrical or not combined with tons of other factors dictates how it actually sounds.

[jmusser]

R.G.s "A musical Distortion Primer" is what you need. Go to GEO FAQs at the top of this page, if this link doesn't work. http://www.geofex.com/effxfaq/distn101.htm  That ought to clear up things for you, since he shows what is happening to the wave form.