Passive octave... Just a theoretical idea.

[ExpAnonColin]

OK, so we all know that a balanced (or ring) modulator does 2 things:
Outputs the sum of the X and Y inputs
Outputs the difference of the X and Y inputs.

So, let's do some math.  You input your guitar to both the X and the Y.  You hit an A.  Ouput frequency, sum=S Output frequency, difference=D
X=220hz
Y=220hz
S=X+Y
S=220+220
S=440
D=X-Y
D=220-220
D=0

So, you'd output 2 frequencies: 1 at 440 hertz (exactly perfectly one octave above your guitar signal... theoretically.) and the other at 0hz.  Obviously, we can't hear 0 hz, and at any give point where X-Y=D, D=0.  So, you just get a simple 1-octave-up pedal.
For two octaves, then, you'd have 3 ring mods:  First 2 double, then have their outputs go in the final X and Y.

Surely I'm wrong.

-Colin

[amz-fx]

No, you're not wrong....  if you input the same signal to both inputs of a balanced modulator then the output will be octave doubled.  This works great for a sine wave but less so for more complex signals in that all of the harmonics are doubled and you end up with a slightly synthetic speeded-up-tape kind of octave sound. However, if done properly it will have less distortion than the full-wave rectifier doublers that are quite common.

regards, Jack

[Paul Perry (Frostwave)]

Certainly, if you run the same signal into both sides of a balanced modulator you get a mix of harmonics, predominantly double the freq of the fundamental...one interesting thing that is often overlooked, is what happens to the envelope of the signal.
I think the envelope goes to a kind of a 'squared' function, not 'squared off', like in compressed, I mean like x times x. Which would be like an expander function.

[puretube]

(anonymous... : )we had this topic here a while ago (old forum).
the math is true concerning frequencies - not conc. volumes:
you`ll get  distortion nonetheless...




//www.puretube.com

[puretube]

right, Paul: you got to pull the square-root from the output;

...or keep one input on constant level....

)hi, live  from opposite side of the planet)