Octave Theory/Design Day

An octave pedal, as the name implies, is a circuit that’s meant to increase or decrease an audio source by a full octave. Unfortunately, these circuits are also often incredibly complicated.
However, I’ve had an idea for an octave-up schematic for some time now, and I just recently got the chance to test it out!

Here’s an explanation of how the circuit works:


The circuit gets divided into four sections, A through D.


Section A does some basic regulation to the waveform, first normalizing and then amplifying it, as shown above… Nothing too significant, just some basic preparation for the rest of the circuit.


The second stage uses two diodes to divide up the positive and negative peaks of the wave, and separates it into two channels.


Section C does two things- first, the negative peak band is inverted, meaning both waves are positive. You can see that the two hold (roughly) the same voltage.


After this, the waveforms are mixed together, and we can see we finally have 440 Hz, twice the Hertz value of our input- in other words, a full octave! This works due to the way that waveforms work- When the negative peaks are set to positive values, the amount of pulses (the frequency) is effectively doubled.


All that’s left is section D, which normalizes the waveform and shapes it to look (and sound) something like the input.

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This entry was posted in Circuit Crap, Effect Pedals, Music, Projects, Schematics. Bookmark the permalink.

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