is there any simple (clean) Low Octave Analog???

[richon]

is there any simple (clean) Low Octave Analog???

i've been searching, but the one thing i get is the BlueBox, which isn't clean (fuzz)

[jacobyjd]

Analog Octave down != simple OR clean.

There's really no way to make that happen. The only thing I could think of would be to use a blue box or slacktave and LPF the crap out of the octave down, then add a gain recovery stage to bring it back up to unity.

[MarcoMike]

what about stealing the OC down from circuits as the microsynthesizer, or Pearl OC3 (3?)... or ashdown suboctave.... this  last one is integrated in my amp and it is a very small and simple circuit board connected to the main pcb... I am sure there are schematics online, somewhere...

[Mark Hammer]

There are two generic approaches to analog generation of an octave down.  One is the approach used by the Blue Box, which uses a flip-flop to generate a square wave triggered by rising and falling edges that exceed a threshold.  The flip-flop can only be in one or another state, with no in-betweens.  That's a square-wave output.  It can certainly be filtered to smooth it out, but it starts out life as a square wave.

The other approach also uses the flip-flop to derive the "pitch" of the note, but does use the flip-flop's output directly.  Instead it uses the flip-flop indirectly to "gate" the original signal at half the frequency.  In other words, lets say I had a 100hz sine wave.  If I omitted every other cycle and replaced it with silence, you would hear half as many peaks per second, which is a lower frequency.  By gating the original audio input, the content that gets heard starts out clean, and doesn't get too nastied-up by the gating.  People describe this as being "smoother".  The gating, however, still introduces its own artifacts, so it could not be described as absolutely clean.  Still, since the flip-flop output is a constant amplitude, using the flip-flop to gate the original signal tends to preserve more of the dynamics of the original, which people will perceive as being cleaner.

[richon]

excelent

and is there an example or circuit of the second way to reach the "one octave down"

[Mark Hammer]

Yes, the Korg, Boss OC-2, Pearl, and many others.

[earthtonesaudio]

I suspect you could make a clean octave down digitally with less circuitry than the OC-2.

[aziltz]

I think the Boss OC-2 was the cleanest example of Analog Octave Down.  It drives a flipflop with a 1/2 frequency signal and uses that to invert the polarity of the input signal.  Meaning, the octave down is created using the harmonic content of the guitar.

I think.

[chicago_mike]

Where can I find the ashdown octave schematic?