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Octave Glitching

Posted: Wed Jan 26, 2011 10:15 pm
by elbandito
Why do some octave pedals glitch out so badly, while some others don't? And why do some of the glitchy ones sound decent while the glitchiness of some others sounds horrible?

This is just idle curiosity... I really like using octave pedals and I was thinking about trying out some new ones.

Re: Octave Glitching

Posted: Wed Jan 26, 2011 10:34 pm
by Teej212
do you mean digital octaves like a whammy or an octave fuzz?

Re: Octave Glitching

Posted: Wed Jan 26, 2011 10:41 pm
by Scruffie
It's how they extract the fundamental of your guitar signal to give the purest sine wave (Guitar signal being anything but a sine) for the octave generator to process and then also the... engine, if you will that gives you your octave above or below.

Take the Deluxe Octave Multiplexer, Best Analog Fundamental Extractor ever, it damn near actually gets a proper sine wave out of a guitar signal, but that's about as far as you can go in Analog and that circuit is very complex and the issue that lies there is it tracking your guitar in real time.

In digital, it'll be the algorithm doing the work, Octaves are harder to producer than they seem and it has to track your signal and produce that new octave in real time so yeah, that's basically why.

If you want clean Octaves, always go digital, if you want grungey fun, go Analog, digital will always win though in this case for decent octave pedals.

Re: Octave Glitching

Posted: Wed Jan 26, 2011 11:52 pm
by McSpunckle
Also, some octave-down fuzzes (like the Blue Box) do the octave after the fuzz, and it's two of them. So they kind of glitch between harmonics, making 1-2 octave down glitches.

Octave-up fuzz is a different matter entirely.

Re: Octave Glitching

Posted: Thu Jan 27, 2011 2:52 am
by Jero
Good thread
I need more octave pedals my self

Re: Octave Glitching

Posted: Thu Jan 27, 2011 8:43 am
by eatyourguitar
I remember searching for the perfect octave down fuzz. Like the sound of me playing a bass but on my guitar. It doesnt exist imo. But the morpheus is digital and it does a really convincing clean octave down. You would actuly think its a bass if u close your eyes. From the youtube videos, the infanem sounds great for an analog octave down fuzz. Its just as much as the morpheus. The phantom octave i have cool but it doesnt always do octave down sounds. Depends on a lot of things to work but mostly sounds cheap and lofi. Almost like a bit crusher.

Re: Octave Glitching

Posted: Sat Jan 29, 2011 12:33 pm
by smallsnd/bigsnd
what scruffie said. it mostly comes down to the filtering before the octave generation portion of the circuit.
if you take a really basic octave down circuit, remove the pre octave filtering and add an adjustable low pass filter, you'll be able to adjust the glitchiness to some degree. less filtered = more glitchy as the octave generator sees harmonics and tries to create octaves based on those.

Re: Octave Glitching

Posted: Sat Jan 29, 2011 1:27 pm
by elbandito
Scruffs, I just saw your schematic of the DOM on FSB... did you end up actually building one?

Re: Octave Glitching

Posted: Sat Jan 29, 2011 1:36 pm
by Scruffie
elbandito wrote:Scruffs, I just saw your schematic of the DOM on FSB... did you end up actually building one?

It's on the list... and it's a big list... which has now been put on the backburner due to other... commitments.

So no I didn't, but I did see a demo on youtube which was kinda cool and I had started making a clone of the original PCB layout, the eventual plan being to convert it to not use those pesky CA3094 and slightly less pesky CA3080 but it was kinda the last pedal on the list after i'd done the Attack Decay & All the Percussion effects, which will all be waiting a couple of months now.