Simple 'True' Octaves Up?

Started by zpyder, February 03, 2007, 10:07:43 PM

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zpyder

Howdy.

A while back I built a "Guitar Synth" (http://www.geocities.com/worthekik/guitarsynth.html).  This circuit, as far as I can tell does not work as intended.  However, it makes a hell of a noise generator if you omit the input, and just use the 3 knobs to control the sound.  I've also been messing around with some oscillators, and have been both using an oscilloscope program to see, as well as running them through my practice amp to listen.  Anyways, I would also like to create some sound effects for a recording project I'm finishing up and so I was constructing a little console for myself to have all the knobs nearby.  I decided to try mixing both an oscillator and the guitar synth outputs together just with a couple resistors.  Works fine, and I'm able to hear both in my amp and control them seperately.  I do get an interesting modulation on the guitar synth circuit when changing the pitch on my oscillator (which is audio range ~20-20kHz).  Interesting, but the very cool part is when I set my oscillator near it's highest frequencies...  When the oscillator is running so fast that it is near inaudible, the resultant modulation on the guitar synth boils down to nearly one pitch.  The cool part is that now when I tweak with frequency knob on the guitar synth the resultant output is a highly musical pseudo-scale.  Instead of a smooth (or in the case of the guitar synth, rather unpredictable) frequency ramp, I get a stepped scale with distinct pitches and gaps in between!  Nifty enough, but here's what I REALLY want to do with it:

I'd like to run an instrument (guitar) through instead of the oscillator.  But I would need to raise my guitar's pitch to ~15k-20kHz to modulate the thing the way I want to.  This could lead to some fun experimentation.  One idea is to run a seperate LFO (perhaps pseudorandom?) that drives an LED/LDR combo in place of the frequency knob on the guitar synth.  If the LFO was adjusted properly and the guitar riff played was fitting, I may be able to get a very rough ring mod-style, but more musical, scale out of individual notes on the guitar.  Crazy idea perhaps, but I need to know:

Is there a simple way to raise the Hz of my guitar signal??  It seems that I would need somewhere in the rang of 4-6 octaves up.  At least a 20x increase in frequency.  I don't think a fuzzy/octave pedal will not do, I would need literal pitch shifting.

Though this might be a fun one if we could get some ideas together.

zpyder
www.mattrabe.com/ultraterrestrial Ultraterrestrial - Just doing our little part to make new rock go where it should have gone in the late-90's, instead of the bullshit you hear on the radio today.

petemoore

4-6 octaves, your best bet I think they'll say is digital, by the time you multiply the signal that many times I'd expect lots of harmonic hash.
  This circuit, as far as I can tell does not work as intended.
  It looks like there's an input, because of the switching, two jacks and a level pot on the output, what was the circuit intended to do ?
Convention creates following, following creates convention.

R.G.

QuoteIs there a simple way to raise the Hz of my guitar signal??  It seems that I would need somewhere in the rang of 4-6 octaves up.  At least a 20x increase in frequency.
There are simple ways. The simple ways are not good.

There are good ways. The good ways are not simple.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

g3rmanium

Quote from: zpyder on February 03, 2007, 10:07:43 PM
Is there a simple way to raise the Hz of my guitar signal??

Not sure if frequency shifters are simple, but you might want to look into them.
Call me Johann.

Mark Hammer

I have a scan on my site ( http://hammer.ampage.org ) of a chapter from a Ray Marston book on using 4046 PLL chips.  Give that a gander.