Rate and frequency control pedal

[peyton_c]

Is it possible to build a pedal that would control the rate and frequency of whatever signal you run through it without adding any other noise or changing the signal in any other way? Like an oscillator, but only for the signal that you run through it. I've been looking all over for something like this, but haven't found anything.

[GibsonGM]

Hi Peyton, welcome!

Can you describe what you want to do a little more thoroughly?   

"Rate" of what?    Change the frequency of what - the actual signal, like a "whammy pedal", or a 'variable octave pedal'?

That said, if you want to control OTHER effects with a pedal, that is not very hard to do...from the sounds of it, tho, you kind of want something is like a synth, but your guitar note is the 'building material' that the circuit could then warp?

[Mark Hammer]

I second the request for clarification.

[peyton_c]

Sorry, should have been more specific. Yes, it'd be a lot like rate and frequency control on an analog synth. The rate would be the rate of the oscillations, with lowest setting being slow and metronomic pulses and highest setting being a straight tone because the oscillations are too fast to perceive; and the frequency control would be a pitch shifter, with 12 o'clock being the natural pitch, counterclockwise lowering it, and clockwise raising it. I want something a lot like this: https://www.youtube.com/watch?v=hJUOhOlQL2k except instead of a synth-y drone, the signal of whatever instrument is being run through would be manipulated, with no noise at all if no notes are being played.

[robthequiet]

The oscillation is fairly straightforward, just search for "tremolo" in the above search box or even better in the ...

    DIYstompboxes.com »
    Schematics & Layouts »
    Schematics & Layouts »
    REQUESTS »
     Tremolo schematic

http://www.diystompboxes.com/smfforum/index.php?board=17.0

... section.



As far as the pitch shifting, given current technology, you would probably go with a digital/dsp approach, that would be my guess. If you want to transform the pitch of a live signal without reducing it to some kind of saw-wave drone sound, I would suggest starting with vocoder technology as an idea. In digital samplers, it is ridiculously easy to sample something and use a ribbon-type controller to play it faster or slower, although you are just replaying the wave without really shifting it. to have a digital stream and loop it at different rates is a more effective approach because recirculating a fragment goves the illusion of pitch shifting, though still probably "colored", if not distorted... Others here are probably more knowledgeable than I am regarding real-time shifting in dsp, so you may wish to pose the question again in the "schematic request" section or even the DSP http://www.diystompboxes.com/smfforum/index.php?board=19.0 section.

Here's a thread you might want to start with:

http://www.diystompboxes.com/smfforum/index.php?topic=23634.msg151198#msg151198

[peyton_c]

Well, if I use a tremolo effect, will I get the envelope that most tremolo effects have, where after each new attack, there is a slight decay? Because I'm looking for something more like this: https://www.youtube.com/watch?v=2zpCrUcZm-U As far as the pitch shift goes, couldn't I use the same technology that pitch shift/harmonizer pedals use? Like this: https://www.youtube.com/watch?v=tah66O2VesU

[mth5044]

How is your coding? The spin semi FV-1 might be the easiest way to get the pitch shifting done. The ability to do this in the analog realm is abismal.

[robthequiet]

As far as the pitch shift goes, couldn't I use the same technology that pitch shift/harmonizer pedals use?

Sure! But you are definitely looking at some DSP for that kind of result. The best analog vocoders will give you a similar clarity, but getting them to track pitch would be pretty tricky. Pretty sure you'll find a microprocessor of some kind in the better pitch-based effects.

... where after each new attack, there is a slight decay?

I don't see why you couldn't build a simple LFO with a square wave modulating the signal for a sharper "edge". There are probably guys on the forum who could figure that out in a matter of minutes (it would take me a day or two, tbh).

Sounds like you have two separate projects going here. The LFO would probably be easier to get done, but the pitch shift can be done, just a question of research.

[peyton_c]

Thanks a lot! I'm very new to building pedals, but this effect is very interesting to me, and I can't find anything like it that's already out there.

[antonis]

Just have in mind that, despite if they sound almost same, Tremolo & Vibrato are totally diferent effects...

Tremolo works with amplitude modulation (variable voltage gain) whereas Vibrato implements pitch modulation (fake frequency modulation - like Doppler effect in sound).

Βoth effects circuits have their own advantages (i.e. Trem is much more simple whilst Vibrato is more "sensational"..)

[slacker]

I'm still not sure exactly what you're after, the Electro Faustus thing is an oscillator providing the tone (frequency) and a square wave tremolo producing the on/off effect (Rate). Your guitar replaces the frequency part, the bit that make the actual sound, so you just need the rate part which is just a square wave tremolo. I'm not sure where pitch shifting comes into it, unless you want to mess with the pitch of the guitar with a knob.

The Fuzzrocious pedal just sounds like a deliberately badly designed tremolo that ticks, to give the oscillator sound, this is something you normally try and avoid.

[peyton_c]

I would not want the ticking, I was just showing an example of the square-wave tremolo as opposed to the typical sine-wave tremolo. I would indeed want to mess with the pitch of the guitar with a knob.