I've been scanning the DIY pages re: building an octave pedal from scratch, but I haven't found any explanation as to theory of their function. I want to understand the theory so that I can modify the function to produce another interval. My desired result would be a harmonizer with the sole function of producing a blendable fifth. Is this even possible in the way an octaver functions?

Thanks

maybe it would be cheap/easier to buy a boss pitch shifter. they have blendable outputs afaik.

A friend of mine was doing this for a synthesis course last year, although i think he was coding it in assembler to be implemented on a PIC. doing it that way has something to do with dropping a certain number of the samples for different intervals i think.

I think diode rings (as used in ring modulators) are used in some octave pedals. There are a bunch of ring mod schematics around, i bet you could use one of those as a basis for generating the "harmony" note, and then find a way to blend it with the "root" note.

The boss pitch shifter probably makes the most sense from a time/money perspective, but isn't nearly as fun!

Lonesome Bulldog wrote:Is this even possible in the way an octaver functions?

Not really. Octave pedals generally work in 2 ways, wave multipliers (ring mod style) for octave up, and divide, down circuits. Most pitch shifters work digitally. Dopefer (a modular synth company) has an analog pitch shifting module, but I haven't the foggiest idea how it works.

Benny wrote:cheap/easier

Zoom 505 multi effect pedal. Cheap crap, but it does this for around 20 bucks.

hbc wrote:Dopefer (a modular synth company) has an analog pitch shifting module, but I haven't the foggiest idea how it works.

If you're talking about the frequency shifter (A126), it's not a pitch shifter, really. It creates an output that is different from the input by a fixed frequency. So if that frequency is plus 500Hz, for a 500Hz input you'd get a 1kHz output, but for 5kHz input, you'd get a 5.5kHz output. There's no way to set it to produce a constant musical interval, it's for creating harmonically unrelated notes which are useful for certain odd effects. As far as I know, there isn't a way of producing a realtime analogue pitch shifter.

matt_stevens wrote:The boss pitch shifter probably makes the most sense from a time/money perspective, but isn't nearly as fun!

Yes.

hbc wrote:

Benny wrote:cheap/easier

Zoom 505 multi effect pedal. Cheap crap, but it does this for around 20 bucks.

No.

tarandfeathers wrote:

hbc wrote:Dopefer (a modular synth company) has an analog pitch shifting module, but I haven't the foggiest idea how it works.

If you're talking about the frequency shifter (A126), it's not a pitch shifter, really. It creates an output that is different from the input by a fixed frequency. So if that frequency is plus 500Hz, for a 500Hz input you'd get a 1kHz output, but for 5kHz input, you'd get a 5.5kHz output. There's no way to set it to produce a constant musical interval, it's for creating harmonically unrelated notes which are useful for certain odd effects.

I checked Doepfer and they apparently stopped production on this.

hbc wrote:Octave pedals generally work in 2 ways, wave multipliers (ring mod style) for octave up, and divide, down circuits. Most pitch shifters work digitally.

tarandfeathers wrote:As far as I know, there isn't a way of producing a realtime analogue pitch shifter.

I was afraid of this.

I want that one function of the Whammy without all the others. So if pitch shifting is only possible by digital methods, they're probably too much of a pain in the ass to develop huh? Ah well, Digitech and Roland are always reading my brainwaves so I'm sure in about a year there'll be a "Power Chord Pedal" out there for the masses. Sigh.

Lonesome Bulldog wrote:No.

Yes.

Lonesome Bulldog wrote:I checked Doepfer and they apparently stopped production on this.

In stock here.

I think its possible, it just may be impractical. Digital pitch shifters just take samples and alter the playback sample rate. This is, in theory, possible with a bucket brigade type analog storage device. It would be a total pain in the ass, but it could be done. This is one of those things that just happens to be very well suited to digital circuits.

You would have to figure that an analog solution would be possible. If a pedal can double the frequency to produce an octave up or divide it in half for an octave down, then surely there must be a way to build a circuit that would produce three halves of the frequency for the fifth.