Why do delays pitch shift when delay time adjusted?

[AzzR]

Kinda curious on this one.

-Azza

[Mark Hammer]

Any time the sample out rate is different than the sample in rate, or the playback rate is different than the record rate, the pitch will shift accordingly.  It is no different for delays than it is for magnetic tape or vinyl disc.

[AzzR]

Thanks, I enjoy utilising this sound but never really knew why it happened.

-Azza

[sevenisthenumber]

is it the same as the squirrelly fast forwarding a tape sound? sorda....  maybe...

[Mark Hammer]

In fact, the first "Whammy" pedal (before Digitech made the Whammy pedal) used this very principle.

HISTORY LESSON ALERT!!
The old Electro-Harmonix "Hot foot" pedal ( http://filters.muziq.be/model/eh/hotfoot ) was a footpedal with a flexible shaft attached to it.  The free end of the flexible shaft could be attached to the shaft of a pot/control on an effect pedal.  As you moved the foot treadle on the Hotfoot back and forth, it would rotate the control on the effect pedal.

Because the Hotfoot had the flexible shaft coming out the side, parallel to the ground, when you attached the free end to a pot, there was so much torque on the shaft that the effect pedal had to be either very big and heavy, or attached to something.  If not, the pedal would flip right over from the shaft torque.  As well, the wing nut used to secure the free end of the flexible shaft to the pot (you had to remove the control knob from the pot first) was large enough that you could only use the Hotfoot when the pedal controls were spaced far enough apart.  Between the flipping over and the control spacing issue, there were few pedals you could easily use the Hotfoot with.  It was a very big foot pedal too, so I imagine not many sold.  EH eventually dropped that product from its catalog.  I had one, and liked it, but sold it somewhere around 1980.

More recently, Tone in Progress has released something called the Third Hand ( http://filters.muziq.be/model/tip/thirdhand ) which gets past the problems of the Hotfoot.  It is smaller and fits on a pedalboard more readily.  Plus, the flexible shaft comes out the top instead of the side which makes it more flexible than the original and more compatible with how controls are mounted on stompboxes.  It also attaches easily to pot shafts that are spaced more closely than the original could handle.

How was it used?  The application one would see in ads at the time was to control the delay time of a Memory Man pedal.  By playing and quickly changing the delay time with your foot, you could "bend" an entire chord, as well as individual notes.  Start with the delay time short and lengthen it with the Hotfoot, and your pitch would go down.  Start with the foot treadle pulled back for a long delay time and quickly push it forward, and your pitch would go up.  I tried that, and it was a lot of fun.  (My own principal use of it at the time was to control the output level of my compressor)

Digital pitch shifting pedals like the Digitech Whammy do a better job of this and also allow more control over the range of bend, but the Hotfoot/Memory Man combo came first.

Of course, if you know anything about the history of musician Les Paul, you will know that Les used variable tape speed to change the pitch of notes several decades before the Memory Man pedal was invented.  Then came David Seville and the Chipmunks (Alvin.  ALLLLL-vin, ALLLL-VINN!   What!!), and so many others.  All used the same basic principle: if the sped that something is sampled/recorded at is different than the speed/rate used to play it back, the pitch will change.

[petemoore]

Say you have a boat sitting still, but the waves are steady, and that means a frequency between peaks and troughs.
  Like a signal wave except an analogy.
  Now start the boat moving and hit the gas, point the boat into the wave direction...frequency rises.
  Hit the gas with the boat pointing the same direction the waves are moving and the peaks occur at a lower frequency.
  Very much like a tape with a recorded signal [a waveform recorded on it] and the playback head of an echo machine [like on Mike Battles Echoplex] picking up the signal...when the head is indexed [moved from the fixed position where the tape would go steadily across it] the frequency goes up or down.
  Tape heads can only move so far up or down the tape in respect to the record head position though, and boat could keep right on going.

[GREEN FUZ]

Say you have a boat sitting still, but the waves are steady, and that means a frequency between peaks and troughs.
  Like a signal wave except an analogy.
  Now start the boat moving and hit the gas, point the boat into the wave direction...frequency rises.

Oh I get it. Do you mean kind of like this?

[petemoore]

  More peaks [or anything else] in the same unit of time = higher frequency.