Pitch shifting

[Processaurus]

Here's a neat write up that Dirk Hendrik did, who followed through on these ideas about making a working BBD harmonizer, very impressive, and honest, too, about the limitations and shortcomings of that approach.  Unfortunately it looks like the picture links are dead, lots of scope shots.

http://www.diystompboxes.com/smfforum/index.php?topic=35335.0

As a musician I'm really excited about how my new-ish ehx HOG harmonizer works, kind of a general purpose granular synthesizer for guitar, though the tinkerer inside is a bit chagrined...

[DavidRavenMoon]

Read p11, where Anderton notes that the pedal uses 42 (yes forty-two) chips in all.  

So, are you up for some serious kluging?

So does this mean that the question of life, the universe and everything was, "How many chips are required to make an analog pitch shifter?"

Yes, and thanks for all the fish!

[~arph]

I've seen D_H's approach, really impressive indeed, but it's a completely different route as the one I'm trying to explore.

my attempts are mostly harmless...

[DougH]

I get enough pitch shifting and harmonizing between my HOG and my Super Shifter. The HOG is pricey but the SS is pretty cheap, $150 or so. Those 2 units alone could keep me busy for decades just operating them. But if building an analog pitchshifter is your idea of fun- go for it.

[slacker]

I could start out  with something like a Echo base or even a rebote and change/add a saw lfo.

If I've understood you correctly I don't think you'll be able to do this with a PT2399 based delay. The minumum delay time is about 20-30ms so you couldn't modulate it at 50kHz. A sawtooth wave a "normal" LFO frequencies would probably be interesting though.

[~arph]

You're right, that is about the minimum time for a PT2399. But I think that doesn't really matter if I modulate above this minimum delay time (which is when you put pin 6 to ground) In order to be able to change the pitch I think all I have to do is modulate at a lower frequency than the lowest interternal clock value which is 2Mhz, so I'm safe here. The pitch shift is not determined by the actual delay times, but the speed of change in delay time, though keeping delay time as low as possible is the best as you want the quickest response you can get).
This is still all just theoretical and I will test this as soon as I finished redecorating my bathroom.

[MikeH]

Unless you are one of those folks who prefers to go up Mt. Everest on the difficult side, and has no social life or need to actually take time to play music, there is really no reason to attempt an analog harmonizer/pitch-shifter.

I almost shot an entire bite of pear through my nose when I read this.

[Mark Hammer]

When I was 8, I had my tonsils removed, as was the custom of the day.  I was, as they described it to me then, "a bleeder".  To stop the bleeding, some sort of "thing" was installed that had a length of string inserted into my nostril, down into my throat and out my mouth, where the two loose ends were tied together.  The string, or tubing, or whatever it was (that was a looooooong time ago, remember, and I was drugged up) was used to hold a pad of some kind in place in the middle of my head, to absorb the blood.  When it was time to leave the hospital, someone came and snipped the string/tube, and gave a yank at one end.  I watched this knot disappear into my nose, felt like my brain was being re-arranged for a few milliseconds, and then to my utter disbelief this huge red clotted snotty lump came flying out my mouth.  It was like someone had caught a fish in the middle of my head and was yanking it into the boat.

It may have been going the other way, and may not have been a chunk of pear, but I imagine the experience would be quite similar to snorting a pear chunk out one's nasal passages.  I do not recommend it.  Still, glad to have brought a smile to your day.

[~arph]

When I was 8, I had my tonsils removed, as was the custom of the day.  I was, as they described it to me then, "a bleeder".  To stop the bleeding, some sort of "thing" was installed that had a length of string inserted into my nostril, down into my throat and out my mouth, where the two loose ends were tied together.  The string, or tubing, or whatever it was (that was a looooooong time ago, remember, and I was drugged up) was used to hold a pad of some kind in place in the middle of my head, to absorb the blood.  When it was time to leave the hospital, someone came and snipped the string/tube, and gave a yank at one end.  I watched this knot disappear into my nose, felt like my brain was being re-arranged for a few milliseconds, and then to my utter disbelief this huge red clotted snotty lump came flying out my mouth.  It was like someone had caught a fish in the middle of my head and was yanking it into the boat.

Oh lord..it's amazing where this thread goes

[Mark Hammer]

Oh hell, I only build stuff so I can tell stories!

[scratch]

For reference the the Spin Semi FV-1 (Small Bear carries them) datasheet shows two programs with 'pitch shift' a straight one with +/- 4 semi-tones, and one with Echo.

Just throwing it out there ...

[~arph]

Looks like a cool IC, you can program it yourself, not too expensive either

[flo]

Yes, looks like an interesting chip. But how to create a good board for it and solder it. Its smd. 
Or just get the evaluation board (a bit expensive at 90 pound => 170 dollar)? If  you want to program it, you probably need one anyway.
Then perhaps the upcoming Line6 Tonecore DSP kit is a more interesting option at $199,-
Its also programmable from a PC, has USB connection, 24bit AD/DA, code examples, Tonecore stompbox like enclosure... hmmm looks very interesting!