Arpy Mod Board for PT 2399 Delay like Midifi Pirate Deluxe: Clarinote, etc

[Babajoux]

Hi,

I wanted to do an ARPY kind of Pedal.. Pitchshifting notes.. and then I tried stuff out with the PT2399 cause if you manipulate the Oscillator on Pin6 it does kind of pitch shifting thing..

several resistors in series together with a multiplexercontroled by a binarycounter  change the pitch.

I decided to make a little sister board for the pitch pirate, the project startet actually with with the WRAA! retroflect but then i had the pirate already in a box and wanted try out how it sounds together. You can use nearly any PT2399 Delay.

You could also do a single effect by combining it with one and put it in a box. I have to boxes connected via a cable..

You get weird tapy sounds, Ringmod sounds, blips and blops, vibratoish.... ghoslty, spacy, robotish computer sounds.

[Mark Hammer]

In the late '70s, EHX came out with the Hot Foot controller, that let you physically rotate any pot with your foot.  One of the "killer apps" for the Hot Foot was working the time delay control on a Memory Man to do pitch shifting.  This was well before the Digitech Whammy was a gleam in anyone's eye.

Of course, the pitch change was continuous, or rather as step-like as you could work the Hot Foot's treadle.  The Chase Bliss Thermae adopts a derivative of this differential sample-in/out by directly jumping between different sample-in and sample-out rates, via the internal microcontroller, rather than pot-twiddling, to achieve predetermined interval jumps on the repeats.

Does your circuit do something like that?

[ElectricDruid]

I had a crack at this too:

https://www.diystompboxes.com/smfforum/index.php?topic=122859

I simply used a vactrol's LDR to control the delay time, and then fed a digital LFO to the vactrol's LED. Got pretty wacky pretty fast.

[Babajoux]

Yes in a way, the resistors of the multiplexer form the pattern of the the pitch change. Here you can change the speed with the lfo and the direction with a switch and the /depth/stretch with a knob. Sometimes changes are not that obvious or extrem like i wished for, e.g. with the direction up or down, but its a start. With a mikrocontroller there would be definitly more possibilites. 

I try to make a sound sample asap than you can listen to it.

[Mark Hammer]

Important to note that pitch changes resulting from sample-in/out differences are in the repeats and not the first delay.  In other words, you can't change the playback rate of the sample until you have acquired the sample.  So, first repeat is at pitch, but subsequent repeats can be at other pitches.

[Babajoux]

Thanks for the clarification.. there is so much I don't really understand. But that's the fun for me - to explore!

Hi, I managed to upload a sound sample video for the circuit. I hope it gives you an better idea of what it's doing.

I started to read into the bucket brigade chips that are in the thermae pedal. It seems to me you can tweak them more or differently than the pt2399 chips. I always wondered how you can reverse a sample? And I wonder if it's really possible to get hold of a sample in a pt2399. I don't see it, maybe I am blind. Or is it when people set them in series to get a longer delay time or different tape heads?

[Babajoux]

I made a new Schematic added some resistors and a switch which lets you chose between a modulated an non modulated Arpy tone " no wobbly sound". I also missed to isolate one one the LDR, so they influenced each other in the video example.   

[anotherjim]

I can't think of how you could reverse the sampled audio in either a PT2399 or a BBD. Probably you can fake it by applying a slow fade-in attack. Something like a Roland Slow Gear acting on the delay output. A proper approach would be DSP based with some clever buffering and level detection.