Using axoloti for MIDI syncable stereo/ping pong delay?

#1

Hi all! I'm considering getting an Axoloti core for the sole purpose of making a stereo panning/ping pong delay that optionally can be MIDI time synced.

I did some searching and found some existing sub-patches like https://sebiik.github.io/community.axoloti.com.backup/t/drjustice-contributions/1459/29 and objects like MSPP delay https://github.com/axoloti/axoloti-contrib/blob/1.0.12/objects/sss/delay/MSPPdelay.axo

So my question is how good a fit Axoloti is for this purpose? And how well do these existing patches/objects work?
Does anyone have any experience with using an Axoloti Core for stereo/ping pong delays? How well does MIDI clock sync work?

And is it possible to store and recall settings/presets for a patch one has made without being connected to the computer/patcher?

#2

Hi, I used Axoloti to do that. Soundwise the Axoloti performs very well, you can do ping-pong, multi-tap, tape, filtered, very long delays (If you use a micro SD card), and other things (delays don't eat much DSP).
About syncing to MIDI, I had mixed results. I did a patch that sync perfect to my computer, but the same patch synced to my Beatstep produces glitches (even with a steady tempo), I know there is a way to implement a smoothing of the clock to avoid that but never tried as most of the time I sync to my computer...

#3

You say

"very long delays (If you use a micro SD card)"

I thought that writing to the SD card seamlessly was not implemented, I quote from a 2016 comment on looping:

"for longer loops this means you need to consider streaming to SDCard.
currently there is streaming playback, but no optimised writing to SDCard (afaik) , and its not trivial (though not impossible) to implement."


¿Do you know if optimised writing to the SD card has been implemented since then?

#4

Thanks for sharing your experiences. It sounds very promising!
I guess I'll just order an Axoloti Core once they're available again and give it a try.

Did you use any third party objects to build your delay? Or all standard ones? Any chance you could share a patch?

Regarding MIDI: I'd want to sync to my sequencer (a Digitakt), so I guess I'll just have to try that. We'll see if it works :slight_smile:

#5

I didn't have any problems writing/reading from SD Card, I think it's optimized (I have my Axoloti for a year, so I didn't try old firmwares).
For my delay I used a patch from the community library and changed some things to my taste.

#6

The Axoloti has 8 megabytes of DRAM on board, which theoretically is enough for over 43 seconds of delay (32 bit audio at a sample rate of 48000 kHz), or twice that if optimizing the delay to use 16 bit audio only. So if that is enough for you you don't need to used the SD card.

#7

You aren't taking in account that the patch itself is loaded into DRAM, if you want to use only the delay and some clock I/O may be the DRAM will be enough, but I'm always run off DRAM in my patches...

#8

No, the patch itself is running in the on-chip memory in the STM32F427 chip, which cannot even execute code directly from DRAM if I remember correctly. If one doesn't use the special objects which allocate memory in DRAM, then delays will indeed compete with the code though as they also allocated in the on-chip RAM.