Axoloti Core & Derivatives

UltraBlack · 2023-07-22T13:05:41.514Z

That’s great to hear! While we’re at it, I’d have a few suggestions:

Could you sell this shield or whatever follows separately as well (at least as a full kit, soldering shouldn’t be too hard)? Creating one yourself would be a whole new entire hassle and I’ve never sourced parts for a PCB either. I’m also thinking that it wouldn’t hurt if the screen was one to two rows taller. I think this is almost a little too small to show useful information
Talking about IO; Could you include the midi and audio jacks (yes plural, preferably multiple TRS in- and outputs - for balanced audio and just to have multiple inputs. I’m thinking of a device that can run multiple effects on multiple stereo audio sources at once ) on the board itself, or at least also provide a shield with that? Same story as above. this seems a bit clumsy to handle. I think it would be best, if everything was one solid piece at least.

I don’t know how realistic my suggestions are, but I’m just hoping that I will not have to do any PCB designing and part sourcing myself. I’d like to keep tinkering to the software, because that’s exclusively where I have knowledge

UltraBlack · 2023-07-22T14:55:02.208Z

sebiik:

Or at least make a more spacious version, with bigger OLED (1.3inch 12864 = double the size), more knobs, buttons or encoders, audio (2 1/4" in, 2* 1/4" out) and MIDI jacks going to the rear. Possibly even with stomp box foot switches

Oh that would be great!
So you are saying, that the in- and outputs will be mono each? Could make use of these in-socket switches? It would allow for using one jack for both channels instead of one jack for each channel.

Clarification for the switch

image1279×1280 52.9 KB

sebiik:

I could be completely wrong here since I never worked with balanced audio but my point is the Axoloti is too small and simple for any of that.

That’s fine by me. I was just trying to come up with some ideas why else four input channels could be useful.

sebiik:

Multiple Ksolotis

Do you have a price estimate for a ksoloti yet? If each one would come in at 150€-200€ it would be a bit much for just two more channels in my opinion.

Maybe also just a little to complicated, but if you were able to stack ksolotis on top of each other for shared IO, Memory and Processing power, I think that it could have a ton of potential. I mean if you’re short on ram and processing power, you could just add another ksoloti to the stack

sebiik:

precious RAM

What about adding more ram modules if you are gonna make the board bigger anyways? You could also have really huge delays and reverbs with more space available there

UltraBlack · 2023-07-22T19:58:29.697Z

oh also: Will there be a micro-SD card slot? I think this device would make for a good sample player with all that IO

Hitachii · 2023-07-22T22:40:03.765Z

There appears to be a micro-SD slot on the pictures on @sebiik’s instagram, so I think you’re covered on that front.

Shimoda · 2023-07-24T11:04:56.061Z

Interested in this ksoloti

MagAmp · 2023-07-30T05:47:07.658Z

Hey @UltraBlack,
Hmmmm… you are suggesting adding balanced audio, and asking about

UltraBlack:

multiple effects on multiple stereo audio sources

Are you, by random chance, thinking loudspeaker crossover networks? Interesting, because that is one of my applications, but it probably wouldn’t make sense to add balanced audio to the basic ksoloti core board because:

There isn’t much room
Not many people will need it
For people who -will- need it, like high fidelity audio users, it should probably be on a daughterboard anyway, because how it would be configured would likely be very application dependent.

What is your application?

Hey @sebiik, all.

sebiik:

Anyone interested in the tech background and header pinout, here is the most up-to-date schematic in PDF format.

Everyone should be aware that @sebiik has put A LOT of thought into this ksoloti core thing. I think his most important objective was simply to minimize any deviation that would affect compatibility with the most recent stable axoloti code base, 1.0.12-2. Anyone who is familiar with Akso, will immediately appreciate this!

But also, the idea is to:

Beat the price of axoloti
Make it usable standalone, by just soldering on the 3.5mm headhone jack on the back
Make it useable as the basis for a 12hp Eurorack module
Make it useable as the basis for a desktop (probably MIDI) device
Make it useable as the basis for an effects pedal

Many compromises were made in the process of doing all this, and some of them are probably imperfect compromises. But you have to start somewhere, and I think @sebiik has done an admirable job negotiating the minefield of scope creep.

Regarding Johannes support / endorsement of this ksoloti thing, @sebiik has been trying to get hold of him for quite a while, to discuss it. My conclusion is that Johannes certainly must know about it by now, if he’s been watching the forums. And in a sense, I think we can probably interpret his lack of comment as tacit support.

Anyway the design is open source. An immense debt of gratitude is owed to Johannes, TheTechnobear, nsm, and others for the existing status of the patcher and the axoloti environment.

Continued development of this environment is the most critical factor to push the capabilities of axoloti. The ksoloti hardware is just a means to that end.

Hardware upgrades can and should happen too, and STM32H743 has me salivating, but in the meantime we’re going to have a working ecosystem. @sebiik has had the insight to recognize that that is the most important first priority.

UltraBlack · 2023-07-30T14:35:16.800Z

MagAmp:

loudspeaker crossover networks

Until ten seconds ago I had no idea what that was haha. No that’s not my goal.
I’m thinking of getting my first dedicated FX unit soon, and I’m on somewhat of a tight budget, so I just want to get as much out of it as possible.
The ksoloti would allow for an FX unit that I can shape and tinker with any way I want to, and I’m trying to think of every possibility that I could use it for and suggest missing features on that basis. My end goal is to keep all of this as cheap as possible.

I’m still not entirely sure if this device is a wise choice as a sole FX processor anyways. I don’t know if I’m capable of programming a nice delay or reverb effect.

Maybe I should just get a flashback 2 for delay. Somebody tell me what to do haha

rvense · 2023-07-30T15:10:17.566Z

Do you want to make one or need (“need”) to have one?

A nice sounding reverb from (something approximating) scratch is no small feat. I don’t know if there are any good reverb blobs for Axo these days, but even then I think it would make the most sense if you’re expecting to tweak it over a longer period of time.

UltraBlack · 2023-07-30T16:40:39.151Z

Yeah I do “need” an FX pedal/processor.

rvense:

A nice sounding reverb […] is no small feat.

That is to be expected. I was hoping that I could find an article of some sorts where I can find out how to do this. I am in luck though. one of my synths already has a pretty bonkers reverb built-in. Maybe I can just take that and rewrite it to be compatible with the ksoloti. That synth really has to work around memory limitations, so I’m expecting a standalone one to be much cleaner and less down-sampled.

A delay should be somewhat easy to implement since pretty much all of it’s variations just take the in- or output from the delay loop and modify the audio in some way.

The only issue is that I have zero FX programming experience. I’m now wondering: Is there a way to run this graphical axoloti editor standalone or even write and run axoloti code without one attached? It would allow me to try it out and see if I could actually use it

Edit: This is one of my two synths; Yes the codebase is a bit of a mess, but it seems somewhat usable. Looking at parts of the delay and reverb code, I’m thinking that I maybe should just get a dedicated pedal for that

github.com

Ixox/preenfm3/blob/617543edcd2b61a3dda1da247c53688dbbf71b7d/firmware/Src/synth/FxBus.h

/*
 * Copyright 2021  - Patrice Vigouroux
 *
 * Author: Patrice Vigouroux (Toltekradiation)
 * Forum discussion : http://ixox.fr/forum/index.php?topic=69835.0
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef FX_BUS_
#define FX_BUS_

This file has been truncated. show original

github.com

Ixox/preenfm3/blob/master/firmware/Src/synth/Timbre.cpp#L1587


      
          delayWritePosF = (float) delayWritePos;
          
          // predelay
          delayBuffer_[delayBufStereoSize + delayWritePos] = low1;
          int wp = (delayWritePos - delaySizeInt) & delayBufStereoSizeM1;
          
          // hp
          float hp_in_x0 = delayBuffer_[delayBufStereoSize + wp];
          hp_in_y0     = _hp_a0 * (hp_in_x0 - hp_in_x1) + _hp_b1 * hp_in_y1;
          hp_in_y1     = hp_in_y0;
          hp_in_x1     = hp_in_x0;
          
          delayBuffer_[delayWritePos] = hp_in_y0;
          
          float hpComplement = hp_in_x0 - hp_in_y0;
          
          //--------------- shifter 1
          
          delayReadPos = modulo(delayReadPos + currentShift, delayBufStereoSize);
          delayReadPos180 = modulo(delayReadPos + delayBufferSize90, delayBufStereoSize);

UltraBlack · 2023-07-30T17:53:20.226Z

I got curious and tried out the editor. I not only did not find out in what way the expert mode allows me to run code locally, but I was also greeted by a compilation error, because it was somehow unable to find a library. I don’t know what this tool does behind the scenes, but it definitely has some weird and apparently broken cross-compilation approach.

Good new is that there actually is a delay and reverb patch that you can edit in the editor. Somehow though, I completely lost that after opening it once and I haven’t been able to find it for like 15 minutes now (weird).

Hope remains!

Edit: I see. Expert mode allows you to compile the code, which you can’t manually do normally
Edit 2: The entire application seems really buggy and barely usable. I think the reason why it’s not working anymore is that I can’t open the menu to add new objects.
Edit 3: I finally found the reverb patches! Help → Library → Factory → Reverb

UltraBlack · 2023-07-31T04:51:53.403Z

sebiik:

Sounds like version 2.0 to me?

That is completely true. I just now checked the official stable release and it’s also not less broken. The “Add Object” menu still opens once, closes shortly after and never opens past that point again.

sebiik:

hear your patch without an Axoloti connected

Yes exactly. that was my goal.

Well regardless: My main question right now is, if I can actually hope for a great FX module when I get the ksoloti at some point. I now know that the software allows you to work with time FX but I want to make sure that this is not downsampled into decimation. I know how bad a downsampled reverb can sound - What can I expect from the new hardware?

UltraBlack · 2023-07-31T07:28:01.661Z

well I did not expect to find anything, and all I found in the end is this single sound demo, but god damn.

UltraBlack · 2023-07-31T07:34:44.659Z

didn’t you start backing up the forum?

anon60283851 · 2023-07-31T09:42:23.197Z

While I never ended up trying them out (currently only have a half-working original Axoloti) it sounds like TheSlowGrowth’s MPE synth demo has pretty nice reverb built in to the patches as well:

UltraBlack · 2023-07-31T10:55:18.651Z

Woah. What a sound, for such a small device. I would have never thought that it could sound like a multi-thousand Dollar setup.

This reminds me: ~~This linnstrument among~~ other midi controllers (like this relatively cheap one) only use MIDI over USB for some obscure reason. I think the ksoloti could also use at least one usb port.
I’m also thinking it would be really nice if there were several modules that you could plug into ksoloti as some kind of pcb stack. Maybe one for pots, displays, buttons, etc, and one for ports, like additional jack sockets and usb ports.

anon60283851 · 2023-07-31T11:26:59.148Z

Yeah, those are very, very good sounding patches based on the demos. Of course the Linnstrument has a lot to do with it as well as you can modulate things quite easily with your fingers and make it sound even more lively.

FWIW Linnstruments (both full size and 128) do have normal hardware DIN MIDI ports, and that Nakedboards one has a normal MIDI out with a 3,5mm jack, that you can convert to DIN MIDI with a passive adapter. So all hope is not lost!

JES · 2023-07-31T12:49:30.164Z

Chiming in to say I got to try out a Linnstrument with an Axoloti a few years back and was immediately sold. The synth engine was “just” an MPE port of Plaits but sounded fantastic. The Axoloti was already unobtainable at the time, so I’m excited to see this project develop.

And yes, both my 128 and 200 have DIN MIDI outs.

UltraBlack · 2023-07-31T12:51:03.048Z

oop thanks for clearing that up, I have no idea how I misread that so many times.

Well the nakedboards one has a TRS midi connector, but things like these don’t. I’m not a fan of AKAI quality, but other people use these.

Hitachii · 2023-07-31T16:01:43.338Z

MagAmp:

STM32H743 has me salivating

iirc this is the mcu used in the Synthstrom Deluge which just went open source. No doubt that would be a handy resource if trying to adapt the axoloti code to work with it.

As I’ve been saying since Axoloti inspired me to start coding, one of these days I’ll be competent enough to help out!

anon60283851 · 2023-07-31T17:18:20.310Z

Deluge is using a Renesas MCU (can’t remember the exact model number), so STM is a different manufacturer. Both are ARM CPUs though, the Renesas used in Deluge is A9 and that STM part is A7 I think…