KA-303 (dev here): a 303 built around a fast acid composing editor

[Frank_Kreuzberg-Audio]

Hey everyone,

Dev here, so the usual disclaimer applies. Saying it up front so this isn't a stealth plug.

Yes, it's another 303, and I know this forum has a whole thread full of them. So the honest reason I built it: I didn't want another clone. I wanted the real squelch as a base and then a proper writing workflow on top, because that's the part every 303 I owned made painful.

The core is a real 303. Component-level diode-ladder filter with zero-delay feedback, and a square modeled off the way the hardware clips a saw through a single transistor, per-voice drift included. So it reacts like the real thing. I'll let the demo handle that claim.

The composing editor is the part I care about most. The whole point is getting from nothing to a finished acid line in seconds instead of drawing notes one at a time. Scale-locked grid, so wrong notes aren't possible. Drop a few steps or drag in a MIDI file, then let a handful of knobs do the work: Scramble, Mutate, Density, Octave Jumps and a Groove control that shifts the feel from tight to laid back. Slides and accents go straight into the roll. Pattern lengths run 1 to 32 steps, and odd lengths like 3, 5 or 7 drifting against the DAW's 4/4 grid give you that Hardfloor pull that builds and resolves over bars. When you like it, drag the MIDI back into your DAW. Sound presets and pattern presets are separate banks too, so you can leave a line running and click through completely different sounds under it.

There's more under the hood (a Flavor Palette of character engines, four acid distortions with a clean-sub crossover, unison, the usual FX), but it's all on the page and I'd rather you just heard it. Pure sound, no talking:


It's paid, but there's a full demo with no time limit, so the honest move is to just try it in your own DAW. It fades in a bit of noise every 30 seconds and mutes after 30 launches, that's the only catch:
https://kreuzberg-audio.com/en/download ... nthesizer/

If you do run it, I'd like to hear where it falls short, the sound and the filter behaviour especially. And if it's not for you, no hard feelings, there are some solid free 303s around here already.

Cheers,
Frank

[Paul_Pulsonix]

sounds good, can you modulate the settings ?

[Frank_Kreuzberg-Audio]

sounds good, can you modulate the settings ?

Hey,

thanks a lot for the feedback, really appreciate it!

Just to make sure I get you right: what exactly do you mean by modulating the settings? Are you talking about modulating specific parameters, or something else? A quick example would help me a lot, then I can give you a proper answer.

Cheers,
Frank

[whassup]

Ruhig Grosser, ruhig...
Juut juut sach ick wa, dann hör ich mir tatsächlich die janzen fuffzehn ein halb Minutn an.
Und det knarrzt, zwitschat und schnattert nur so vor sich hin.
Nomma: Ick will doch ja keene drei null drei!
Mann, leider endgeil...

[Paul_Pulsonix]

In the vid you are twisting the knobs, it would be nice to have build in modulation so they can move to the sound evolves. like my app hass, or serum.

[Frank_Kreuzberg-Audio]

In the vid you are twisting the knobs, it would be nice to have build in modulation so they can move to the sound evolves. like my app hass, or serum.

ah, now I get you! That is a really great idea. Built-in modulation so the knobs move on their own and the sound keeps evolving, kind of like in Serum. I love that.

I will definitely put this on the roadmap and make it happen. Thanks a lot for the inspiration, this is exactly the kind of feedback that makes the plugins better.

I will keep you posted once it lands in an update.

Cheers,
Frank

[Frank_Kreuzberg-Audio]

Ruhig Grosser, ruhig...
Juut juut sach ick wa, dann hör ich mir tatsächlich die janzen fuffzehn ein halb Minutn an.
Und det knarrzt, zwitschat und schnattert nur so vor sich hin.
Nomma: Ick will doch ja keene drei null drei!
Mann, leider endgeil...

Na Lars,

ick hab wirklich juut lachen müssen bei deiner Nachricht. Fuffzehn ein halb Minuten durchjehalten, obwohl de jar keene Drei-Null-Drei willst? Dit nenn ick mal Hingabe, Respekt! Und wenn dit Ding knarrzt, zwitschat und schnattert wie ne Entenfamilie uff Speed, denn ham wa allet richtig jemacht. Genau dafür isse ja da.

Und "leider endgeil" is sowieso dit schönste Kompliment, dit man als Acid-Schmied kriegen kann. Kommt sofort in die Vitrine.

Vielen Dank für dit Feedback! Und wenn de mal in Berlin bist: Komm jerne bei mir im Riverside Studio vorbei, denn schrauben wa jemeinsam an den quietschenden Knöppen, bis de doch noch schwach wirst.

https://www.riversidestudios.de/

Cheers, Frank

[Paul_Pulsonix]

In the vid you are twisting the knobs, it would be nice to have build in modulation so they can move to the sound evolves. like my app hass, or serum.

ah, now I get you! That is a really great idea. Built-in modulation so the knobs move on their own and the sound keeps evolving, kind of like in Serum. I love that.

I will definitely put this on the roadmap and make it happen. Thanks a lot for the inspiration, this is exactly the kind of feedback that makes the plugins better.

I will keep you posted once it lands in an update.

Cheers,
Frank

Maybe it's already possible to add automation in the DAW, I didn't try the demo yet, should be if it's made with JUCE.

[Frank_Kreuzberg-Audio]

In the vid you are twisting the knobs, it would be nice to have build in modulation so they can move to the sound evolves. like my app hass, or serum.

ah, now I get you! That is a really great idea. Built-in modulation so the knobs move on their own and the sound keeps evolving, kind of like in Serum. I love that.

I will definitely put this on the roadmap and make it happen. Thanks a lot for the inspiration, this is exactly the kind of feedback that makes the plugins better.

I will keep you posted once it lands in an update.

Cheers,
Frank

Maybe it's already possible to add automation in the DAW, I didn't try the demo yet, should be if it's made with JUCE.

yes, absolutely, that works for sure. All parameters are exposed to the host, so you can automate everything directly in your DAW.

The reason I have not built in dedicated internal automation or modulation yet is simply that I am a Bitwig user myself, and Bitwig already comes with modulators for everything, so I never really felt the need. But you are right, for people on Logic or other DAWs it is actually a really good idea. I will put it on the list.

[audiojunkie]

It sounds really good! I love that there is a working pattern editor that has the slides and accents, and allow you to do true acid slides. I love that you support Linux!! I only wish your copy protection could be like U-he, Plogue, and others where it wasn't vendor dependent. I usually only buy software that doesn't use challenge/response or call home. My ideal, is to be able to archive the software and the authentication together on a backup drive, and then be able to, at a future date, install the software and authentication on a new computer, even after a company is gone or has discontinued support for the product. There are many that provide authentication like this that doesn't punish the honest more than the pirates. Pirates, you know, will never pay for the software. But the honest will pay for the software if it provides for their needs.

You have a really nice sounding product! I use Linux, and would usually jump at a chance for a good sounding synth like this (especially because it has a working pattern editor with slides and accents). Maybe someday you'll choose to do as other developers have, and change your copy protection. In the meantime, I wish you the best of luck in your business!

[michat]

Geiler Scheiß, echt! Hätt' ich nicht schon eine Emulation auf Softwarebasis und eine in Analog, würde ich mir das Ding glatt kaufen. Doppelte Props und viele Grüße aus dem Ruhrgebiet

[Frank_Kreuzberg-Audio]

In the vid you are twisting the knobs, it would be nice to have build in modulation so they can move to the sound evolves. like my app hass, or serum.

ah, now I get you! That is a really great idea. Built-in modulation so the knobs move on their own and the sound keeps evolving, kind of like in Serum. I love that.

I will definitely put this on the roadmap and make it happen. Thanks a lot for the inspiration, this is exactly the kind of feedback that makes the plugins better.

I will keep you posted once it lands in an update.

Cheers,
Frank

Maybe it's already possible to add automation in the DAW, I didn't try the demo yet, should be if it's made with JUCE.

yes, absolutely, that works for sure. All parameters are exposed to the host, so you can automate everything directly in your DAW.

The reason I have not built in dedicated internal automation or modulation yet is simply that I am a Bitwig user myself, and Bitwig already comes with modulators for everything, so I never really felt the need. But you are right, for people on Logic or other DAWs it is actually a really good idea. I will put it on the list.

Hey Paul,

remember your idea about built in modulation, so the knobs move on their own and the sound keeps evolving like in Serum? It is in. KA-303 v1.6.1 is out and it gives the synth something it never had: a complete modulation system. Your acid lines can move now.

The centerpiece is the new MOD tab. Assign almost anything to almost any knob:

3 LFOs for classic cyclic movement, so filter sweeps, wobble, tremolo.
2 mod envelopes, including a true one shot AD mode for per note shaping.
2 freely drawable curves for sketching your own modulation shape by hand.
A step sequencer, 1 to 16 steps, for rhythmic, pattern locked movement.
4 macro knobs to grab a whole handful of parameters under one control.
Performance sources like velocity, accent, note pitch, mod wheel and random, so the synth reacts to how you play.

Assigning is deliberately simple: right click any knob, pick a source, done. A colored ring shows the modulation depth right on the knob and a live dot moves with it, so you always see what is going on. Every routing saves with your preset and your project.

It is all additive, by the way. Your existing sounds are exactly as they were, modulation only moves what you tell it to.

And there is a whole new pile of sounds to go with it. 158 presets now, up from 79. Every factory sound got a "(modulated)" twin: same foundation, but in motion. Slow filter sweeps, breathing character parameters, living spaces. All tuned by ear, slow and smooth, never nervous.

A few more things that landed in the same update: multi level undo and redo in the Composing tab (Cmd+Z / Cmd+Shift+Z), five new modulation targets in the pre distortion filter, tooltips on every control, and a cleaner tab order (Sound, Modulation, Composing, Settings).

The update is free for everyone who already owns the KA-303. Just log into your account and grab the new version:
https://kreuzberg-audio.com/my-account/

Install it right over your existing version, your presets, licenses and projects stay untouched.

And if you have not got it yet, the demo is here:
https://kreuzberg-audio.com/downloads/k ... nthesizer/

Thanks again for the push. This went straight from your post into the roadmap and now into the plugin. Would love to hear what you build with the new modulation.

Cheers,
Frank

[audiojunkie]

Nice! This is getting quite appealing.

[Paul_Pulsonix]

sweet, I'll check it out sometime and compare with my Behringer TD3-MO.
That's how fast it can go, lots of changes in my app also came from requests here on this forum.