Soul Crusher - decimator, sample rate modulator, and curve mapper

I was inspired by the Geiger Counter pedal and how it aggressively seems to use a few simple operations to make such a fun tone. This is my first attempt at a general-purpose patch and one that is (hopefully) somewhat decently documented. Any critique is appreciated!

Soul Crusher.audulus (8.4 KB)

My goal is to create a decent noise gate so I can use this with my guitar on my ipad as a harsh effects pedal work-alike.

Please share any feedback you have since I’m eager to get better. I want to make some patches that, come Audulus 4, other people find useful :slight_smile:


Looks good! the only suggestion I would make would be to use the sample rate node when making calculations about the sample rate, since Apple is now default 48 khz but some users have 44.1khz running.


Welcome to the forum! Always good to have another contributor. Nice patch. It’s well laid out and documented and it’s an interesting effect. A couple of minor points in addition to the sample rate node that @robertsyrett mentioned. It would be better to avoid using the legacy knob that provides a label and adjustable range. It’s been deprecated in favor of the clamped knob. Because the original knob doesn’t have a hard-coded range, modulation of the knob was a bit unpredictable. When modulated by an external signal, the knob will output whatever value is applied. Modulation values outside the range that the initial module designer intended often resulted in unpredictable behavior.
To address this, the community adopted a de-facto standard for modulation signals of 0 to 1. The clamped knob enforces this standard by ensuring that any modulation of the knob will remain between 0 and 1. This makes sharing modules a bit more predictable. The clamped knob can be labeled using a text node or SVG graphic. Note that the clamped knob is currently not available in the macOS AU plug-in. The AU is scheduled to be updated to AUv3 with the release of Audulus 4 so no further updates to the current AU are planned.
Regarding the unit delay, I don’t believe that it is necessary. Since the S&H node is gated on the rising edge of the trigger, the pulse width isn’t critical. A simple 50% duty cycle square wave should be fine.

FYI, all of the signals in Audulus are 32 bit floating point values so a max setting of 16 bits implies a 50% reduction in bit depth, not that it will really be very noticeable at that setting. I haven’t wrapped my head around the idea of a fractional bit. I’ll have to give it some more thought. In any case setting the range to 32 bits would likely result in an overflow in your calculations and probably wouldn’t make any difference in the sound.


Nice patch/module (definitely usefull :smiley:)

This reminded me that I built a noise gate some time ago that I hadn‘t uploaded.
I don‘t know if it is exactly what you want, but it is enough for my needs, so I uploaded It here:

I’d also like to add something to the whole ‘clamped knops’ thing.
The iOS version of Audulus doesn‘t have clamped knops in it‘s node browser. You’ll have to copy them from another patch.
clamped knob.audulus (306 Bytes)

1 Like

Thank you all for you feedback. I’m gonna try to reply to stuff, but I’m really new to these forums so things might go silly.

I actually intentionally made the decision against using the sample rate node since I wanted the same knob position to have the same effect, regardless of the sample rate that the user has their document running at. But I realize that having an “effective sample rate” over the nyquist rate will really break things, so I should probably bring the max down to 20kHz or around there.

I want to thank you and @J301 for pointing this out, but since I only run the iOS version (for now. I can’t wait for A4 and to get it on multiple platforms), I didn’t know there was a better control. I’ll try swapping it out to make the patch easier to control.

This was me having a brain fart and thinking a phasor went from 0…1 instead of 0…2pi. I tried having an expr node with x>0.5 as the condition, but for some strange reason it didn’t work right. Removing the unit delay would absolutely make this better.

I chose to go with 16 bits as a “max” level since it is used (with integer, not float) samples for most commonly shared sound. And as to fractional bits, I’m trying to use them in the more information-theoretic context where “3.7 bits” implies that there are 2^3.7, or almost 13 distinct values for the output. I’m off by almost a bit in my calculation since I have all of my math being done as zero plus choices being either above or below zero (so with “3” bits, there would be (2^4)-1 possible outputs.

Thank you all for the feedback, I’m going to try to improve this patch over the next few days and want to post an updated version of this.



But actually that makes sense, considering the degradation of sound is the key thing.

These types of waveshaping odessies are really what keep me coming back to the Audulus well for new sounds.

1 Like

I’m glad to know this was at least a somewhat sane decision. Aside from the z^-1 node, this was the part I was the most unsure of.

And darn, I’m now totally hooked on uploading modules here. Is there that much of a feature advantage of using the mac version versus the iOS one? I’m not eager to buy a new version in advance of buying two copies of version 4, but if it’s that’s much of a difference, it’s worth it.


Mostly just one less step to get patching. An idea floats into my head and I can save a patch real quick to come back to later.

I suppose there are a few extra nodes like clamped knobs and SVG placement that are fun for customizing as well. Those are nice but not necessary.

SVG examples…audulus (562.9 KB)



Thanks! But with a $50 purchase cost, I’m gonna have to wait for version 4. Guess I just need to do the best I can on limited hardware for now :slight_smile:


An admirable attitude. Naturally feel free to ask for help if you want an SVG applied to a module by a desktop user.

1 Like

Also, the clamped knob and SVG graphics are supported on the iOS platform, so you can simply copy/paste them from an existing patch. Both of these anomalies will be corrected in V4. @Taylor decided against investing further programming time in V3 in favor of working on V4. As @robertsyrett pointed out the macOS version is a bit faster when constructing patches. For large patches, the larger screen size available on a Mac is also useful. Depending on your iOS device and Mac, it’s also able to run much more complex patches without running out of CPU and supports multiple sample rates. I frequently create patches that won’t run on my admittedly somewhat obsolete iPad Air 2. The other major difference IMHO is the quality of DAW software available on the two platforms. Although iOS DAW software had made great strides in the last few years, I still find macOS based programs much easier to use. The current Audulus AU hasn’t been updated in quite some time and has some stability problems so currently I’m running it standalone on my Mac and feeding the signal into Ableton Live via an analog connection or using SoundFlower. The introduction of a new AUv3 with version 4 of Audulus should make DAW integration much easier on both platforms and in the end it will largely be a matter of personal preference.

1 Like

I have both and primarily patch on my iPad out of convenience of being able to patch on the go.

Sometimes I start on a MacBook, then when the CPU gets high, I work off of my phone. The cellphone explosion has made the phones so darn powerful. Lucky us. That aside, one of the biggest workflow improvements I did was when I made the Old Forum Patch Collection, as well as the Reface Library, available from the side menu.


That’s a super handy trick, right? I did that a while back when watching @robertsyrett’s ‘know your nodes’ videos, and it has been a super helpful organizational tool.

Nothing is more metaphorically painful than menu diving when I am trying to hold onto the inspiration that I am just barely grasping with just my thumb and one finger, at that particular moment as it is slowly slipping out of reach. A lot of ideas have come and gone from my head because I wasn’t able to get to the right tools before my mind wandered somewhere else, and the idea was gone.

With that being said, I have the Reface Module Lib, but I don’t have the old forum modules. Can anyone provide me a link to download them all, if possible?

Nice to see you around some more.


Dope! Thanks man :slight_smile:

1 Like