Beta testing of Vult filters

I’m preparing a new release of the Vult modules which features a few bug fixes and improvements. One of the improvement is that I have reworked the simulation engines of some of the filters. This results in improved performance and support for the full range of sample rates that Rack v2 provides. The behavior of the filters is slightly changed in higher frequencies but I believe they sound better.

Before I push the official release, I thought that it would be good to let you folks trying them to see if you find any issues.

You can get the binaries for the free modules here: Release Improved filter versions · modlfo/VultModules · GitHub

Please let me know if you find any issues.


Hi Leonardo.

Thank you for your continued efforts in improving the Vult VCV plugs.

‘Lateralus’ module still output low voltages for me when operating at sample rates exceeding 192kHz. Same steps / setup as per original ticket

Will update the ticket with some further findings later.

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I’ll give you some feedback when I have time. My test rig is EVERY PATCH I’VE MADE FOR THE LAST 5 YEARS, since I use vult filters in everything I do.


I made a mistake and the only filter that has the new implementation is Tangents. Lateralus and others still use the same old algorithm. I’ll publish a new build when I have the implementations.

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I’ll gonna test these asap

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I have updated the binaries. Now Lateralus uses the new algorithm which consumes about 1/5 of the CPU.


Leonardo, thank you.

I haven’t yet conducted a comprehensive analysis, but I have experimented with some straightforward crosspathing and audio rate modulation. The outcomes have been satisfactory so far.

Can we anticipate that the new algorithm will be incorporated into all Vult filter-powered modules, such as Incubus and Freak?

Yes. It will be included in the other modules and the hardware as well.


I tried the new version of the free filters.
here (Win11, VCV 2.4.1) they work fine

Thank you Leonardo,

it fixed Tangent and Lateralus for me, which weren’t working anymore. Stabile has a bug tough : when passing 0,850 cutoff, the filter shuts down in a swift whistling and is not coming back.

Made a test setup. I copied the VultModulesFree folder and renamed it VultModulesOld


Changed the plugin.json inside the old folder to :


Then I added the new one from github, restarted Rack, and can now use the old next to the new :

What stands out in this setup is, Tangents at higher cutoff all (HP LP BP), and Lateralus is tuned differently (see pic)


Here is the test preset :

Vult test - 27112023.vcv (6.1 KB)

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now I have a nanV out from the new Tangents version

I have encountered ‘nanV’ output too twice today. However, I am still unable to pinpoint the exact root cause of this behavior.

Simple patch, one VCO is passed through Tangents, self-patching with the Cutoff, Res, and Drive inputs being modulated by module’s own output signal. The corresponding attenuverters were set to their maximum levels.

I used the standalone version of VCV Pro, with the engine frequency configured at 768 kHz running on Win 10.

Module initialization through the module menu does not help, only viable workaround to reset Tangents’s output appears to be a complete restart of the VCV rack itself.

768 kHz? wow, you must have bat ears, I doubt anyone tests at that sample rate. I (having decidedly aged ears) can barely detect a difference between 48kHx 24bit and 96 kHz 24 bits, let alone anything higher. I have tried to get the beta Tangents to output NaN but so far it’s been fine, but I do run at 48 kHz, your mileage and platform may differ…

I wish so :slight_smile: That the sampling rate i am using here is purely for testing. As Leonardo pointed out, new algorithm is designed to support the full spectrum of VCV sampling rates. Therefore, it’s advisable to conduct tests for edge or borderline cases to ensure the module can handle the extreme values within the valid limits.

In my experience with VCV, i often operate at higher sample rates during what i would call the ‘design phase’ of my audio production process. This is particularly true when working with FM, AM/RM and audio rate modulation.

For me, operating in a high-sampling-rate environment is akin to adding another color or tone to the sound designer’s palette, like various types of FM - it’s just another tool in arsenal to create the desired timbre.

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well, good that you push things that far then :slight_smile:

I had the nanV output of Tangents at 48kHz

I did have a NaN case when Opulus was just out (long since fixed), but Tangents still refuses here :wink: but maybe I just haven’t pushed it far enough

you must try harder!!!

I also test at that rate, usually so the perf meters work better. I wrote an article on that a few years ago.