ZynAddSubFX troubleshooting presets

Builded in yocto with following recipe I’ve found some presets to be unusable (= high cpu, xruns). Try for example:

  • net-wisdom: 0086 - Cindi - B (is that you Cyndi?)
  • net-wisdom: 0087 - Cindi - C

I just would like to know if users here experience the very same issue. If yes, would be good enough to understand which “functionalities” of ZynAddSubFX triggers this behaviour. Like heavy fftw stuff for example. Maybe the patches could be reworked: I don’t think this can be done on the Duo (unsure) since on mod ui I only see below interface (which I don’t know how it can be used)



I’ve found the current build of zyn to be quite unstable on the 1.12 rc firmware, but haven’t delved too deeply into troubleshooting yet. I may try to help when I have time.

Prior to upgrading to the beta firmware I was able to load the plugin and cycle through some of the presets, but yes I did see similar crashing behavior to what you mention.


the zynaddsubfx version on the (beta) store is old now, was a test to try to get the full synth working for MOD with hacky patching to reduce dsp load at the cost of sound quality.
but that was back on Duo days.

being unstable is expected, one of the reasons it is still in beta.
we need to update to latest upstream stable release, and refresh the patches as needed (some have been applied upstream)
there is no point testing the current beta build.


Just to clarify I have tested ZynAddSubFX 3.0.5 (see patches applied on link above) and I see latest upstream is 3.0.6. I’ve seen 3.0.5 was released in 2019, while 3.0.6 is january 2022.

Right, but that is with yoccto and custom recipes. MOD is never going to officially support these.
If you build it with mod-plugin-builder, we can talk about details and tweaks.

At least on buildroot, we can force specific optimization flags on a per-platform basis.
The MOD builds rely on this in order to get proper optimized binaries.

In any case, we need to update/refresh the patches against 3.0.6, or even latest git as there have been a few substantial fixes since 3.0.6.

We can set flags per platform in Yocto too. Regarding Mod support this is up to you, I don’t expect this to happen. This yocto layer is currently WIP and can’t replace mod-plugin-builder right now, but majority of stuff is there.

Regarding ZynAddSubFX in the yocto recipe is the same of mod-plugin-builder referenced by v0.8. Also the patches are the same, this is intended to keep aligned with mod. I expect them to be at least equivalent. I welcome the suggestion to update to latest git commits, I’m not sure when I will be able to work on it, but definitely the resulting work will be shared.

Thanks & Bests

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