Zebra 3 Teething Troubles

[eclipse_soundlab]

not a big bug, but still reporting.

[Chris-S]

When loading the attached preset which I created and playing E above middle C (E3) I'm getting a horrible oscillating ringing noise in the background. I've done the same set-up in Serum and Pigments and it's not occurring. Is this normal? https://www.transfernow.net/dl/202604233QYGLbp6

You get this only on this one note (E3)?
The ringing which I see in the output is coming from the band-limiting, I guess.

Screenshot 2026-04-24 212107.png

[eclipse_soundlab]

Removing mod assignments in modmatrix (x button) changes the mod amounts for other assignments in the patch on random.

It can also change (temporary - it will reset on next (any) mod assignment) mod connections.
example - when i drag little mod-cob on filter 1 (Picture 1) - comb1 ratio mod amount is moving in the mod matrix (Picture 2)

[tasmaniandevil]

Removing mod assignments in modmatrix (x button) changes the mod amounts for other assignments in the patch on random.

It can also change (temporary - it will reset on next (any) mod assignment) mod connections.
example - when i drag little mod-cob on filter 1 (Picture 1) - comb1 ratio mod amount is moving in the mod matrix (Picture 2)

* Which operating system?
* Which host (DAW)?
* Which plugin format (VST3, CLAP, AU, AAX)?
* Can you share a preset example?

[Funkybot's Evil Twin]

Yeah, I should have mentioned this. We hide them by default because they annoyed some people.

One area where I think the Tentacles can be improved in the future: currently, they only show modulations that are visible on screen, meaning if they're modulating something that's scrolled down, you don't have any idea. Example: E3 is modulating Filter 3, and Filter 3 is scrolled out of sight. How do I find out what it's modulating? What tells me to scroll?

Not sure what the right answer is, but maybe the tentacles could point to the scroll bar.

[Urs]

Yeah, I should have mentioned this. We hide them by default because they annoyed some people.

One area where I think the Tentacles can be improved in the future: currently, they only show modulations that are visible on screen, meaning if they're modulating something that's scrolled down, you don't have any idea. Example: E3 is modulating Filter 3, and Filter 3 is scrolled out of sight. How do I find out what it's modulating? What tells me to scroll?

Not sure what the right answer is, but maybe the tentacles could point to the scroll bar.

Funnily, there's supposed to be an arrow on the scrollbar pointing to the right direction... but it seems to be gone... I must have added a bug shortly before the release, so I didn't catch it...

[Funkybot's Evil Twin]

Hey, look! I found a bug!

An arrow on the scrollbar is indeed a great solution.

[tumface]

Possible redundant stuff in the manual, page 28:

Offset

Only available if the Renderer is set to Wavetable. Bipolar phase shift, -180° to +180°. For a static offset, use Constant as source in the modulation matrix.

The Z3 final release has a dedicated knob for a constant phase offset, so I think the instructions to use a constant assignment via the mod matrix aren't needed anymore, right?

[Urs]

true

[Funkybot's Evil Twin]

Would it be good or bad UI if each of the generator/modulator panels could be minimized/expanded to avoid/limit scrolling when not desired?

Part of me wouldn't hate a list of generators/modulators that I could expand to edit. If minimized, the tentacles or highlight options could then just highlight the modules where the modulation is occuring, if visible, same as today.

Just a random thought I haven't vetted too deeply but I see some appeal in. I think every DAW lets you minimize/expand the track control panels in the arrange view, so the concept shouldn't be unfamiliar to plugin users. This would be kind of similar. Minimize what you don't need to focus on, while still having an overview of everything, expand to edit.

[Urs]

Would it be good or bad UI if each of the generator/modulator panels could be minimized/expanded to avoid/limit scrolling when not desired?

Thought about this a lot, but we decided that using the Groups feature is best for now, because we do not need to add a bar to the modules to make them collapsible.

[Funky40]

My one question for those of you running into CPU limits is did you try lowering the buffer settings? With the introduction of Efficiency cores you can run into situations with DAWs that allow the use of them where it defaults to e cores and does not shift to Performance cores because that function is supposed to be controlled by the OS, and the OS doesn't care about audio quality.

Counterintuitively lowering the buffer settings can force the OS to allocate tracks to p cores, maybe solving your CPU issues until Z3 gets multicore support. The other one is DO NOT use the Yellow filter for polyphonic work unless you like CPU overloads! I ran into that right away until Urs pointed that out, because I prefer it, and it's a ridiculously CPU piggish filter designed for sound over CPU.

Thats interesting what you are saying.

vs. high CPU load, especially vs. M4macs

I had any apple silicon Mac Desktop CPU.
My observation vs. "live-playing" was this:
a buffer size of 64-128 samples is what the CPU likes the most.
128 samples seems the best compromise for a starter setting

To make it bigger can worsen the CPU load.(it usually does. Thats using Gigperformer as my host. And its % read out)
There are more factors involved here. For example can single plugins require to have a higher buffer setting -vs. live playing usages- . (has much likely a relation to my next point)

My point to be made:
In general was my observation that a M4 CPU is crackling much faster than a M2 CPU compared to the shown CPU load in %. And more plugins seem to be prone to force the M4 CPU into crackling (this one is vs. FX in my case)


Vs. the "high CPU consumption presets" of Zebra3:
- it started to bother me. So i started to go thru ALL presets and just rename them
- i just add a "CPU" or "CPU!!" mark into the name. In front, or at the end.
- This helps alots !....i nolonger have to be surprised, haha

I could imagine that it would be a good idea if U-He themself would add such a mark into the preset name....??

I agree, some of these "high CPU load" presets are even not anything special sounding. Some even not exactly good. Anyway, ...taste, ...and "choices".

But i think U-He themself should add a "CPU" mark tag where due.*
At least i can`t remember these preset names and would run again and again into same...."oh look mom, a Zebra that can eat a top of the line Mac CPU".....case

* and just be so "unrespectful" to the sound designer in charge

personally, i take the renaming scheme much further. creating a listing scheme based on using alphabetical rules. (which is of course a personal thing, and can`t be donne by the devs )


but then, "if i" was U-He i would be so rude and just add also a "z_" or "zz_" or "zzz_" in front of the name with some of these CPU hogs. i think it would save some G.....uhm some CPUs..... some tears

[joradn]

Sometimes using modal profiles with too many modes (>256) will crash the audio engine. I haven't found a way to reliably reproduce it, but it tends to happen when loading the profile, or activating a modal module with it already loaded. Of course, it's easy to fix the broken profiles but I figure it's worth reporting anyway.

[machinesworking]

My one question for those of you running into CPU limits is did you try lowering the buffer settings? With the introduction of Efficiency cores you can run into situations with DAWs that allow the use of them where it defaults to e cores and does not shift to Performance cores because that function is supposed to be controlled by the OS, and the OS doesn't care about audio quality.

Counterintuitively lowering the buffer settings can force the OS to allocate tracks to p cores, maybe solving your CPU issues until Z3 gets multicore support. The other one is DO NOT use the Yellow filter for polyphonic work unless you like CPU overloads! I ran into that right away until Urs pointed that out, because I prefer it, and it's a ridiculously CPU piggish filter designed for sound over CPU.

Thats interesting what you are saying.

vs. high CPU load, especially vs. M4macs

I had any apple silicon Mac Desktop CPU.
My observation vs. "live-playing" was this:
a buffer size of 64-128 samples is what the CPU likes the most.
128 samples seems the best compromise for a starter setting

To make it bigger can worsen the CPU load.(it usually does. Thats using Gigperformer as my host. And its % read out)
There are more factors involved here. For example can single plugins require to have a higher buffer setting -vs. live playing usages- . (has much likely a relation to my next point)

My point to be made:
In general was my observation that a M4 CPU is crackling much faster than a M2 CPU compared to the shown CPU load in %. And more plugins seem to be prone to force the M4 CPU into crackling (this one is vs. FX in my case)


Vs. the "high CPU consumption presets" of Zebra3:
- it started to bother me. So i started to go thru ALL presets and just rename them
- i just add a "CPU" or "CPU!!" mark into the name. In front, or at the end.
- This helps alots !....i nolonger have to be surprised, haha

I could imagine that it would be a good idea if U-He themself would add such a mark into the preset name....??

I agree, some of these "high CPU load" presets are even not anything special sounding. Some even not exactly good. Anyway, ...taste, ...and "choices".

But i think U-He themself should add a "CPU" mark tag where due.*
At least i can`t remember these preset names and would run again and again into same...."oh look mom, a Zebra that can eat a top of the line Mac CPU".....case

* and just be so "unrespectful" to the sound designer in charge

personally, i take the renaming scheme much further. creating a listing scheme based on using alphabetical rules. (which is of course a personal thing, and can`t be donne by the devs )


but then, "if i" was U-He i would be so rude and just add also a "z_" or "zz_" or "zzz_" in front of the name with some of these CPU hogs. i think it would save some G.....uhm some CPUs..... some tears

So instead of going down that rabbit hole of renaming I would suggest a few things right away, because in no way should an M4 perform worse than an M2, and that makes me think even more your issue is the DAW and OS not communicating well and your track getting stuck on efficiency cores.

First off open Activity Monitor and CPU Usage and CPU History windows. Usage shows when a core overloads quickly and the History shows the names so you can see if efficiency cores are overloading.

This way you can figure out how to get the tracks on performance cores, because I'm betting that's your issue, I don't even have issues with Zebra 3 on an M1 Macbook Air. The only time I've overloaded the CPU is by making a patch with the Yello filter, which is best for monophonic sounds etc.

[tumface]

You might have a hard time spotting the problem in Activity Monitor, because the audio processing threads might be rapidly switching between performance and efficiency cores. A DAW on an Apple Silicon Mac needs to use the thread workgroups API to associate the audio processing threads with the audio device, which makes the OS allocate the audio processing threads onto performance cores, even if they're currently not using much CPU. Otherwise, the audio processing threads will be swapped back and forth between efficiency and performance cores, depending on how much CPU load they're causing.

So, let's say you have a VST instrument that's sitting idle and barely doing anything, because it's not having any notes played into it. The thread it's on, owned by the DAW, might be sent to an efficiency core by the OS. Then, you throw both hands onto your MIDI keyboard and play 8 notes at once, the CPU usage from the VST instruments spikes because it's now synthesizing 8 voices at once, up from 0 voices, and the OS decides to move that thread onto a performance core.

Moving the thread takes time and stalls for a moment, so you get an audio dropout. Then, after you stop playing the notes, the OS notices the thread isn't doing much anymore, and moves it back to an efficiency core to save power. Repeat over and over again. Low CPU usage in Activity Monitor, and you see performance and efficiency cores being used, but you keep getting dropouts for no apparent reason. The DAW has to solve this problem. Plugins can't do much about it.

By the way, if it's implemented properly, setting an artificially low buffer size in the DAW shouldn't be necessary.