• Registered: 2008-10-21
  • Posts: 57

Topic: Strange behavior in a Logic project with beta driver and UAD

(posted this as well in the UAD forums since I don't know where my issues come from)

Hi there,

after switching to a Mac Studio / Monterey and a UAD TB3 Quad, I started my first semi-big project in Logic.

For starters, I had switched latency to luxurious 64 samples with the RME Babyface Pro FS (beta driver for DriverKit, no kext), and everything worked fine until the aforementioned project:

I use a mix of hardware and software synths. As soon as I start using UAD plug-ins, I start having issues, but only at the very beginning and the very end of the project: heavy dropouts, lagging GUI, CPU meters in Logic go through the roof - but ONLY in the intro and outro sections of the project where my Bass Station II plays a simple line with some UAD Lexicon reverb added. After the intro, the Bass Station + reverb just plays on (!), all the other synths and FX set in, and CPU goes way down to about 25% on all cores. So, it works normally when MORE power is needed and used. During the outro, it's the same: the software synths play less and less until only the Bass Station plays its line solo - and the CPU kills itself again.

Workaround: setting Logic to 128 samples which is fine but strange nonetheless.

Any ideas what's going on here? Again, the Bass Station + Lexicon hardly ever stops, the issues however stop with MORE CPU tasks during the project and set back in when going solo again.

2 Reply by ramses (edited by ramses 2022-08-01 10:23:26)

  • ramses
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Re: Strange behavior in a Logic project with beta driver and UAD

How is it working without using UAD VST plugins? Simply the audio workload of Logic and the VSTi(s)?

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
  • Registered: 2008-10-21
  • Posts: 57

Re: Strange behavior in a Logic project with beta driver and UAD

When I turn off the UAD reverb in Bus 1 (which is being sent signals during intro AND all the rest), the CPU meter drops immediately to something measly I have never seen before on my 10 year old iMac i7. wink Okay, so it seems to be the UAD driver which won't handle 64 samples of latency too well. However, why does it recover AFTER the sparse intro when ALL the soft synths set in and the load is much higher? No issues whatsoever, although the same Bass Station sound still feeds Bus 1. Really strange...

4 Reply by ramses (edited by ramses 2022-08-01 10:19:26)

  • ramses
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Re: Strange behavior in a Logic project with beta driver and UAD

When I tried the UAD Octo card, I also had strange side effects and only one buffer size was really stable, I had to send it back.
https://www.tonstudio-forum.de/blog/ent … cie-en-de/

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
  • Registered: 2008-10-21
  • Posts: 57

Re: Strange behavior in a Logic project with beta driver and UAD

Never had any problems. Had UAD-1 and UAD-2 PCI and UAD 2 FireWire, now TB3 - always on a Mac, never any issues. I can live with 128 samples, I was just wondering why it happens this way - 95% of the song work fine, and in the most harmless sections, I get the spikes.

6 Reply by ramses (edited by ramses 2022-08-01 10:52:43)

  • ramses
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Re: Strange behavior in a Logic project with beta driver and UAD

> always on a Mac

Thought already that in my case it might have to do that UAD has its root in the Apple universe, PC came later.
Regarding spikes … any background services on your apple that might disturb when using UAD?
Can you try a different DAW? Maybe Cubase or Reaper?

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
  • Registered: 2008-10-21
  • Posts: 57

Re: Strange behavior in a Logic project with beta driver and UAD

Nah, nothing here to test. The spikes are reproducibly connected with the song sections. They start as soon as the Bass Station plays its intro tune (with one send to Bus 1 / UAD reverb) and end, as soon as quite a few soft synths start playing along. The Bass Station goes on, always using UAD FX, so the CPU load gets heavier and heavier after the intro, while the spikes and dropouts stop. Really strange.

Again, when fewer and fewer soft synths play towards the end of the song, suddenly the spikes come back in. This happens with or without all the other apps that are usually running (Mail, Safari, Things, all native).

The only way to circumvent these spikes is to deactivate the UAD reverb in the Bus 1 channel or to set the latency to 128 samples. With the latter, I can live. I'm just wondering what's going on here. And what happens, when I use more and more UAD plug-ins or start other projects with an even heavier UAD load. I don't want to switch to 256 samples just to please my UAD...