Rack 2 Pro crackling?

I’m running a more than sufficient system that was loving Rack 2 up until today. Patches load much slower than earlier this week, as does the browser (nothing new there), and all of my patches I’ve made from the last week or so have a fuzzy, crackling quality to them, like my CPU can’t keep up, or there’s a wiring problem with my speakers. I checked other audio, no problems there. I uninstalled VCV and reinstalled, that didn’t help. I checked Task Manager while running Rack to see if there was a strain, I was humming at about 3%. I’m running a 12-core AMD with 64gb of DDR4 RAM, on a 1tb Evo970 M2 drive, through a UMC404HD interface. As I’ve said, this system has had 0 problems up until now. Anyone else seeing/hearing anything like this? Help!

I should mention, I’ve checked my levels and nothing is spiking.

You’ve not accidentally changed your sample rate? Maybe caught the menu by accident.

nope, checked that as well funny story though I just ran Windows update, there was one waiting All is fine now stupid PCs

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In case anyone else comes here searching for a similar topic, I also get audio crackling when running VCV Rack 2.

I’m using a MacMini running macOs v12.6 with 3GHz Intel 6-Core, 8GB Ram and VCV Rack v2.1.2

After reading the manual on performance tuning, I tried adjusting the thread count. The manual suggests increasing the thread count for better performance, however I only seem to be able to get rid of the audio crackling by selecting one thread only. My VCV Rack 2 CPU usage rarely goes above 25%, so I find it strange that this is necessary!

Does anyone else have this problem as well?

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Have you tried bumping up the “Block size” in the VCV AUDIO module?

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@john_rose ah yes, that does the trick! I can run with multiple threads without crackling now, many thanks :slight_smile:

BTW Start with one thread and when the crackling starts, add another. Don’t start with as many threads as you can. And indeed try different block-sizes.


Well, that’s good news. :tada:

I picked a block size of 512 and did a Preset > Save default so I wouldn’t forget it for new patches.

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It’s crazy. I always had a lot of glitches when playing with VCV Rack 2 (Apple M1 Max). I could never fix it until today. I got into more advanced software development as of late, and that gave me an idea. What If it has something to do with multithreaded behavior? Indeed, if I lower the number of threads used, glitches go away! 1 thread sounds hugely better.

Some extra info. When I use the recorder module in video output mode, everything slows down and glitches like hell but the output videos aren’t corrupted, and the audio sounds fine.

Is there any explanation for this and hopefully a fix?

From the VCV manual:

Audio/video recording:

Use VCV Recorder to record audio or video. Unlike non-Rack-specific screen recording software, it operates in Rack engine “time”, not real-time, and therefore does not record real-time audio hiccups/stuttering. This means that any hiccups/stuttering you hear in real-time will not be present when the recording is played back.

I’m sorry Auret, but what does it have to do with one threaded mode not having glitches compared to multithreaded mode?

I want Rack to be playable as an instrument.

Your question was a little confusing ?

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Yep. I guess it was. Thanks for the answer!

you asked two or three questions, he only answered one.

Everyone says this so it must be true. I have to say most other multi-threaded software I use “just works”, and you don’t have to set all this thread stuff by hand.

Also - so many reports recently what just two threads makes crackle city - did something regress? Or just hearing more reports…

Another report here of lots of glitching on the M1 Max. Works great on a single thread, but I haven’t been able to get a usable result above that. It’s led to some interesting creativity with my patches to keep CPU usage within the capabilities of a single core, but I’m finding it quite limiting overall.

I’ve been in touch with VCV support and I know they’re working on it. If you’re having similar issues, I’d recommend sending them a quick email so they can get a few more data points.