(question) Click/Pops When Connecting Audio Cables

(This might be common knowledge but I’m a beginner)

Does anyone know if Rack is supposed to make a popping sound when clicking on/moving a cable that actively has audio running through it? For example, if I have a VCO going straight to my audio-8 module and I switch the oscillator type from sine to triangle, a loud popping sound will occur the moment I click on the cable. The same thing happens when clicking on the cable at the other end. The pop also occurs if audio is being played back and I close VCV Rack.

edit: I’m on Windows btw and here’s a video of what’s happening: VCV Rack Pops/Clicks Example - YouTube

I’m using an external audio interface (ssl 2+) and have the sample rates matched at 48 kHz. Block size is currently 512, threads set to 8. I’m using a discrete graphics card. The problem occurs whether I’m using ASIO or WASAPI

I’m wondering if this is just a feature, as I can’t find an example online of someone switching the audio cable before turning down the VCA volume first. Do I just have to do that every time if I want to avoid the clicks/pops?

I would say it’s not uncommon. I don’t think the audio module has any particular anti-pop measures implemented, those things are implemented in e.g. the good mixers. So yeah, just something to be aware of, just like when plugging/unplugging cables into physical amps and speakers.

A tip. Keep threads set to 1 until you need more CPU, then increase to 2 etc. There is an overhead to multithreading so don’t use it unless / until you need to.


I’m not sure this is what you are experiencing, but when I click on an output port, the signal is cut until I release the mouse click. This can introduce some popping, even though this behavior seems to be designed to prevent pops, perhaps. This seems to be default behavior in Rack V2, at least for me with Windows.

It is common for modules to output DC as well as the desired audio. imao modules should not do this, as the pops you describe are just one of the bad side effects. It’s quite easy to tests for this - just run the audio into a spectrum analyzer and look for the telltale lump all the way on the left. In an extreme case you can see it on the scope.

Even with no DC, patching and switching may induce less bad pops and clicks.

If you are using a module that does this, you can probably find an alternative that works properly, or the developer may fix it if you report it as a bug.

Here is a case that is both typical and extreme - the pulse output of a VCO:


I see; thanks for the response. I tried it out with a Mixmaster and I’m experiencing the same thing. I edited my post to include an example I uploaded.

Thanks, I’ll keep that in mind. The example I uploaded is with threads set to 2

Please note, adding or removing cables needs thread synchronization in Rack‘s engine. Depending on your system performance, the audio buffer settings or your audio driver this can also cause clicks.

Thanks for the response - I edited my post to include an example video. I’m using the stock VCO. As for sending the pulse output to an analyzer, does that mean simply connecting the SQR output on the stock VCO to the analyzer - or do I have to trigger it somehow to replicate your example? If it’s the former then I’m not getting the same lump shown in your screenshot

Yeah, stock VCO doesn’t have that problem, afaik. So maybe it’s not what I was talking about. In my image, that wasn’t connect disconnect, That was just steady state.

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Yeah, you’re having a bad case of it, I can see/hear in the video clearly. But again, nothing to be directly alarmed about unless you need to do it during a live performance, then you’ll need to do something.

Try and right-click on the “MASTER” label on the mixer, and verify that “DC blocker” is turned on. Likewise, try and right-click on the audio module and verify that “DC blocker” is turned on and that “Master audio module” is turned on. After that, try and set Threads=1 in the Rack “Engine” menu. If none of that helps I have another trick you can try…

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Is it reasonable to think that anything can prevent the click or pop associated with clicking on an audio cable end? I’ve run through everything I can change and nothing changes the behavior, at least in Windows.

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i’m not sure it is. We can add anti-pop to controls within our modules, but a cable disconnection happens outside the module and potentially involves a rapid change in voltage that produces the click/pop. I’d guess any code to prevent this would need to happen within Rack itself.


I really have never been bothered by the click, but I do not perform live nor patch during recording. Personally, in the live case, I would mute the mixer output, but this may not be possible in the middle of a performance. It might be possible to use a switch to switch between cable patches, but I have not tried that and don’t know what might happen.

Actually, an A/B->1 switch can switch audio patches without inducing a click.

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some switches have anti-pop some don’t sometimes whey they do, ppl don’t like it.

It seem that if VCV turns off the sound when you touch a cable or patch it, then it would be super cool it there were a feature to ramp this up and down so pops wouldn’t get generated.

I tested the AS A/B/Y switch and got no clicks or pops by clicking on the switch button or by sending a CV EXT signal.

My intent was to find one solution for the OP.

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I didn’t see until your latest post which switch it was that you were talking about. Interesting about AS - afaik after all these years their mixer doesn’t have anti-pop.

I have confirmed that some other switches do click and pop, but, the AS A/B/Y switch does not. I guess I got lucky and hit one that did not pop on my first test.

Edit: The AS A/B/Y module is proprietary, so we cannot look at the source code to see if it has click mitigation code.

I went through a lot of A/B/Y switches and did not find another one that does not have clicks and pops. So, the AS A/B/Y module is commercial module, but seems to have some magic.

If anyone knows of a free A/B/Y audio switch that has pop mitigation, let us know.