Swankyamp 1.2 starts sounding like a tremolo over time

[38github]

Reaper 6.14 amd64
SwankyAmp 1.2 vst3
48000 Hz

Played guitar for about two hours and thought the sound was weird and it kept getting more and more intense over time.

Audio sample: https://voca.ro/lakD2uOceku

[gmcgoldr]

This is a strange one. I can't reproduce it on my system in Swanky Amp 1.3.1 (Intel CPU). If more users encounter the issue and report I will hopefully be able to start narrowing it down.

If anyone is able to reproduce the issue, please post here and consider answering any questions you can from the following list:

• what version of Swanky Amp, OS, DAW / host are you using
• what kind of CPU do you have
• how long before you start noticing the issue
• was the plug-in idle for a long period of time (i.e. guitar plugged in but not actively being played)
• does this happen with different parameter configurations
• if you stop (but don't close) the track, and then resume, does the issue persist
• if you disable the plugin and then re-enable does the issue persist
• does the issue arise for any hardware / capture device

[KottV]

@38github
What the audio subsystem is (ALSA, JACK) ?
Is it SwankyAmp definitely wrecks the sound? I mean, what if you bypass the plugin or route signal to the other track/fx?

[38github]

• OpenSUSE Tumbleweed x86_64, Reaper 6.14, ALSA, Swanky 1.2.0 VST3
• Intel Q9550
• Occured after probably 1½ hours of use.
• It was maybe idle for a couple of minutes while I had a smoke
• Not sure if it happens with different parameters.
• I recorded and played back the sound and the plugin continued to sound degraded after that.
• I didn't try to disable and then enable the plugin, only changed Reaper's wet/dry knob to hear the dry signal which was not affected.
• It does not arise from the capture device since the dry signal was unaffected.

[gmcgoldr]

Thanks for the info. Does the sound quality change in any way other than the trem? The audio clip sounds very thin to me, is that just how you setup the amp or is that part of the issue that it thins out the sound?

I got a pointer that this could be related to buffer issues, and that could be related to how Linux audio stack is calling the processing function. It's all just hunches right now. I'll have to look at the Linux compilation script. For reference I just ran the plugin overnight and found no degradation on my system, so I think it's quite conclusive that this bug affects not all systems. I will try it out with reaper on Windows to further try to isolate the issue.

Again, if anyone is experiencing this on different platforms please leave a comment.

[38github]

I have now started a test that will go on for maybe two hours (a looped sample) but this time using Pulseaudio, SwankyAmp 1.3.0 and the built in sound card of the motherboard.. At the end I will disable the plugin and enable it again to see if the tremolo sound goes away. I will get back to you when it is done.

[38github]

The test is finished now and no weird tremolo effect occured within two hours of use. This time around thought I used among several things (Pulseaudio, built in sound card) version 1.3.0 instead of 1.2.0.

[gmcgoldr]

Ok, well that's mixed news. It sounds like it's some kind of configuration problem. Could be something in the software that's not playing nice with the way the VST APIs are called in the Linux build, could be something about the Linux build process (if the wrong flags are used it could cause issues, but given that you got it working in a different situation makes that less likely). Or maybe it was something really intermittent.

If you keep using the plugin and get the issue again, I would appreciate if you leave a comment here to describe your setup (audio subsystem and soundcard). I'd like to get to the bottom of this. But it'll be a bit lower priority, and I might have to setup a Linux box for testing. Maybe I can find whoever is building the Linux packages and see if they have any ideas.

I guess pulseaudio with build in sound card has lots of latency and isn't usable? Please let me know if you find a configuration where you can use this reliably.

[38github]

I have now played with SwankAmp 1.3.1 for about three hours and now the tremolo effect has occured. Interesting thing is that the tremolo speed changes when adjusting the low pass in the Staging section.

https://vocaroo.com/msl2XBUkIrj

[gmcgoldr]

Version 1.4.0 includes fixes to things that could have caused this issue. If this doesn't address it then a deeper investigation of the Linux host environment will be needed, and/or looking into the Linux compilation optimizations.