Strange audio artifacts in GxBoss DS1 LV2 plugin in Ardour

[btrummer]

Hi.

Some info about my system first:

• My PC is a Ryzen 1700, 32GB RAM
• Operating system is KDE neon (more or less based on Ubuntu 22.04)
• Ardour: 1:6.9.0+ds0-1build1
• Guitarix: 0.44.1+dfsg1-1 (I manually updated the guitarix packages because of the tube/cabinet selection bug present in 0.42.1, which is originally shipped with Ubuntu 22.04)

To reproduce, I was able to create a minimalistic Ardour workspace with the following setup:

• 96k sampling rate
• one mono track with a DI guitar recording and the GxBoss DS1 plugin, nothing else. Also the Jack input is not connected, so no noise is coming in from there.
• another mono track hooked up to the output of the first one, so I can capture the actual wave output and have proof of the artifacts in question. :-)
• start a playback and let the recording run some seconds over the ending of the original guitar region

What I get and hear is:

• most of the times, I get a strange distorted scratching noise which starts and ends again within a second after the playback / region end.
• sometimes I also get a constant beeping tone after that, which remains until I start a playback again.
• if this occurs, pressing the On/off switch within the plugin doesn't do anything. Only bypassing the whole plugin will stop the beeping.

I attached a ZIP of this Ardour workspace, so you can look/hear for it yourselves:
GxBossDS1Test.zip

Thanks and best regards.

[brummer10]

Hi Bernhard
Strange. I can't reproduce it here. I give your session a shot and it works here as expected.
Still, I'm using ardour Ardour7.2.0~ds0 on debian/sid with 96kHz/512
and I've updated the faust generated files to newer faust version 2.54.9.
When I remember right Guitarix 0.44.1 using faust 2.40.0 so that may differ from the experience.
Strange is, the GxBossDS1 run internal anyway on 96kHz so issues may be expected at 44.1kHz but not at 96kHz.
regards
hermann

[btrummer]

Hi, thanks for trying out.

In the meantime I found out that I hear exactly the same issue on my laptop machine, which on the other hand didn't really surprise me, because I use exactly the same software versions there than on my PC (in order to keep my projects easily interchangeable).

I also listened more closely to some other Guitarix plugins and how they behave after a playback region ends. I found out:

• GxTubeScreamer => sounds ok
• GxScreamingBird => sounds ok
• Gx Studio Preamp Mono => sounds ok
• GxHogsFoot => sounds ok
• GxMXR Distortion => sounds ok
• GxAmplifier-X => sounds ok
• GxCabinet => sounds ok
• GxRat => sounds ok, but some DC offset stays on the output after the region ends (the spectrum analyzer of the LSP Parametric EQ shows it as around +12dB when having a shift of 40dB)
• GxMetalHead => sounds just awful, like a very distorted hum and scratching noise is overlaying the signal
• GxMetalAmp => same awful hum and noise, just the tone of the "supposed-to-be" signal sounds different (which I guess is expected in this case)
• GxRedeye Chump => same, but the hum and scratching sounds even worse than with the GxMetals
• Gx w20 => sounds ok

Maybe the GxMetals and GxRedeye Chumps have something in common that doesn't behave as it should on my machine.
I could also check on an older PC (running Debian bullseye) tomorrow...

PS: if you want to reject this issue (because of not being able to reproduce), then I'd understand and be fine with that.
My "workaround" for the near future is: don't use these "bad" plugins (well, "bad" for me, not "bad" in general I assume).

Thanks.

[brummer10]

Thanks for reporting, I'll keep it open as a reminder for me to do some deeper checks.
To the GxMetals, I play for some time with the idea to remove them from the package, as those have indeed serious issues. They are only there because I would avoid to destroy "someone's workflow". But I guess it will be better to remove them before the next release, as properly no one use them seriously.
regards
hermann

[btrummer]

Hi.

FYI: I can reproduce the original issue with the GxBoss DS1 plugin on Debian bullseye (/etc/debian_version == 11.6), where I just updated all installed packages to the latest versions (including reboot):

• PC: it's an old Intel core i3, but fast enough to playback the previously attached Ardour project. :-)
• Ardour: 1:6.5.0+ds0-1
• guitarix: 0.42.1+dfsg1-2

Like on my two "modern" machines:

• I almost always hear the mentioned one-time scratching noise after the region or playback ends.
• The continuous beeping noise does not always appear. I have to playback/stop up to 10 times until it appears, but then it stays audible even if the playback is stopped.

Thanks and regards.