JCM800 dying in a static noise at 96khz

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JCM800 dying in a static noise at 96khz

Postby gimmeapill » Thu Feb 09, 2017 8:31 am

Hello Hermann,

I have a few stability issues with the JCM800 at 96khz but unfortunately very little info for troubleshooting. Sometimes it works ok for an hour, sometimes it dies with an ugly noise after a few seconds or just a few minutes.
This has been happening for at least a few months (probably since 0.35). I didn't report it before as I'm not using it that much and I was trying to find a pattern, but there's no particular error message, no xrun in jack, etc...
The only hint is that it always happen when I'm running jack at 96khz.
Do I have to build with a debug flag to get something more meaningful?
Last edited by gimmeapill on Thu Mar 09, 2017 10:21 pm, edited 2 times in total.
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Re: JCM800 dying in a static noise at 96khz

Postby brummer10 » Thu Feb 09, 2017 10:25 am

Hi

Did it happen with the LV2 version, or with the guitarix internal plug? Or with both versions?
Internal both running at 96khz anyway, so my first guess will be the implementation of the resampler. Just turn it of when 96khz detected may help, if it is the internal version which makes the trouble.
For this case a debug-build wont really help, but I could check if I've changed anything related in this plug over the last year.

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hermann
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Re: JCM800 dying in a static noise at 96khz

Postby gimmeapill » Thu Feb 09, 2017 11:21 am

Hi Hermann,

That's the guitarix internal module. I didn't notice any issue with the LV2 version the 1 or 2 times I tried it, but I didn't use it extensively either.
Also, I can't tell for sure if the issue is really related to the sampling frequency. I'm using 44.1k briefly for testing stuff, but I usually play at 96k. So it's entirely possible that I missed it.
I just assumed that if the issue was present at 44.1khz, more people would have reported the problem.
I'll try to let the LV2 version run for a while in a DAW at 96K, see how it behaves, and confirm back.

BR,

LX
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Re: JCM800 dying in a static noise at 96khz

Postby gimmeapill » Thu Feb 09, 2017 9:49 pm

The LV2 doesn't seem to crash in Qtractor, but I found a few others issues on the way. Some more reports to come ;-)
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Re: JCM800 dying in a static noise at 96khz

Postby brummer10 » Sat Feb 11, 2017 8:20 am

gimmeapill wrote:That's the guitarix internal module.


Okay, I've tried something ( switch off resampler when running at 96khz), hopefully it solves the issue.
Could you try it out?

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hermann
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Re: JCM800 dying in a static noise at 96khz

Postby gimmeapill » Tue Feb 14, 2017 9:28 am

It's better ;-)
I'm not 100% sure about the stability yet, at least it didn't crash in ~30mins of testing.
But I'd swear the sound of the JCM800 is even more impressive now. It really has that creamy feeling you get with premium NOS tubes. CPU usage might be a bit north (although I'm not 100% sure about that), but who cares, that one is really a winner.

BR,

LX
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Re: JCM800 dying in a static noise at 96khz

Postby gimmeapill » Wed Mar 08, 2017 9:53 am

Didn't have any more stability issue, marking this one as fixed.

Thanks Hermann!
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Re: [Solved] JCM800 dying in a static noise at 96khz

Postby gimmeapill » Thu Mar 09, 2017 10:20 pm

...And I spoke too fast. the JCM800 died again after playing for a good 10minutes with a static noise and a flock of xruns. Didn''t come back until I restarted Guitarix, so it looks like the same issue...
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Re: JCM800 dying in a static noise at 96khz

Postby gimmeapill » Wed Jun 21, 2017 10:12 am

Just to confirm: the JCM800 is still going to hell after a few minutes @96K (as of latest git).
I'm not particularly impacted as I have reverted to 44.1Khz: there's not much of a sound difference anymore.
So running guitarix at 96K is just not worth the extra pain.
But maybe this one would be a good candidate for the down sampling treatment?
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Re: JCM800 dying in a static noise at 96khz

Postby brummer10 » Wed Jun 21, 2017 1:43 pm

mmm, the nonlinear part of the jcm800 simulation runs internal at 96kHz, regardless of the chosen SampleRate.

So the culprit should be in the linear part, indeed I could wrap a SampleRate guard around that part.
I'll post here when done, but properly it takes some weeks before I found time for it.

Thanks for reporting the issue and help to make guitarix even better. :metal2:

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