Master volume difference between 44.1kz and 96khz

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Master volume difference between 44.1kz and 96khz

Postby gimmeapill » Fri Jan 06, 2017 12:51 pm

Hi Hermann,

I've recently done some A/B tests between 44.1 and 96k, and I noticed that there's a good 10-15db difference in Guitarix standalone depending on the sampling frequency.

In short: presets made at 44.1k sounds awfully loud and distorted at 96K, and the ones made at 96K are way too quiet. At 96k, the Master volume needs to be rolled back to -20, -30db usually to avoid crackles.

I am not sure which individual modules are affected (I didn't measure the volume at every stage of the signal chain), but this seems to affect the Master in Guitarix standalone rather than the effects or LV2 plugins.
Not sure if that really qualifies as a defect, but ideally Guitarix presets should be portable between 44.1, 48 and 96k.

I'll upload a preset later today as I'm at work.

LX
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Re: Master volume difference between 44.1kz and 96khz

Postby gimmeapill » Sat Jan 07, 2017 5:56 pm

I tested a bit more and here's an example attached.
The preset Basic Metal contains only Guitarix amp + cab simulation.
When I switch from 96k to 44.1 I have to compensate on the master vol from -34 to -18db to get the same perceptible volume.

Jack settings:
Code: Select all
/usr/bin/jackd -P89 -p128 -t2000 -dalsa -r96000 -p64 -n3 -Xseq -D -Chw:USB -Phw:USB -i2 -o2
/usr/bin/jackd -P89 -p128 -t2000 -dalsa -r44100 -p64 -n3 -Xseq -D -Chw:USB -Phw:USB -i2 -o2


tested with guitarix-git-0.35.2.r23.g1287b0c8
Attachments
scratchpad.gx
Basic Metal Preset made at 96k
(38.21 KiB) Downloaded 11 times
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Re: Master volume difference between 44.1kz and 96khz

Postby brummer10 » Mon Jan 16, 2017 4:29 am

Hi

That is strange, indeed. The amp simulation run at 96khz internal anyway, so there should no difference in the output. The Master volume works independent from the sample rate, and the cabinet does resampling to the used sample rate, so there should be no difference also.
My soundcard didn't support 96khz, so I cant reproduce the issue here, are you able to reduce the used modules to find the one which case the issue?

regards
hermann
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Re: Master volume difference between 44.1kz and 96khz

Postby gimmeapill » Mon Jan 16, 2017 10:52 pm

OK, I found the culprit: it's the Presence control.
With only a master and everything on the default setting and Presence disabled, there's no volume difference between 44.100 and 96k.
Do the same with Presence set to max and it's louder at 96khz.
Actually, it's not only louder, it also sounds quite different - that's probably why I like much more the sound of guitarix at 96k (& I'm not so sure anymore if I would like that bug to be fixed ;-))
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Re: Master volume difference between 44.1kz and 96khz

Postby brummer10 » Wed Jan 18, 2017 4:56 am

I'll fix it asap, as soon I've a little time. :)
Maybe I set it to run at fixed 96khz internal like the tube emulations do, . . .
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Re: Master volume difference between 44.1kz and 96khz

Postby brummer10 » Fri Jan 20, 2017 8:22 am

So I've pushed a fix (hopefully) for this to git. The Presence unit now runs at 96khz internal. Could you please check if that fix the issue without disturb your experience at 96khz?

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Re: Master volume difference between 44.1kz and 96khz

Postby gimmeapill » Fri Jan 20, 2017 9:21 am

Ok, I'll rebuild and do an A/B comparison this WE.
Thanks!

LX
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Re: Master volume difference between 44.1kz and 96khz

Postby gimmeapill » Sat Jan 21, 2017 8:16 pm

Results of the tests as of 0.35.2.r26.g249cd194:

Presence sound at 96K is unchanged - good
But the last changes broke the Presence control at 44.100. It bails out with the following message:
Code: Select all
[20:54:27]  convolver  ***  error in Convproc::configure


and...I found another volume issue between 44.1k and 96k with the cab simulator:
with the 4x12 cab, eqs at noon and volume at 1, at 44.1k enabling the cab simulation lowers the overall volume.
At 96k the volume stays constant (subjectively). I didn't try yet other volume settings or cab simulations, but it looks like there's an issue either with the 4x12 IR or with the volume control.
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Re: Master volume difference between 44.1kz and 96khz

Postby brummer10 » Sun Jan 22, 2017 7:44 am

Thanks for testing, yes, this approve didn't work.
I'll try to fix it next week, I guess the culprit is in our ffmpeg convolver.
Will post here when I've done some work on it.

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hermann
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Re: Master volume difference between 44.1kz and 96khz

Postby brummer10 » Fri Jan 27, 2017 1:17 pm

So, hopefully fixed now.
Please re-try and let me know if it works now. If so, I could add this fix to the cabinet and amp-impulse plugin as well.

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