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Sample rates and resampling questions
androdion
post Nov 10 2012, 14:04
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Hi. I have a few questions which involve sample rates and resampling. I have a Xonar Essence STX as a sound card on my PC and I've been trying to learn a few more things about the best possible settings on its control panel. With that being said some doubts and questions have arisen, and the Internet is not being exactly friendly in my pursuit for a direct answer.

So my main question right now is if putting the sample rate on the Xonar control panel to 192Khz will make it resample any signal lower than that to 192Khz, or, if by putting the sample rate defined as 192Khz if it will reproduce every sound within that spectrum without resampling it.

For instance, I know that CD audio is 44Khz. Will it change the sound output in any way if I have the sample rate on the Xonar defined as 192Khz as opposed to 44Khz? This for a 2.1 system playing an audio CD. Does resampling to 192Khz occur in this situation or will the Xonar detect a sample rate within the available spectrum and play it accordingly? This is something that's been bugging me because everyone says that the sample rate on the Xonar should be set accordingly to the source of the sound (CD/DVD/whatever) but no one actually answers this simple question directly. Also, does the Windows 7 sample rate need to be set to any value or does the Xonar control panel override it? Having the option "Allow applications to take exclusive control of this device" selected means that I don't need to worry about which settings are defined on Windows?

One other thing, I've been reading that on the Mixer tab on the control panel 76% volume is the default for 0dB and that putting it any higher than that will cause a digital gain that could cause distortion. Is this true? Is there any difference between the 75 and 76% settings at all? Because strangely if I put it to 75 it will reset itself to 76, but if I choose a lower value (say 50%) it will be set as that.

And since we're on the Xonar subject I might as well ask. On the FlexBass tab, is there any threshold value to the LFE Crossover Frequency? What I mean is, is there any value here that's "too high" and should only be set up to a certain limit?

Thanks everyone for the patience and please help me out here. smile.gif
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dhromed
post Nov 10 2012, 14:58
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Disclaimer: I have a Xonar DG on XP. Your mileage may vary.

Yes, it will resample to the sample rate you specify. Whether this at all audible is another matter. I keep it at 44.1.

QUOTE
I've been reading that on the Mixer tab on the control panel 76% volume is the default for 0dB

The manual I've got says the exact opposite. The sliders operate on a percentage of full-scale, that is, 100 = 0dBFS.

The Xonar driver has this weird behaviour where it thinks there might be clipping and then lowers the volume accordingly for a second. If you set the volume to 100% on every slider, the driver's limiter is pretty much guaranteed to activate, and your sound will become wobbly and have slightly reduced punch. My previous soundcard was a Realtek onboard that I blew up, which didn't have this behaviour. I never experienced any clipping distortion either, so for now I'm going to put this on the Xonar driver being overly cautious.

The default settings, however, should be that the Left and Right slider in the mixer are at about 75%, and the main turning button on the interface at 50%. You should probably leave this as is, or experiment. Of course, if you're not hearing anything funny at all: don't worry about it! smile.gif

QUOTE
On the FlexBass tab, is there any threshold value to the LFE Crossover Frequency?


Only if you're hearing distortion from your 2 satellite speakers. The slider exists because every speaker setup is different, so you should play around. It's possible that nothing needs to be done.

This post has been edited by dhromed: Nov 10 2012, 14:59
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androdion
post Nov 10 2012, 16:03
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QUOTE (dhromed @ Nov 10 2012, 13:58) *
Yes, it will resample to the sample rate you specify. Whether this at all audible is another matter. I keep it at 44.1.

So if the source signal has an intermediate sample rate which isn't one of the predefined, say 100Khz (>96 but <192) it will have to be played at 192Khz?

QUOTE (dhromed @ Nov 10 2012, 13:58) *
The manual I've got says the exact opposite. The sliders operate on a percentage of full-scale, that is, 100 = 0dBFS.

The Xonar driver has this weird behaviour where it thinks there might be clipping and then lowers the volume accordingly for a second. If you set the volume to 100% on every slider, the driver's limiter is pretty much guaranteed to activate, and your sound will become wobbly and have slightly reduced punch. My previous soundcard was a Realtek onboard that I blew up, which didn't have this behaviour. I never experienced any clipping distortion either, so for now I'm going to put this on the Xonar driver being overly cautious.

The default settings, however, should be that the Left and Right slider in the mixer are at about 75%, and the main turning button on the interface at 50%. You should probably leave this as is, or experiment. Of course, if you're not hearing anything funny at all: don't worry about it! smile.gif

That's probably it, the driver issue you mention, because indeed the interface is at 76% on Mixer and 50% on master volume. With the system's volume cut at 50% on the Xonar and the Mixer (which is the L/R channel amplification) at those 76%, the volume of my speakers is still enough to listen to loud music at only 25-30% of their capacity. If I had the Mixer on 100% I'd barely be able to move the control volume on the speakers upwards without significantly boosting the volume level. smile.gif

QUOTE (dhromed @ Nov 10 2012, 13:58) *
Only if you're hearing distortion from your 2 satellite speakers. The slider exists because every speaker setup is different, so you should play around. It's possible that nothing needs to be done.

Yeah, I've been playing around with it for a while. Experimenting with EQ and LFE, trying to remove the excessive rumble from the midrange. I have my LFE settings at 170Hz as of now, which is the boomier region of my speakers (120-250Hz) and things are seemingly well.

Which leads me to ask, has anyone made a guide of some sorts to the Z-2300 speakers? Yes, they're old but they're pretty good for 2.1! I'm constantly trying to squeeze as much definition from them as possible without "over-eqing" (I follow the 6dB rule) but I'm always up for a bit of tweaking.

Oh, and thanks for the replies. wink.gif
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androdion
post Nov 10 2012, 17:52
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I've been reading a lot into it and ended up on this article: http://people.xiph.org/~xiphmont/demo/neil-young.html

I've tried doing the "Intermod Tests" and strangely enough three out of four of the samples gave back perceivable sounds, which according to the article it shouldn't. This happened with a flat EQ, no LFE active and no effects whatsoever, with the sampling rate put to 96Khz.

Any reason for that to happen, and most of all, what does that mean in practical terms? That I have distortion in my sound system? Meh, that's what I get from reading stuff which is a notch above my pay grade! tongue.gif
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saratoga
post Nov 11 2012, 01:20
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If you have to turn up the volume very high to hear distortion, it may be normal.

If you get it at low volume, it means you have some device that is introducing a lot of distortion (bad resampling, bad amp, speaker with high distortion, etc.)

Does it go away if you switch the sample rate to 44.1k?
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mjb2006
post Nov 11 2012, 07:00
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Where were you playing the Intermod Tests? I would expect that if you play them in your browser, they'd have issues because they're played through the MME engine, which on Windows 7 requires a patch (click) to avoid a resampling bug.

This post has been edited by mjb2006: Nov 11 2012, 07:02
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androdion
post Nov 11 2012, 15:08
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QUOTE (mjb2006 @ Nov 11 2012, 06:00) *
Where were you playing the Intermod Tests? I would expect that if you play them in your browser, they'd have issues because they're played through the MME engine, which on Windows 7 requires a patch (click) to avoid a resampling bug.

Yes, I was playing them through the browser as I had no idea about that functionality. I downloaded all four files and played them through WMP and now I can't hear any noise or distortion, apart from a small crackling at the beginning of sample one and four. However I don't think it has anything to do with the tests but more with the making of the samples, as it's that small crackling noise that you sometimes hear at the beginning of songs, which is usually caused by bad cutting on the studio. I actually have a music CD where the first song of the album has this kind of noise so I'm not worried.

Thanks for the help guys, I've learned a few more interesting things about audio. wink.gif
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