kX vs Creative audio quality: 1 - 0 - why?

Discussion in 'General Discussion' started by M4rtijn, Jul 30, 2006.

  1. M4rtijn

    M4rtijn New Member

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    In short:

    It seems to me my Audigy-2 produces (high-frequency?) noise when using the kX drivers, whereas the sound from the Creative drivers is clean.

    Explanation:

    I connected the Audigy-2 to my new mixer, a Pioneer DJM-400. This mixer has a built-in 24 bit / 96 kHz sampler. It struck me that any sound I recorded from the Audigy was layered in a bed of white noise. Even when I played no sound at all, the mixer's sampler would trigger to the noise and record 4 bars of noise. Both the front and the rear channels had this problem.

    For comparison: my turntable, connected to that mixer, did not nearly produce such a level of noise, and also my computer's on-board SoundMax device yielded a clean recorded sample. Strange is this: you don't really hear the noise when you just play the Audigy-2 through the mixer, it only appears after having been sampled... Like there is some (high?) frequency content in the audio that the (high quality!) sampler reads as noise.

    This I could not believe: my supposedly top-notch soundcard appeared to be crippled compared to my other audio sources. The noise was really so loud, that I could not believe (even) Creative selling a soundcard with such poor quality.

    That's when I decided to uninstall the kX drivers and install (for the first time ever!) the Creative drivers - quite against my wishes, as I love the kX drivers for all its functionality.

    To my surprise: the noise was gone!

    One question remains: why? Does creative activate a low-pass filter that kX does not use? That would explain why some people describe the sound of kX as "crisper"... Or is there a output setting in kX that I missed?
     
  2. Doug W

    Doug W Active Member

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    One advantage of being a middle aged musician is that I am no longer bothered by these annoying high frequency noises so I don't have to deal with them. I don't know if the Creative drivers have a default low pass filter but with kX you can add any filters you want and make custom DSPs.

    If you are happy with the Creative drivers, you should stay with them but once you get the hang of the kX DSP however, it becomes a simple deal to make a basic DSP and then add EQ, filters, reverb as needed.

    In my opinion you need:

    Lex's ProFX
    Max's UFX
    and also Read Lex's "How to setup your own DSP"

    all located here:
    http://www.driverheaven.net/announcement.php?f=67&announcementid=18

    Or just wait a few years and those pesky high frequencies will be gone anyway.
     
    Last edited: Jul 30, 2006
  3. Nando Dominguez

    Nando Dominguez New Member

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    :rofl: :rofl: :rofl: :rofl:

    Regards Doug
     
  4. Maddogg6

    Maddogg6 Tail Razer

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    I hear this too when UNUSED inputs are enabled and volume is turned up (mostly AC97 sources - but a little with other inputs as well - especially if using something like AGC or a compressor - in line with an unused/un-connected input.

    So - turn down ALL other inputs except used ones.
     
    Last edited: Jul 30, 2006
  5. M4rtijn

    M4rtijn New Member

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    Thank you all for taking part in this discussion. However, I regret to have a feeling that your suggestions do not provide the solution... To Maddogg6: I have muted _all_ inputs, even tried to solve it by completely clearing the DSP: it changes nothing. To Doug W: I suspect it is not a DSP filter that is causing the difference, as that would only have an effect when there's actually sound playing, right?. The difference is already noticable as soon as Windows has boot up - as soon as the driver has initialized. I have a feeling that the creative drivers initialize the analog part of the soundcard differently - could there be an analog low-pass filter on the Audigy 2 (thus outside the 10k2) that can be switched on and off?

    I also wish to emphasize that I have already used the kX drivers for years now, and have never heard this noise. When I am just playing audio, I don't hear the noise either - at least, it is not noticable at normal playback levels. Yet after having been sampled (96 kHz, 24 bit) by my mixer, the recorded sample is layered in noise when I use the kX drivers. At first, I thought it was my mixer's fault, but then I discovered that this noise is absent when I use any other source, and also when I use the Creative drivers - which I'd rather not use, because I am already missing kX's seperate directsound devices!
     
  6. Lex Nahumury

    Lex Nahumury DH Senior Member

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    @mr4tijn;


    There are too many other factors to consider but,
    do you perhaps use default DSP with the Reverb plugin?

    By design, reverb and a few other DSP plugins can
    produce digital artifacts percieved as 'noise'
    even if no signal is applied to them.

    If you realy want to examine the analog =output= noise floor
    of your soundcard, you best start with a 'clean' (not empty) DSP setup.
    (if you know what I mean)

    HTH,

    /Lex.

    PS:
    BTW; What really is of interest is the actual SNR.
    PPS:
    What audigy card type number?
    IIRC, users have reported 'hiss' on certain audigy cards.
     
    Last edited: Jul 31, 2006
  7. M4rtijn

    M4rtijn New Member

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    @Lex:
    I did try removing the reverb & chorus plugins, to no avail. The soundcard type is SB0244 (iirc). Again, I wish to empasize that the noise I mention is normally not(!) audible, only after sampling. This make me believe that this noise is present beyond the audible range (> 20 kHz) and wrapped into the audible range by the mixer's sampler. While googling on the net for answers, I found a discussion (http://www.bebits.com/talkback/3209) mentioning the activation of an "interpolation ROM (lowpass anti-aliasing filter)". At (http://mira.aavso.org/pipermail/aavso-sid-list/2005-March/000900.html) a 24 kHz low pass filter is mentioned too. According to (http://www.n9vv.com/K2WS.html) an Audigy 2 ZS produces a lot of broadband noise - I suspect this has been measured with the Creative drivers - makes me wonder what this picture would look like with the kX drivers.
    Could it be that this (analog?) anti-aliasing filter is always on in the Creative drivers, and always off using kX drivers? Or that the kX drivers only activate it "when deemed necessary"? Or is my reasoning just nonsense?
     
  8. bennetng

    bennetng New Member

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    What you said is possible. DAC can use noise shaping (adding high frequency noise) to enhance sound quality in low frequency. If you sample the output of your soundcard then pitch-shift the sound (using a sampler) then the high-frequency noise will become audible. To learn more about noise shaping, you can visit this page
    http://audio.rightmark.org/lukin/dither/dither.htm

    Noise shaping is usually good for normal listening but bad for special application such as sampling.
     
    Last edited: Jul 31, 2006
  9. M4rtijn

    M4rtijn New Member

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    Hmm... sounds like there is a good deal of truth in this: the DAC is the CS4382, which is a 1-bit delta-sigma DAC. Indeed, such a DAC uses noise-shaping to push the noise from the audible range to frequencies beyond 20 kHZ. According to the spec sheet (http://www.streammachine.com/en/pubs/proDatasheet/CS4382_F1.pdf) the DAC contains a selectable interpolation filter before the delta-sigma conversion and an analog filter right after the conversion. I suspect this interpolation filter might be set to a different setting in the Creative drivers, but unfortunately I have no means to verify any of this...

    You say noise shaping is bad for sampling - is that known for a fact or do you have more experience with that? Because this is something I hadn't heard of before...

    PS: there is no pitch-shifting involved in this problem.
     
  10. jiiteepee

    jiiteepee Active Member

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  11. bennetng

    bennetng New Member

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    The frequency response of the shaped noise is only good for the ears when it is not altered. A sampler always has functions such as pitch-shifting, modulation, pitch-bend, tuning and LFOs to alter a sound's pitch. Musicians make use of these functions to create many different sounds from a single sample, therefore samples should not be noise-shaped. Also, even if a user does not intentionally use the functions mentioned above, a sampler may not be able to bypass the processing at all.

    I still cannot make sure that the noise you heard is caused by noise shaping and a (later than Creative) low pass filter because you didn't provide any audio samples or spectrum graph. A Audigy2 ZS review shows that (some?) Creative drivers are also heavily noise shaped:

    Creative Audigy2 ZS Sound Card Review
     
    Last edited: Aug 9, 2008
  12. scalt505

    scalt505 New Member

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    I am not sure if this is due to the same problem, but it might.

    My setup consists of having the outputs of my Audigy 2 (SB0350) plugged into a multizone amplifier. On this amplifier, there is a auto shut-off when there is no input for the fifferent channels (no sound comming in). While using other drivers then the kx drivers, this works fine, however, when using the kx drivers, the auto shut-off never goes into effect. It would seem as though there is something comming out of the soundcard, although I can hear no noise and the "peak" module from the DSP doesn't show anything either.

    I hope someone finds a solution to this, because it would be very usefull for me too.

    Thanks
     
  13. jiiteepee

    jiiteepee Active Member

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    Could this be just low hissing sound from Mic/Line/etc. sources in soundcard, when left open in mixer app?

    jiitee
     
  14. chris.miller

    chris.miller New Member

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    So, let me get it straight: the only sound source that produces that kind of noise is you Audigy card with kx drivers plugged into your Pioneer mixer with 24/96 sampling? What I would like to know is: are you outputting analog from Audigy? (it sounds like it, but just checking.) Do you have another Creative card that you can use to check wether it behaves the same way with kx? It could be an isolated case of a rather peculiar kind of error on your card...one that I have not heard of.

    Make sure you are not playing back 44.1kHz from Creative...only 48, because trying to resample a 44.1k to 96 would really mess up the sound. It is still preferable to avoid recording sound from the soundcard to another mixer... Could you tell me what is it that you want to transfer this way?

    I also use a Creative card (Live 5.1 Digital) which I plug into a digital mixer (Tascam SX1) at 24/48, not 24/96 like you. But there is no such noise coming from my Creative card. I use digital out from Creative and still the sound is perfect. And I am only using it for monitoring, not recording!

    Chris
     
  15. M4rtijn

    M4rtijn New Member

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    I think scalt505's amplifier not shutting off is caused by the same: audio that is there but that you don't hear.

    I don't think that I could provide a "sample" of this issue like bennetng sugggests: you don't hear it and besides, it would only work if the sampler would correctly record the entire spectrum the Audigy outputs... Maybe I could provide a sample of the noise-drowned sound of the sampler, but I think you can all remember the noise of analog tape: multiply that by 10 and you've got it :) The article on digit-life.com that bennetng mentions is certainly interesting. The diagrams show that the Audigy produces a lot of noise between 30 an 100 kHz. On the other hand, it also states that the Audigy 2 (ZS) does not have a 20kHz low-pass filter like the AES17 used by Creative for measurements.

    It's definitely not any open source, like suggested by Jiiteepee: that would produce _audible_ noise, I know... I have just connected both the front and the rear analog outputs to the mixer's line-in. Connecting only the front or only the rear doesn't matter. I discovered the issue just playing mp3's using WinAmp (DirectShow). Then I found out the (inaudible!) noise is still there if I am not playing anything at all! Just not with the Creative drivers, which rules out a hardware defect.

    I don't have an other Creative card, but older cards have an entirely different signal path anyway. To make sure it is not something else inside my pc (like the cpu or videocard) that's causing this, I tried the SoundMax onboard audio: it does not have this noise problem.
     
  16. M4rtijn

    M4rtijn New Member

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    Because I got curious how Linux's ALSA drivers would perform, I booted the latest version of Knoppix (5.0.1). Using these drivers, I have no problem: no noise after sampling...
     

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