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  1. #1
    Hibster_2000 Guest

    Default What sample rate?

    My DAC is capable of 24 bit 192KHz.
    I believe that my ears are capable of a lot less, so is there any benefit from running more than 44.1kHz sample rate?
    If so, why?

  2. #2
    montesquieu Guest

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    In my view sample rate is (for the most part) irrelevant unless we are talking lower sample rates than redbook eg MP3 with shedloads of compression. The most important feature in any digital replay is the recording and mastering - a good quality redbook 44.1k file will sound better than a poorly recorded and mastered hi-res file regardless of the kit that it's on.

    The next most important factor in digital replay is the output stage. The vast majority of CDPs and DACs use op amps of variable quality, that can make or break a component. Some of course are very good and with the right attention paid to power supplies, screening, connectors etc can sound fantastic. Others have valve output - I like to think about DACs as a preamp without a volume control - so the questions to ask are what's the quality of what's receiving the raw signal from the DAC chip at the end of the digital to analogue conversion process, adding gain, and outputting it to the connectors on the back?; what's the output impedance? essentially, is there anything constraining its performance as a preamp amplifying and outputting the converted signal to the next component in the chain?

    I happen to prefer non-oversampling redbook-focused R2R chips such as the AD1865 in my own Audio Note based DAC (another example would be the TDA1541), but other than 'features' (such as the ability to play lots of different resolution files, or to manipulate the chip output in some form using digital signal processing) I think the chip is actually the least important part of the thing, certainly less important than the receiver chip/master clock/USB conversion interface and other related circuitry in bringing in the digital signal ready for analogue conversion with minimal error.

    Others I'm sure will disagree but I would say focus on getting redbook right, high-res I'm sure is fun to play with but the vast majority of music out there is 41.1k and it's surely that that requires focus.

  3. #3
    Join Date: Aug 2009

    Location: Staffordshire, England

    Posts: 37,779
    I'm Martin.

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    There's no benefit from running more than 44.1kHz sample rate.
    Current Lash Up:

    TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.

  4. #4
    Join Date: Feb 2010

    Location: Moved to frozen north, beyond Inverness

    Posts: 2,602
    I'm Dave.

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    Quote Originally Posted by Macca View Post
    There's no benefit from running more than 44.1kHz sample rate.
    That's a bit definite.

    Theoretically there's not a lot of point, but theory doesn't always work. Some - such as Grant - claim a slight improvement with more quantisation levels and a higher sampling rate. This is perhaps not because the theory (based on the sampling theorem) is incorrect, but because design factors in the recording chain and in the replay equipment do lead to an audible improvement.

    A few people do genuinely seem to have hearing which can hear up to and above 20 kHz, so for them there might be a benefit in a higher sampling rate. Such people are fairly rare though, particularly among older people. I gave up worrying about TV whistle, and noise from fluorescent lights some years ago - though when I was youger these were a real pain.
    Dave

  5. #5
    Hibster_2000 Guest

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    Thanks for the replies.
    I still have relatively good hearing, as small high pitch whines from led or fluorescent bulbs etc. annoy me.
    I have been trying to get noise free 24 bit 192KHz output from my music PC to my SEG, but it just seems troublesome.
    I have dropped the sample rate to 24/96 and this seems pretty good, and does not annoy all of the dogs in the neighbourhood so much.

  6. #6
    Join Date: Aug 2009

    Location: Staffordshire, England

    Posts: 37,779
    I'm Martin.

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    Quote Originally Posted by dave2010 View Post
    This is perhaps not because the theory (based on the sampling theorem) is incorrect, but because design factors in the recording chain and in the replay equipment do lead to an audible improvement.

    .
    I'd be interested in what design factors you are taking about?

    Suspect if Grant tried to distinguish his hi rez copies from his red book standard ones without knowing which is which he would...struggle. No-one in he world has ever managed to do that. And that's leaving aside the fact that vinyl does not come close to the FR or DR of red book let alone anything higher.

    Always worth bearing in mind that if the recording equipment could not capture frequencies above 22Khz then there will be nothing there to reproduce even if it could be heard. And also that the loudspeakers used for playback would need to be capable of reproducing frequencies above 22Khz, and at sufficient levels to be audible.

    Lots of cons in audio but 'hi res' replay has to be the biggest and most successful of them by a margin.
    Current Lash Up:

    TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.

  7. #7
    Join Date: Mar 2009

    Location: South West-ish, UK

    Posts: 457
    I'm Patrick.

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    Quote Originally Posted by Macca View Post
    I'd be interested in what design factors you are taking about?
    I imagine that he's talking about the effects of anti-alias filtering before sampling, and of reconstruction filtering after conversion back to analogue.

    Deficiencies in either have the potential to alias (unwanted) high frequencies onto low frequencies so they can produce in-audio-band frequencies from out-of-audio-band frequencies.

    If you sample at 44.1KHz any energy above 22.05KHz is reflected back about 44.1KHz, so (eg) a 30KHz signal would appear at 14.10KHz (with opposite phase). You can see this effect in old western films (shot at 25fps) where a wagon wheel can start off rotating in the right direction, and then appear to rotate backwards when the wagon reaches a certain speed.

    Good design should avoid this, but the higher the sampling rate the more room the designer has to remove the unwanted signal without harming the ones you do want to retain.

  8. #8
    montesquieu Guest

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    Quote Originally Posted by Patrick Dixon View Post
    I imagine that he's talking about the effects of anti-alias filtering before sampling, and of reconstruction filtering after conversion back to analogue.

    Deficiencies in either have the potential to alias (unwanted) high frequencies onto low frequencies so they can produce in-audio-band frequencies from out-of-audio-band frequencies.

    If you sample at 44.1KHz any energy above 22.05KHz is reflected back about 44.1KHz, so (eg) a 30KHz signal would appear at 14.10KHz (with opposite phase). You can see this effect in old western films (shot at 25fps) where a wagon wheel can start off rotating in the right direction, and then appear to rotate backwards when the wagon reaches a certain speed.

    Good design should avoid this, but the higher the sampling rate the more room the designer has to remove the unwanted signal without harming the ones you do want to retain.
    Debates have long raged about upsampling and filtering - one of those ideological battles in my opinion - but the question was about playback of redbook vs higher resolution files, ie files recorded and mastered at higher bit rates. This has nothing do with upsampling which is after all just a method of manipulating data that's fed in to the system from a disk, file or stream, whatever resolution it starts at.

  9. #9
    Join Date: May 2016

    Location: Notts

    Posts: 2,741
    I'm Geoff.

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    Quote Originally Posted by Patrick Dixon View Post
    I imagine that he's talking about the effects of anti-alias filtering before sampling, and of reconstruction filtering after conversion back to analogue.

    Deficiencies in either have the potential to alias (unwanted) high frequencies onto low frequencies so they can produce in-audio-band frequencies from out-of-audio-band frequencies.

    If you sample at 44.1KHz any energy above 22.05KHz is reflected back about 44.1KHz, so (eg) a 30KHz signal would appear at 14.10KHz (with opposite phase). You can see this effect in old western films (shot at 25fps) where a wagon wheel can start off rotating in the right direction, and then appear to rotate backwards when the wagon reaches a certain speed.

    Good design should avoid this, but the higher the sampling rate the more room the designer has to remove the unwanted signal without harming the ones you do want to retain.
    Exactly, though I'm not sure about the wagon wheel analogy. I am not interested in ideological debates only sq. I have only recently become a convert to digital and I am sure that my distaste had a lot to do with poor digital processing. Using Audivarna on a reasonably powerful pc allows me to upsample redbook and even high res files. The improvement in sq is not small.

  10. #10
    Join Date: Feb 2010

    Location: Moved to frozen north, beyond Inverness

    Posts: 2,602
    I'm Dave.

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    Quote Originally Posted by Macca View Post
    Always worth bearing in mind that if the recording equipment could not capture frequencies above 22Khz then there will be nothing there to reproduce even if it could be heard. And also that the loudspeakers used for playback would need to be capable of reproducing frequencies above 22Khz, and at sufficient levels to be audible.

    Lots of cons in audio but 'hi res' replay has to be the biggest and most successful of them by a margin.
    Yet another problem would be if the recording equipment could capture frequencies above 22 kHz, then depending on how the data was processed those sounds could be mapped down into the audible range and would appear as noise - which may, or may not, be annoying. If that is going to be a problem (bats flying round the recording studio - though to my slight surprise I actually heard a bat a year or so back - I didn't think my hearing went that high ..) then the high frequencies should be filtered off either with an analogue filter, or a digital one before the signal is converted to the digital form for distribution.
    Dave

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