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  1. #1
    Senior Member Archimago's Avatar
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    Internet Blind Test: Linear vs. Minimum Digital Filters...

    Hello everyone, it's up!

    I know some people have strong feelings about digital upsampling filters and there's especially the notion of minimum phase filters being superior or more natural sounding than the typical linear filters used in most DACs.

    Here's an opportunity to try it out for yourself and let me know if you hear a difference!

    Note that the files are high-resolution 24/176 so please make sure your DAC is capable of this bit- and sample-rate.

    Test will conclude on June 25th so please submit your results by that time.

    Instructions and test download:
    http://archimago.blogspot.com/2015/0...s-minimum.html

    Thanks,
    Archimago
    Archimago's Musings: (archimago.blogspot.com) A 'more objective' audiophile blog.

  2. #2
    Senior Member Wombat's Avatar
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    If you really used SoX with the steep filter of 99% it isn't exactly real-world. The high amount of ringing introduced with 99% is completely maintained in the 176kHz upsampled signal.
    A DAC playing back the 44.1kHz signal never has such a steep filter imho.
    Transporter (modded) -> RG142 -> Avantgarde Acoustic based 500VA monoblocks -> Sommer SPK240 -> self-made speakers

  3. #3
    Senior Member Archimago's Avatar
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    Hopefully...

    In doing this we can see if there is any significant preference among respondents!

    I want to know, EVEN with this amount of (pre-)ringing, whether suppression with the minimum phase setting actually results in a significant difference detected.

    1. Is there significant *preference* in a naturalistic sample for one setting vs. another?

    2. Are listeners able to consistently "prefer" one variety over another among the 3 samples? Ie. They keep preferring the same type of filter? How many of these potential "golden ears" are there? Of course it's also possible that the folks with these *systems* are particularly susceptible to high frequency nonlinearities.

    3. Can we detect cohort effect among musicians, production folks, and even audio reviewers? I have been told for example that musicians and those who record and produce music may be able to detect the differences better...

    In any event, the filter effect is clear. Trading strong pre-ringing at 22kHz for high frequency phase shift. Is there an audible difference and can some people consistently tell?

    We can deal with the idea of suppressing ringing and such in a future test. One variable at a time :-).

    BTW: I resample with these steep filters all the time. So I have vested interest in changing how I do things based on the results!
    Archimago's Musings: (archimago.blogspot.com) A 'more objective' audiophile blog.

  4. #4
    Senior Member Wombat's Avatar
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    My little critic shouldn't invalidate anything of your well done test. It is only that many use filters with a transition band of 1-2 kHz to avoid any problems steep filters may have.
    On the other hand there are no real convincing arguments there is really a problem, only some marketing papers, anectodes or faulty experiments
    Transporter (modded) -> RG142 -> Avantgarde Acoustic based 500VA monoblocks -> Sommer SPK240 -> self-made speakers

  5. #5
    I can tell the difference with nearfield monitors .In a hifi environment ,I doubt it.

  6. #6
    Senior Member Archimago's Avatar
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    Quote Originally Posted by Wombat View Post
    My little critic shouldn't invalidate anything of your well done test. It is only that many use filters with a transition band of 1-2 kHz to avoid any problems steep filters may have.
    On the other hand there are no real convincing arguments there is really a problem, only some marketing papers, anectodes or faulty experiments
    No worries Wombat! I totally accept the critique and welcome it since it's good to know and realistically present the findings (if any!).

    Like you said, there are marketing papers out there and certain research presented (often by parties with vested interests). I'd love to see we, the consumers weigh in!
    Archimago's Musings: (archimago.blogspot.com) A 'more objective' audiophile blog.

  7. #7
    Senior Member Archimago's Avatar
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    Quote Originally Posted by jimmypowder View Post
    I can tell the difference with nearfield monitors .In a hifi environment ,I doubt it.
    JIMMY:

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    Please, have a listen on the nearfield monitors! Let me know what you hear!
    Archimago's Musings: (archimago.blogspot.com) A 'more objective' audiophile blog.

  8. #8
    Senior Member Mnyb's Avatar
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    Good luck with this ! I can't be a test subject this time due to the 24/96 "limit" of my system .

    However is any comparison done to the original ? I say if what if any of the converted files sounds different ? They're really should not then we might have got in the territory of pleasantly colouring artefacts . The ones sounding different from the original is broken ?

    Does any of the filters have a frequency drop inside of 20kHz ? There have been many SoX filters suggested by some users over the years , some quite unorthodox often made on the fly by for example convert.conf settings in lms or by other means with other systems . Some of these give a slight attenuation of the treble ? I always wondered if we just have a fancy tone control here .
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  9. #9
    Senior Member Wombat's Avatar
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    Quote Originally Posted by Archimago View Post
    No worries Wombat! I totally accept the critique and welcome it since it's good to know and realistically present the findings (if any!).

    Like you said, there are marketing papers out there and certain research presented (often by parties with vested interests). I'd love to see we, the consumers weigh in!
    Absolutely! If people don't hear day and night differences with this strong ringing i doubt it ever can become a problem. Just read at CA about every digit from 0-2000 changes sound "obviously" in the thread about recommended iZotope settings
    Unfortunately here is also no 176.4 native support.
    Just for illustration a simple pic showing the ringing distribution for sox 99% 44.1 -> 176.4, L and M
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    Transporter (modded) -> RG142 -> Avantgarde Acoustic based 500VA monoblocks -> Sommer SPK240 -> self-made speakers

  10. #10
    Senior Member Archimago's Avatar
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    Quote Originally Posted by Wombat View Post
    Absolutely! If people don't hear day and night differences with this strong ringing i doubt it ever can become a problem. Just read at CA about every digit from 0-2000 changes sound "obviously" in the thread about recommended iZotope settings
    Unfortunately here is also no 176.4 native support.
    Just for illustration a simple pic showing the ringing distribution for sox 99% 44.1 -> 176.4, L and M
    Exactly!
    Archimago's Musings: (archimago.blogspot.com) A 'more objective' audiophile blog.

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