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  1. #511
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    Quote Originally Posted by darrenyeats View Post
    Can you remember where you read that?
    Sorry, this goes back to 2005 or 2006. I have tried searching the forums to find the threads that discussed the firmware updates in detail, but without success. But I do distinctly remember seeing discussions about how the volume adjustment had been modified to avoid the need to use the 25th bit for all but extreme attenuation settings.

    The one place where this is mentioned in passing is in an exchange between myself and Patrick Dixon (posts #11 to #16) in this thread:
    http://forums.slimdevices.com/showth...-control/page2

    Quote Originally Posted by darrenyeats View Post
    According to my tests on the TOUCH, vol approx 30-100 seems to obey approx 0.5dB per step (which would make vol 40 approx -30db) but below 30 the drop off in dB is more rapid.
    I can't say anything about the Touch. The firmware change I remember was for the old players (SB2/3, TP), from way before the Duet or Touch were introduced.
    Transporter -> ATC SCM100A

  2. #512
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    Thanks Clive.

    To summarise what members utgg has clarified for us, a Touch volume setting of 40 (~-30db) or higher will be bit perfect with 16 bit source. So in this respect at least, similar to earlier Squeezeboxes according to your link.

    That just leaves us (well, me anyway) the worry of volume 39 or lower with 16 bit source or volume below 100 with 24 bit source.
    Last edited by darrenyeats; 2015-10-27 at 16:23.
    Check it, add to it! http://www.dr.loudness-war.info/

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  3. #513
    Senior Member Mnyb's Avatar
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    Quote Originally Posted by darrenyeats View Post
    Thanks Clive.

    To summarise what members utgg has clarified for us, a Touch volume setting of 40 (~-30db) or higher will be bit perfect with 16 bit source. So in this respect at least, similar to earlier Squeezeboxes according to your link.

    That just leaves us (well, me anyway) the worry of volume 39 or lower with 16 bit source or volume below 100 with 24 bit source.
    Good morning .. ( of to work in a minute )

    With 24 bit sources you have a kind of wiggle room anyway so not quite 100 ( I'm again not going to figure the exact math, cue utgg ... )
    We have discussed that no practical DAC's are really 24 bit ( more like 19-21 bit on a good day ).
    That also goes for ADC and other recording equipment assume that the best modern recordings ever made can reach the same level say 19-20 bits ,and that's a wide margin they are probably not that good .

    Typical recordings don't even challenge the cd system ( most of the recorded history including audiophile favourites like dstm ) , but this is the audiophile forum so assume your best records on your best system

    A guess 80-90 volume is ok for the best recordings ever made ?

    I have casually assumed that I have a practical 20 bit system at home ( best case quiet day ) and the recordings are at best 16 bit even if branded as 24 bit ( 8 bit of random noise is not going to make it better, even if you bougth them from HD tracks ) .

    So what gives ? I think I can use some of the Touch volume 70-90 and all of my meridian volume ( properly dithered ) without even theoretically limit my sq .

    I again I think the gain of the system is of more importance sending a quit signal to the DAC means it closer to its noise floor but preamp or power amp gain if of concern .

    And I use bits and dB as the same thing ? You can assume that with properly dithered modern equipment .
    --------------------------------------------------------------------
    Main hifi: Rasbery PI digi+ MeridianG68J MeridianHD621 MeridianG98DH 2 x MeridianDSP5200 MeridianDSP5200HC 2 xMeridianDSP3100 +Rel Stadium 3 sub.
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  4. #514
    Senior Member Julf's Avatar
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    Quote Originally Posted by Mnyb View Post
    A guess 80-90 volume is ok for the best recordings ever made?
    Pretty much, yes. So far I haven't come across a single recording going beyond 90 dB or so.
    "To try to judge the real from the false will always be hard. In this fast-growing art of 'high fidelity' the quackery will bear a solid gilt edge that will fool many people" - Paul W Klipsch, 1953

  5. #515
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    Some recordings are very quiet others very loud. Sometimes I don't want to listen at a loud volume. I tend to use 30-65 most of the time but I occasionally need say 20-80. I don't want a physical preamp. Therefore I expect my digital volume to be blameless. 80-90 is not a realistic use case, far too narrow. (BTW I'd avoid above 90 in any event to give my DAC DSP headroom for upsampling/ASRC.)

    Obviously better than any attenuation is getting the gain structure right. I've done all I can on that front, that was step one.

    As we know, noise is far far more benign than distortion. I'd rather dither everything than have bit perfection but only for 16 bit and only certain volume levels.
    Last edited by darrenyeats; 2015-10-28 at 01:57.
    Check it, add to it! http://www.dr.loudness-war.info/

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  6. #516
    Senior Member Julf's Avatar
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    Quote Originally Posted by darrenyeats View Post
    BTW I'd avoid above 90 in any event to give my DAC DSP headroom for upsampling/ASRC.
    So you suspect your DAC hasn't been designed with enough headroom?
    "To try to judge the real from the false will always be hard. In this fast-growing art of 'high fidelity' the quackery will bear a solid gilt edge that will fool many people" - Paul W Klipsch, 1953

  7. #517
    Senior Member Mnyb's Avatar
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    Quote Originally Posted by Julf View Post
    So you suspect your DAC hasn't been designed with enough headroom?
    Do you remeber our tread about "intersample overs" not many DAC especially older ones shave not acounted for this effect , which in turn is an artefact of modern record producing .
    DAC mfg is often hunting specs so even if some filters alows for gain adjustments in theri parameters you get better snr if you don't so they just assume perfect recordings
    --------------------------------------------------------------------
    Main hifi: Rasbery PI digi+ MeridianG68J MeridianHD621 MeridianG98DH 2 x MeridianDSP5200 MeridianDSP5200HC 2 xMeridianDSP3100 +Rel Stadium 3 sub.
    Bedroom/Office: Boom
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    (spares Touch, SB3, reciever ,controller )
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  8. #518
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    Quote Originally Posted by Mnyb View Post
    Do you remeber our tread about "intersample overs" not many DAC especially older ones shave not acounted for this effect , which in turn is an artefact of modern record producing .
    DAC mfg is often hunting specs so even if some filters alows for gain adjustments in theri parameters you get better snr if you don't so they just assume perfect recordings
    This relates to the function of the newest Benchmark DAC, the DAC2. Pasted below is their brief discussion in their advertising. I think there is a longer discussion somewhere on their website. (I'm not claiming any of this is correct, as I don't know....just pointing out this example).

    High Headroom DSP - with 3.5 dB "Excess" Digital Headroom

    All of the digital processing in the DAC2 HGC is designed to handle signals as high as +3.5 dBFS. Most digital systems clip signals that exceed 0 dBFS. The 0 dBFS limitation seems reasonable, as 0 dBFS is the highest sinusoidal signal level that can be represented in a digital system. However, a detailed investigation of the mathematics of PCM digital systems will reveal that inter-sample peaks may reach levels slightly higher than +3 dBFS while individual samples never exceed 0 dBFS. These inter-sample overs are common in commercial releases, and are of no consequence in a PCM system until they reach an interpolation process. But, for a variety of reasons, virtually all audio D/A converters use an interpolation process. The interpolation process is absolutely necessary to achieve 24-bit state-of-the art conversion performance. Unfortunately, inter-sample overs cause clipping in most interpolators. This clipping produces distortion products that are non-harmonic and non-musical . We believe these broadband distortion products often add a harshness or false high-frequency sparkle to digital reproduction. The DAC2 HGC avoids these problems by maintaining at least 3.5 dB of headroom in the entire conversion system. We believe this added headroom is a groundbreaking improvement.
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  9. #519
    Senior Member Julf's Avatar
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    Quote Originally Posted by Mnyb View Post
    Do you remeber our tread about "intersample overs" not many DAC especially older ones shave not acounted for this effect
    Indeed, and yes, intersample peaks are an issue with older DACs, but I would expect modern designs to deal with it - it is pretty easy to do, after all.
    "To try to judge the real from the false will always be hard. In this fast-growing art of 'high fidelity' the quackery will bear a solid gilt edge that will fool many people" - Paul W Klipsch, 1953

  10. #520
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    Julf, I have a DAC1. Set up the right way anyway, it's still a good DAC.
    http://www.pinkfishmedia.net/forum/s...d.php?t=137152
    Check it, add to it! http://www.dr.loudness-war.info/

    SB Touch

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