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  1. #11
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    Quote Originally Posted by Julf View Post
    No. Any volume adjustment will affect the bits (as the data has to be scaled). Using primitive, non-dithered scaling, the upper bits only stay unchanged when the attenuation is an exact power of 2.
    I see. So volume must be full to pass an unaltered signal?

    Thanks
    Jason

    Edit... Is the situation the same for a pi running max2play?

  2. #12
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    Quote Originally Posted by doctor_big View Post
    I see. So volume must be full to pass an unaltered signal?

    Edit... Is the situation the same for a pi running max2play?
    If you change the volume, the signal is altered, by definition. Doesn't matter what device or software you use.

    Only exception is when you don't actually change the volume, but only send volume change requests "down the line" (to a smart enough DAC, for example) - but at some point the actual change has to happen.

    But does it matter? Why do you need an "unaltered" signal? If you send an analog signal to an analog volume potentiometer, that signal gets altered too.
    "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

  3. #13
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    Quote Originally Posted by Julf View Post
    No. Any volume adjustment will affect the bits (as the data has to be scaled). Using primitive, non-dithered scaling, the upper bits only stay unchanged when the attenuation is an exact power of 2.
    I think what doctor_big is referring to is that the Touch's volume scaling factors for higher volume levels are arranged so that multiplying 16-bit input gives an exact 24-bit result to the DAC or digital out. It does this by making sure all bits of the scaling factor below the most-significant 8 bits are zero for all scaling factors down to a certain level of attenuation. I can't remember if that is down to -60dB - there was a fairly recent discussion on this, but I didn't find it with a quick search.

  4. #14
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    I believe it's more like down to -48db or something like that, but yes I heard this is the case.
    --
    Hardware: 3x Touch, 1x Radio, 2x Receivers, 1 HP Microserver NAS with Debian+LMS 7.9.0
    Music: ~1300 CDs, as 450 GB of 16/44k FLACs. No less than 3x 24/44k albums..

  5. #15
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    Quote Originally Posted by Julf View Post
    If you change the volume, the signal is altered, by definition. Doesn't matter what device or software you use.

    Only exception is when you don't actually change the volume, but only send volume change requests "down the line" (to a smart enough DAC, for example) - but at some point the actual change has to happen.

    But does it matter? Why do you need an "unaltered" signal? If you send an analog signal to an analog volume potentiometer, that signal gets altered too.
    Let's not go down the rabbit hole.

    My point is, can I leave the volume on my Pi or Touch at around 60%, set pre/amp gains accordingly, and then use the Touch volume control as a tune-up for minor changes? Will I still get a full 16bit signal? Or will it start truncating and dithering?

    Is there a point at where a lower volume point introduces audible issues - say, if I set the Touch volume at 10% and then jack up the volume on my preamp?

    Jason

  6. #16
    Senior Member Julf's Avatar
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    Quote Originally Posted by doctor_big View Post
    My point is, can I leave the volume on my Pi or Touch at around 60%, set pre/amp gains accordingly, and then use the Touch volume control as a tune-up for minor changes?
    Yes.

    Will I still get a full 16bit signal? Or will it start truncating and dithering?
    You will start getting truncation and/or interpolation as soon as you turn down the volume at all, but it won't affect the upper 16 bits until below -48 dB. I would have thought that is way below 60%.

    Is there a point at where a lower volume point introduces audible issues - say, if I set the Touch volume at 10% and then jack up the volume on my preamp?
    Well, theoretically at least you could turn down the volume until there is only 1 or 2 bits of resolution left, and then amplify that up to normal listening volumes... but unless your gain structure is way, way out of wack, there is no reason to worry.
    "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. #17
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    Quote Originally Posted by Julf View Post
    Yes.



    You will start getting truncation and/or interpolation as soon as you turn down the volume at all, but it won't affect the upper 16 bits until below -48 dB. I would have thought that is way below 60%.
    I'd like to know where this correlates to in regard to LMS volume setting.

    Quote Originally Posted by Julf View Post
    Well, theoretically at least you could turn down the volume until there is only 1 or 2 bits of resolution left, and then amplify that up to normal listening volumes... but unless your gain structure is way, way out of wack, there is no reason to worry.
    With only one or two bits of resolution, this would be very audible, I'd think, and not of much use given the topic and drift of this thread.

    Again, it'd be nice to know where the sweet spot is in regard to a) keeping the full 16 bits and b) having some wiggle room on either side for fine-tuning the volume via remote control.

    Thanks,
    Jason

  8. #18
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    I don't know what the actual remaining bit depth is when i do it but i use a SBT analogue out as a pre-amp connected to a small tripath style class D amp. Normal use the volume slider sits around 30-35, and for fun it's more like 60%. Sounds fine in a non critical listening environment in both cases but I'll grant you that's not necessarily conclusive.

    (Should add, the digital volume control on the SBT is noticeably superior to the analogue potentiometer on the class D amp..)
    Last edited by drmatt; 2017-03-31 at 08:17.
    --
    Hardware: 3x Touch, 1x Radio, 2x Receivers, 1 HP Microserver NAS with Debian+LMS 7.9.0
    Music: ~1300 CDs, as 450 GB of 16/44k FLACs. No less than 3x 24/44k albums..

  9. #19
    Senior Member Julf's Avatar
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    Quote Originally Posted by doctor_big View Post
    I'd like to know where this correlates to in regard to LMS volume setting.
    Maybe load a sound level meter onto your phone?

    -48 dB is quite a lot - it's the difference between normal listening level and the sound of a whisper.

    Again, it'd be nice to know where the sweet spot is in regard to a) keeping the full 16 bits and b) having some wiggle room on either side for fine-tuning the volume via remote control.
    As anywhere above the -48 dB point is OK, I suggest turning the LMS volume up to 100%, adjusting the analog amp volume to the loudest you would ever want, and turning down LMS from there.
    "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. #20
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    Quote Originally Posted by Julf View Post
    Maybe load a sound level meter onto your phone?

    -48 dB is quite a lot - it's the difference between normal listening level and the sound of a whisper.



    As anywhere above the -48 dB point is OK, I suggest turning the LMS volume up to 100%, adjusting the analog amp volume to the loudest you would ever want, and turning down LMS from there.
    Good idea - Thanks!

    Jason

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