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  1. #1
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    volume control, bits, objective / measured results

    Hi,

    switching from remote controlled amp to non remote amp I intend to use the volume control of the SB Touch.

    Setting on the amp the volume control for the loudest I think will need (while the volume setting on the SB Touch is at 100) and afterwards during listening using the SB Touch volume control to reduce if needed. Never going below ca. 80 on the Touch.
    with my ears and system I do not hear sound quality degradation...but I am curious. :-))

    Are there any objective, measured curves of sound quality (resolution, noise, ...) for different volume settings on a Touch ?
    are there clear, measured values: what the number of the volume value on the Touch does it mean ? 100=0dB, 99= ... dB ? 98=..dB, ...90=..dB, 85=...dB, 80=..dB

    ..also: I tried 3 DAC's in the past (e.g. Denon DA-300, Musical Fidelity M1) and although heard especially with the Denon DA-300 some changes I would not say for sure that through the DAC's the sound was with higher fidelity to the original.
    At what price level would be DAC's with which for sure the sound is better ?
    ..I tend to objectivism.

    thanks for any contentfull and facts based reaction.

  2. #2
    Senior Member pippin's Avatar
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    tl;dr; is: forget about it, it's not a problem (unless you do crazy stuff), people are making this up.
    tl;dr; #2: theoretically you'll see a loss below 18% of the maximum volume in a Squeezebox system when listening to CD quality music but again you'd have to turn down the volume on the Squeezebox a lot and turn up the volume on your amp to notice it. Stay at volume levels above 25% or so and you'll be fine.

    The procedure you use to calibrate your listening volume is exactly right.

    (And none of this applies to iPeng Playback using headphones on an iPhone , there it's all completely different )
    (It also doesn't always apply to software players because SqueezeLite, for example, can use 32 bit volume resolution, too)

    What's behind it:
    1. It depends on your source material. If you have high dynamic range recordings (using 24 bit audio sample size), then you will indeed have a (theoretical) loss of signal quality. But with these ranges the digital resolution is waaaay higher than your signal-to-noise-ratio so even if you have a loss of resolution, unless you go to really low volumes it will just be within what's noise anyway. Your typical recording will hardly go beyond -100dB SNR and the resolution loss will typically be below that.

    2. If you use "normal" CD quality music (so music coming from a CD or most online streams), then the resolution of your music data is 16 bit. The resolution used by all Squeezebox models (there is no difference between Touch and Receiver here) is 24 bits. This means, only if you effective volume is below 1/128th of the maximum volume the loss will be below the resolution of your original material, so effectively will be inaudible (in reality it's even much more because your original recording will always include some noise, too).

    3. The 1/128 is the output power, not the "volume %" level you see. The output volume is logarithmic which means at high volume levels changes are bigger than with low volume changes. 1/2 of the output is is far from being the same thing as "50%" volume, it's more like of the 97% volume.

    4. This, too, is no strictly arithmetic but the devices have an individual curve that defines how the "x% volume" you see in the user interface translate to the output power. This curve is getting steeper at low volumes to allow for some resolution at low volumes. Without this, getting from 1% volume to 2% volume would be huge step and if you want to do really silent listening (e.g. with headphones) you would have huge relative volume changes.

    5. In reality, for a Squeezebox this means if you go below "18%" volume, you will see a loss in signal quality. If you go REALLY low (like at 1% or 5%) it will become audible. So what you should not do, is turning down the volume on the Squeezebox really low and then turning up the volume on your amp really high. This would amplify the noise created.

    6. Instead, you should do exactly as you did: turn the volume on your Squeezebox to 100% and set your amp to the highest volume you plan to use, then stay in the upper 50% or so of the volume range on your Squeezebox for practical listening.
    Last edited by pippin; 2019-05-15 at 04:12.
    ---
    learn more about iPeng, the iPhone and iPad remote for the Squeezebox and
    Logitech UE Smart Radio as well as iPeng Party, the free Party-App,
    at penguinlovesmusic.com
    New: iPeng 9, the Universal App for iPhone, iPad and Apple Watch

  3. #3
    Senior Member pippin's Avatar
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    Regarding measured curves, I believe Archimago has done measurements on this.
    ---
    learn more about iPeng, the iPhone and iPad remote for the Squeezebox and
    Logitech UE Smart Radio as well as iPeng Party, the free Party-App,
    at penguinlovesmusic.com
    New: iPeng 9, the Universal App for iPhone, iPad and Apple Watch

  4. #4
    Senior Member Archimago's Avatar
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    Hi guys... With regards to the Touch, no I have not checked out the volume control and noise characteristics. As pippin noted, I donít believe there would be any problem. It is a good basic question that perhaps can be demonstrated for folks worried about digital volume control. Iíve see this concern raised a number of times over the years.

    Will put it on my to-do list...
    Archimago's Musings: (archimago.blogspot.com) A 'more objective' audiophile blog.

  5. #5
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    Quote Originally Posted by Archimago View Post
    ...It is a good basic question that perhaps can be demonstrated for folks worried about digital volume control. Iíve see this concern raised a number of times over the years.

    Will put it on my to-do list...
    thank you !

  6. #6
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    Quote Originally Posted by Archimago View Post
    Hi guys... With regards to the Touch, no I have not checked out the volume control and noise characteristics. As pippin noted, I donít believe there would be any problem. It is a good basic question that perhaps can be demonstrated for folks worried about digital volume control. Iíve see this concern raised a number of times over the years.

    Will put it on my to-do list...
    Hi,

    how many items are before this one on your list ? what my I expect ? (for sure no complaints, but asking) thank you.

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