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  1. #1
    Senior Member pippin's Avatar
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    How Replay Gain Works

    Quote Originally Posted by callesoroe View Post
    It is a fact that almost all DAC's do not sound good with clipped signals. And this is what happens when recordings are mastered way to loud.
    No, however often you repeat it, it is wrong.
    If your mastering is mastered so loud that it clips no volume, gain or whatever change can get the signal back, it broken, you've got just noise, if you play it less loud it will still be noise.

    Using replay gain you turn Down the heavy mastered recordings, and NO clipping comes to your DAC..... And it just sounds better....
    If this works it means your DAC is fundamentally broken because it doesn't even meet one of it's minimum design specification which is to be able to handle maximum volume samples. These samples will be there all the time, even without dynamics compression and your DAC will then clip, too.
    Life is too short to listen to a broken DAC, get a different one, every 2$-DAC has to be able to do this.

    Actually constant high-volume signals are not even very complex. A permanent maximum-volume-signal is the most boring and most easy to handle signal ever, high dynamic range is more complex for the DAC.

    This is not analog signal processing where people were mastering music all the time to go _beyond_ the specification which meant you could get clipping when playing that at high volume or even within your processing change. You can't master _beyond_ maximum in digital signal processing (or you get something permanently broken) and each DAc has to be able to cope with the maximum signal.

    So if your clipping indicator goes up at full volume and does not when you apply replay gain, get a different DAC, it's broken. It's as simple as that. Most DACs even have plenty of range they can handle above the maximum values because that way you can avoid nonlinearities at the end of the range, clipping must not happen in a DAC.
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  2. #2
    Senior Member Mnyb's Avatar
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    I think it's when you have several consecutive samples of 0dB IE like say 10 full 16bit word lined up together . One 0dB peak is not a problem .

    Yes some CD are deliberately digitally clipped too on top of the loudness war compression .

    There are some treads on hydrogen audio about this and some old research white paper I can't seem to find where this is shown to happen in some consumer CD players .
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  3. #3
    Senior Member Mnyb's Avatar
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    Sorry my Google fu is bad but we had this discussion before on this forums to and there is a decades worth of discussion on hydrogen audio . The gist is that a full scale signal is ok for a DAC chip but may not be for an interpolation process like how they may be done in oversamplers or filters .
    Similar to how I assume some lossy adio codecs apply some clever gain scheme to to clip the output .
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  4. #4
    Senior Member Mnyb's Avatar
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    Found my own post with some links.

    http://forums.slimdevices.com/showth...e-loudness-war
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  5. #5
    Senior Member Julf's Avatar
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    Quote Originally Posted by Mnyb View Post
    I think it's when you have several consecutive samples of 0dB IE like say 10 full 16bit word lined up together . One 0dB peak is not a problem
    Yes, that's what I alluded to in one of my first answers to callesoroe's misconceptions. Badly designed DACs might not be able to handle the over-0-db peaks that result from interpolation (not related to compression or "loudness wars"), but the fix is simple - just turn down the volume a bit.

    Yes some CD are deliberately digitally clipped too on top of the loudness war compression.
    Yes, but that can not be magically undone with replay gain (or any other gain adjustment).
    "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

  6. #6
    Senior Member Julf's Avatar
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    Quote Originally Posted by callesoroe View Post
    It is a fact that almost all DAC's do not sound good with clipped signals.
    It is my experience that anything that starts with "it is a fact that" usually isn't.

    Using replay gain you turn Down the heavy mastered recordings, and NO clipping comes to your DAC..... And it just sounds better....
    Let me repeat - if the signal is already clipped, replay gain won't magically undo the clipping. All replay gain does is adjust the gain. If your DAC clips with a signal that is too loud, it is badly designed, but the situation can be easily fixed by turning the gain/volume down by a little - that is all replay gain does, too.

    It is very visable on my system. When playing a loudness recording the VU meters on the Transporter bangs to the buttom, and The clipping indicator on my Tact
    lights up all the time.......
    Turning on replay gain VU meters are max at 0 db and mostly wide under. And the clipping indicator never lights up.
    I rest my case....... I can see and hear what happens.....
    No, you can see and hear what you *think* happens. What happens when you use replay gain is that the gain is reduced a bit - that is what you see on the VU meters, but you could have done the same by turning down the volume a little. The clipping indicator just detects "full scale" samples - so if you (or replay gain) reduce the volume, the clipping peaks are at a slightly lower level, and not detected by the Tact clipping indicator - but you haven't removed any of the clipping, just turned down the volume.

    Clipping can be an issue with replay gain - because replay gain can *cause* clipping as a result of the gain adjustment done by replay gain. So replay gain can never remove clipping that is already in the signal, but it can cause additional clipping.
    "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. #7
    Senior Member Mnyb's Avatar
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    Quote Originally Posted by Julf View Post
    Yes, that's what I alluded to in one of my first answers to callesoroe's misconceptions. Badly designed DACs might not be able to handle the over-0-db peaks that result from interpolation (not related to compression or "loudness wars"), but the fix is simple - just turn down the volume a bit.



    Yes, but that can not be magically undone with replay gain (or any other gain adjustment).
    My references in my old tread is old , but when company's like benchmark did not fix this until 2013 what gives for other brands .

    Misconception . I don't think you can say that all DAC's have this problem but an unknown ratio of them do have this problem but are they really badly designed ? In retrospect they are bad designs , but the signals presented by today's music is not " meant to be" if you ask some old school audio engineer ? What gives ?

    1. Turn down the volume anyway you want replaying is one way it gives typically -10dB or use the volume control .

    2. I would love to see test similar to those done in TC aes papers done to more recent DAC or some of the squeezebox models .

    3. You can use an unfiltered nos DAC sans interpolation filters :P but give many any "bad" DAC instead and I happily employ -6dB digitally .
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  8. #8
    Senior Member Mnyb's Avatar
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    RG clipping by the rare album that actually gives positive gain ? Is that not fixed in LMS there was a bug report about that ?

    Yes a constant volume adjustment might be more predicable . And we a have a fixed volume plugin somewhere if it's updated ?
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  9. #9
    Senior Member Julf's Avatar
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    Quote Originally Posted by Mnyb View Post
    Misconception . I don't think you can say that all DAC's have this problem but an unknown ratio of them do have this problem but are they really badly designed ? In retrospect they are bad designs , but the signals presented by today's music is not " meant to be" if you ask some old school audio engineer ? What gives ?
    If you ask a really old school audio engineer, he (invariably a he) would have said that Jimi Hendrix' music was not "meant to be" - all that horrible distortion!

    Intersample interpolation is not caused by overly compressing the signal - but simply by exceeding the maximum signal amplitude limit. You could cause it by a single, uncompressed sine tone that has too much amplitude for your digital channel. That is why Philips actually specified a lower-than-full-signal limit for the original CD specification, but very quickly gave up on trying to enforce it.


    But let's be clear - we all (well, except for callesoroe) agree that the simple solution is to turn down the valume/gain a little bit, and that is all that replay gain does.

    3. You can use an unfiltered nos DAC sans interpolation filters :P but give many any "bad" DAC instead and I happily employ -6dB digitally .
    There are no totally unfiltered NOS DACs - the filtering just happens somewhere further down the chain, and if the components down he chain can't handle the signal amplitude, you still get clipping.
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  10. #10
    Senior Member Mnyb's Avatar
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    Quote Originally Posted by Julf View Post

    There are no totally unfiltered NOS DACs - the filtering just happens somewhere further down the chain, and if the components down he chain can't handle the signal amplitude, you still get clipping.
    yes but that be "good" clipping from tubes or somesuch )

    yes i do understand that it is about the level .

    But a way to actually get a bunch of 0dB samples together is the way we master these days almost everything is very close to max . it's not like in old recording thats it's once every 2 minutes or less when the drummer hit's a snare unusually hard (for example ) but rather all the time .
    So when the producer maxes the volume suddenly it's more or less constant clipping .

    yes phillips was rigth spare a couple of dB when producing CD's
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