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Digital file noise and distortion

Rjharle

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Prior to the digital age there were all kinds of specs to look at to determine if your audio equipment would add noise to the recording like turntable rumble, wow, flutter, tape deck hiss, preamp/amplifier hum, THD. So if your music presentations were noisy or distorted you could for the most part identify the cause. Today in the digital age we have THD, jitter, timing, and filters. So when a file doesn't sound right like it has changed from the original to too many highs and lows and not enough mid or the instruments don't sound right what is the problem.

When analog is changed something is added to the recording, the electrical signal get distorted or a noisy recording (pops clicks etc.) When a digital file becomes a problem what happened. A song is created in a stream is 1s and 0s and then formatted into an FLAC, WAV, MP3 where it sits on a medium until played. Then a digital player cues up where the song is then streamed ( 1s and 0S ) into a DAC. The DAC feeds an analog signal into the preamp > amp > speakers. Let's assume the analog signal is not the problem i.e. the preamp out are fine. What in the digital section could cause the song to change? What changes the bits and bytes (1s and 0s) to alter the music? Where would I look to get the music back to sound as it should?

Since I'm limited in my understanding of digital processing please, if possible, keep the answers simple.
 

levimax

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Usually if something is broken with digital playback it is obvious like skips or clicks or it just won't play. Outside of DSP / tone controls being inadvertently changed I don't think anything would change the "sound" of digital playback except your mood.
 
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Rjharle

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Usually if something is broken with digital playback it is obvious like skips or clicks or it just won't play. Outside of DSP / tone controls being inadvertently changed I don't think anything would change the "sound" of digital playback except your mood.
Putting my mood aside; are you saying all DSPs sound the same, unless broken, and their processing is always accurate? All timing and filters don't vary from DAC to DAC?
 

levimax

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Putting my mood aside; are you saying all DSPs sound the same, unless broken, and their processing is always accurate? All timing and filters don't vary from DAC to DAC?
What I am saying is that if you are hearing changes maybe your DSP settings (if you are using DSP for room correction or the like) got changed/ got turned off inadvertently. DAC filters do vary somewhat but even "radical" filters like NOS have only very subtle audible effects if any.
 

Pluto

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If there is a device in the system intended to change the sound, then clearly there is little accounting for what it might actually do.

Most decent, modern DACs sound fairly similar. To get this into perspective, the difference between two arbitrary $x record players or two arbitrary $y pairs of speakers is likely to be far greater than the difference between to arbitrary $z DACS, especially if the latter are both designed and made within the last three or four years.
 
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Rjharle

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What I am saying is that if you are hearing changes maybe your DSP settings (if you are using DSP for room correction or the like) got changed/ got turned off inadvertently. DAC filters do vary somewhat but even "radical" filters like NOS have only very subtle audible effects if any.
Thank you >> I think you are saying that once the digital content is entered onto a medium there is nothing in the digital chain to adversely change the playback of the recording until it reaches analog.
 
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DVDdoug

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Putting my mood aside; are you saying all DSPs sound the same
DPSs, NO! That's Digital Signal Processing and it's supposed to change something. Unless you are just resampling or something like that, and then the sound doesn't normally change as long as you stay above "CD quality"

All timing and filters don't vary from DAC to DAC?
You might be able to measure a difference but normally you won't hear a difference.

You mentioned MP3. MP3 is lossy compression (data is thrown-away to make a smaller file) so of course that can damage the sound. But at high-quality settings an MP3 often sounds identical to the uncompressed original (in a proper blind listening test). The ability to hear compression artifacts depends on the program material (some audio compresses easier than others) and the listeners ability to hear the artifacts. The equipment isn't much of a factor, but headphones help if your trying to hear a defect (or a difference).

Take a look at this. He explains the parameters that affect sound quality - Noise, frequency response, and distortion, and "time related effects" that don't happen in the digital domain or in the electronics.
 
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Rjharle

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If there is a device in the system intended to change the sound, then clearly there is little accounting for what it might actually do.

Most decent, modern DACs sound fairly similar. To get this into perspective, the difference between two arbitrary $x record players or two arbitrary $y pairs of speakers is likely to be far greater than the difference between to arbitrary $z DACS, especially if the latter are both designed and made within the last three or four years.
I was not referring to an intended effect. I was hoping that if there was something in the digital playback chain that wasn't built as well (quality) or out of calibration that someone would tell me what to listen for.
 

Kijanki

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Timing jitter of D/A clock might create additional frequencies not present in original signal/data. These frequencies are audible in spite of very small level, being not harmonically related to root frequency. For instance, DAC plays pure 1kHz tone, but D/A clock moves back and forth in time (jitter) 60 times a second (likely result of 60Hz electrical noise). DAC will produce 1kHz and many additional frequencies (sidebands) spaced 60Hz apart. Amplitude of these frequencies will be proportional to amount time variation (jitter). The only two closest, 940Hz and 1060Hz will likely be audible. With multiple input frequencies (music) there will be a lot of these extra frequencies - basically a noise added, audible only when signal is present. Since it is not audible without signal, the only manifestation of its presence is lack of clarity (often extra brightness, loss of imaging etc).
 

Chrispy

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I was not referring to an intended effect. I was hoping that if there was something in the digital playback chain that wasn't built as well (quality) or out of calibration that someone would tell me what to listen for.
You don't have a problem particularly but are looking to see if there is one?
 

LTig

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I was not referring to an intended effect. I was hoping that if there was something in the digital playback chain that wasn't built as well (quality) or out of calibration that someone would tell me what to listen for.
As long as the digital data are only transferred from one device to the next sound quality either does not change at all, or in case of a broken transport sound is either partially interrupted or just dead silent.

In case of DSP sound may get clipped if the processing is not proper implemented or the settings are wrong (e.g. you want to enhance low frequencies and the processing pipeline has not enough digital headroom).
 
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Rjharle

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You don't have a problem particularly but are looking to see if there is one?
I'm putting together a digital chain that may have issues, and I'm hoping to be able to identify a weak link should it happen. Here is what I'm looking to put together. For many reasons I cannot use an app for file management, so I have to come up with a way to use a handheld remote.

For file storage and management (Kodi Plex) Nvidia Shield TV Pro HDMI (out) > HDMI audio extractor I2s or SPDIF > Matrix Audio Element I > Anthem RCA or XLR input. The HDMI will carry the video to the screen. Once it is together and if it didn't sound correct I would need to know what to do. Please don't say buy a cellphone. P.S the Shield only has one HDMI out.
 
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Chrispy

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Sounds convoluted. The hdmi can't just connect to the Anthem? I'd just hook it up then worry about anything that sounds odd. Generally not fussy like something like tape or vinyl. Can't help you with the remote, although if the gear is all in a universal remote's data base or something....
 

BDWoody

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tonycollinet

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Timing jitter of D/A clock might create additional frequencies not present in original signal/data. These frequencies are audible in spite of very small level, being not harmonically related to root frequency. For instance, DAC plays pure 1kHz tone, but D/A clock moves back and forth in time (jitter) 60 times a second (likely result of 60Hz electrical noise). DAC will produce 1kHz and many additional frequencies (sidebands) spaced 60Hz apart. Amplitude of these frequencies will be proportional to amount time variation (jitter). The only two closest, 940Hz and 1060Hz will likely be audible. With multiple input frequencies (music) there will be a lot of these extra frequencies - basically a noise added, audible only when signal is present. Since it is not audible without signal, the only manifestation of its presence is lack of clarity (often extra brightness, loss of imaging etc).
Measurements of well designed dacs repeatedly show that any jitter artefacts are well below the levels of audibility.
 
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freemansteve

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A key point about any DAC is the "A" part... Whether audible or not, the analogue parts, which are not insubstantial by the time you get to a line-level signal, have potential for their own SINAD.
 

BDWoody

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A key point about any DAC is the "A" part... Whether audible or not, the analogue parts, which are not insubstantial by the time you get to a line-level signal, have potential for their own SINAD.

What does that mean?
 
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freemansteve

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What does that mean?
It means a DAC has analogue circuitry (by definition). Implementations vary. Some will have more noise and distortion than others. This all adds into the chain from files to speakers.
 

BDWoody

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It means a DAC has analogue circuitry (by definition). Implementations vary. Some will have more noise and distortion than others. This all adds into the chain from files to speakers.

Isn't that why we measure them?
 
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