What Sample Rate Do We Really Need?

compact disc, dacs, mp3 players and streaming audio
NOYB
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Re: What Sample Rate Do We Really Need?

Post by NOYB » 02 Nov 2019 18:48

How have you determined that the RFI interference is from the DAC output noise and not from the DAC electronics?

poutrew wrote: ↑
02 Nov 2019 18:20
Erin1 wrote: ↑
25 Oct 2019 12:24
Simple answer:

The low pass filter in the output stage of the DAC will filter out the sharp edges of the stair steps resulting in a smooth analogue sine wave.

Note: only R2R DACs have "stair step" outputs. Newer Delta Sigma DACs don't have stair steps.

It isn't as straight forward as this when dealing with real world circuits that must obey physical law. If you are looking at the DAC output on a scope with a small bandwidth, you will see a nice, pretty sine wave output. But that is only because your scope cant resolve the higher order artifacts that a DAC introduces. Use a high bandwidth scope, and increase the timebase so you can, in effect, drill down into the output signal, and you will be able to see that the pretty output is still stairstep. True, the output filtering makes the output stair curved, but the discretized nature of the signal is still there. No amount of filtering will ever make the output waveform look totally analog. Depending on how high your scopes bandwidth goes, it's interesting to focus in on the output filtered part of the waveform and see all the messy artifacts the DAC introduces into the waveform as it attempts to create a 'clean' output. Now, does all of this really matter? Not to your ears, because some of these artifacts are super high frequency that can extend into the kilo - mega hertz range, and you can not hear it. But it does matter in terms of rfi - radio frequency interference. As a test, stick a portable am radio near the DAC chip when you turn it on and you will be able to hear the spurious crap your 'clean digital sound' actually does generate... lucky we don't have antenna for ears. :)

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Re: What Sample Rate Do We Really Need?

Post by Erin1 » 03 Nov 2019 06:03

poutrew wrote: ↑
02 Nov 2019 18:20

It isn't as straight forward as this when dealing with real world circuits that must obey physical law.
I know what you're saying is correct. If the scope has FFT functions you will see high frequency harmonics going out to 50Mhz. BUT, like you said we cannot hear it, so we probably should ignore it and not treat it as a problem. The lowest pulses will be at 176.4Khz (4x oversampling)
and we cannot hear them. πŸ™‚
So I don't think it's worth worrying about.
Do you think it's worth worrying about?

There are many electronic devices that can cause noise on a portable radio -plasma TVs, some computers, switch mode power supplies etc.

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Re: What Sample Rate Do We Really Need?

Post by Erin1 » 03 Nov 2019 06:30

Hanuman wrote: ↑
02 Nov 2019 11:32
My point is I've never regarded the analogue / digital video transition to be remotely relevant to the audio discussion, either in the studio or in the home. The film to digital camera transition is more relevant.
How interesting.
I personally think there is a huge relevance. What is interesting to me is how when people see the clarity of digital video they are very impressed with the amount of contrast, the accuracy of colour, and how that clarity allows them to see greater detail, and hence enhance their enjoyment.

Yet, some people when they hear digital audio which provides the same sorts of advantages as digital video complain that digital audio doesn't sound better.

It is from this line of thought which I have made mention of the link between digital audio and video.

Even film is not perfect, it can have some grainy qualites.

I think what people like about analogue sound and film is it's imperfections which can be regarded as artistic or poetic. Possibly making analogue audio and video more like a pleasant dream, rather than stark reality like digital.

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Re: What Sample Rate Do We Really Need?

Post by NOYB » 03 Nov 2019 07:15

Erin1 wrote: ↑
03 Nov 2019 06:30
Yet, some people when they hear digital audio which provides the same sorts of advantages as digital video complain that digital audio doesn't sound better.
I think there is a long list of contributors to this.
Just a few...

Mastering

The loudness war

CD pre-emphasis not being handled correctly

Turned off/tainted by poor early exposer

Security blanket (familiarity with how music sounded for so long)

The analog/digital gap size may be smaller than with video. Especially when going from standard def to high def too. So a significant resolution increase as well for video. Not as much so with audio. The previous analog equipment was already pretty good compared to the human auditory system capability. But video was nowhere close to human visual capability. Even with current hi res video still has a ways to go before exceeding the human visual system.

Psychological... bits can't be analog audio. Where as consumer home video was always somewhat more like digital in that it was and still is made up of pixels.

Some people don't know the difference between sounding better and sounding different. Some of them even interrupt the ringing that some ultra expensive speaker cables make with some amplifiers as being greater clarity.

We are more sensitive to audio than we are to video.

I'm sure everyone can come up with a lot more.

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Re: What Sample Rate Do We Really Need?

Post by Erin1 » 03 Nov 2019 12:31

Yes, that all seems correct.

NOYB Since you asked about sample rates, what have you concluded from this discussion?

Do you have an opinion?

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Re: What Sample Rate Do We Really Need?

Post by NOYB » 03 Nov 2019 13:26

I think there is likely some benefits from higher sample rates to reduce the LPF steepness and to also move it up away from the frequency band of interest to reduce artifacts being injected by the LPF. The time resolution of our auditory system perhaps would benefit some as well. These are pretty minimal but I think they do exist. Even though I will never consciously perceive it. But my interest was never about what we can or can't hear. But the technical goings on with the conversions.

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Re: What Sample Rate Do We Really Need?

Post by Erin1 » 03 Nov 2019 22:57

I think high sample rates are fine, and have some advantages over 44.1khz.
But, like everything in life, nothing is perfect, and high sample rates make very large files. This is really the only downside. I've done AB comparisons and didn't find enough of an advantage to bother recording at 192khz.
I record vinyl at 48khz, which gives a little more HF extension.

Although I do notice small improvements with high sample rates (with some music) I don't feel it's a big enough issue to get my knickers in a knot over it.
I think the mixing and mastering plays a bigger role in the overall sound.

Personally, I'm more interested in what people perceive, rather than the technical discussion.

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Re: What Sample Rate Do We Really Need?

Post by NOYB » 04 Nov 2019 00:00

I'm interested in what people perceive when they back it up with what is going on technically. For instance, a soapbox example, don't simply tell me a speaker cable is better because it sounds brighter and that is interpreted as greater clarity. Show what is causing the difference and that it is actually improved fidelity rather than degraded.

Speaker Wire - A History by Roger Russell
http://www.roger-russell.com/wire/wire.htm

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Re: What Sample Rate Do We Really Need?

Post by Hanuman » 04 Nov 2019 03:31

Erin1 wrote: ↑
03 Nov 2019 06:30
Hanuman wrote: ↑
02 Nov 2019 11:32
My point is I've never regarded the analogue / digital video transition to be remotely relevant to the audio discussion, either in the studio or in the home. The film to digital camera transition is more relevant.
How interesting.
I personally think there is a huge relevance. What is interesting to me is how when people see the clarity of digital video they are very impressed with the amount of contrast, the accuracy of colour, and how that clarity allows them to see greater detail, and hence enhance their enjoyment.
But there's too much going on in video processing to just ascribe the benefits to digital recording. I saw Sony's early analogue HD system in action in 1985 and its on-screen quality, off tape, was the equal of what we see now, better, even, than digital HD broadcasts due to the complete absence of compression. It wouldn't have held up over multiple generations, which is the real reason for digital recording. Back to the consumer side, Laserdisc (analogue) was also very high quality, better than off-air. DVD brought more than digital video into the home. It was also free of all PAL/NTSC encoding artefacts so quite a bit more going on than just a switch from analogue to digital.
Yet, some people when they hear digital audio which provides the same sorts of advantages as digital video complain that digital audio doesn't sound better.

It is from this line of thought which I have made mention of the link between digital audio and video.
I'm sure many of us on the forum are old enough to have lived through the transition to CD in the early-mid eighties. For whatever reason it just wasn't a good-sounding era, to my taste.
Even film is not perfect, it can have some grainy qualites.
That's exactly why I see the parallel. Film imaging is objectively, measurably inaccurate in a number of ways that digital is not but it still retains a following.
Last edited by Hanuman on 04 Nov 2019 04:24, edited 1 time in total.

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Re: What Sample Rate Do We Really Need?

Post by Hanuman » 04 Nov 2019 03:34

Erin1 wrote: ↑
03 Nov 2019 06:30
Hanuman wrote: ↑
02 Nov 2019 11:32
My point is I've never regarded the analogue / digital video transition to be remotely relevant to the audio discussion, either in the studio or in the home. The film to digital camera transition is more relevant.
How interesting.
I personally think there is a huge relevance. What is interesting to me is how when people see the clarity of digital video they are very impressed with the amount of contrast, the accuracy of colour, and how that clarity allows them to see greater detail, and hence enhance their enjoyment.
But there's too much going on in video processing to just ascribe the benefits to digital recording. I saw Sony's early analogue HD system in action in 1985 and its on-screen quality, off tape, was the equal of what we see now, better, even, than digital HD broadcasts due to the complete absence of compression. It wouldn't have held up over multiple generations of course, which is the real reason for digital recording. Back to the consumer side, Laserdisc (analogue) was also very high quality, better than off-air, but it was encoded colour (PAL or NTSC). DVD brought more than digital video into the home. It was also free of all PAL/NTSC encoding artefacts, so quite a bit more going on than just a switch from analogue to digital. We did have an encoded-colour pro digital format (D2) which had a short moment of relevance before sinking into obsolescence very quickly proving that just digital alone was not enough in the video world.
Yet, some people when they hear digital audio which provides the same sorts of advantages as digital video complain that digital audio doesn't sound better.

It is from this line of thought which I have made mention of the link between digital audio and video.
I'm sure many of us on the forum are old enough to have lived through the transition to CD in the early-mid eighties. For whatever reason it just wasn't a good-sounding era, to my taste.
Even film is not perfect, it can have some grainy qualites.
That's exactly why I see the parallel. Film imaging is objectively, measurably inaccurate in a number of ways that digital is not but it still retains a following.
I think what people like about analogue sound and film is it's imperfections which can be regarded as artistic or poetic. Possibly making analogue audio and video more like a pleasant dream, rather than stark reality like digital.
Yes, its distortions can be interesting and pleasing but I wouldn't go as far as "pleasant dream" because because it can be crisp and harsh if needed. Technically, you wouldn't use it any more. I was interested to read that for "The Irishman" all the de-aged sequences were shot digitally while the remainder of the movie was film.

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Re: What Sample Rate Do We Really Need?

Post by Erin1 » 04 Nov 2019 04:18

Hanuman, I will defer to your expertise with video. Your points are understood.
I keep saying, there is nothing perfect in this world. Perhaps all anyone can do is enjoy the moment fully, which may be as close to perfection as we can get.

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Re: What Sample Rate Do We Really Need?

Post by Hanuman » 04 Nov 2019 04:21

NOYB wrote: ↑
03 Nov 2019 07:15
The previous analog equipment was already pretty good compared to the human auditory system capability. But video was nowhere close to human visual capability. Even with current hi res video still has a ways to go before exceeding the human visual system.
Good point.
Psychological... bits can't be analog audio. Where as consumer home video was always somewhat more like digital in that it was and still is made up of pixels.
Another good point although, to be pedantic, purely analogue video is sampled in only one spatial dimension due to scanning whereas a discrete pixel is very much a digital concept. But it's a good point to make that even analogue video is broken up into discrete pieces to some extent.

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Re: What Sample Rate Do We Really Need?

Post by Vinylfreak86 » 04 Nov 2019 10:13

If we are talking about video and digital technology, I can say only this. Majority of new movies, which you can watch at cinema are digitally recorded by Sony Cinealta or Arri Alexa and similar things. It is not bad. But when I was watching the last movie from Tarantino - Once upon a time in Hollywood, which was 100% analog shot on 35 mm film, I was amazed at the quality of picture and vivid colours that I could see. Yes, but at the end Tarantino`s movie was digitized for playback in a digital cinema.

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Re: What Sample Rate Do We Really Need?

Post by Hanuman » 04 Nov 2019 12:04

Vinylfreak86 wrote: ↑
04 Nov 2019 10:13
But when I was watching the last movie from Tarantino - Once upon a time in Hollywood, which was 100% analog shot on 35 mm film, I was amazed at the quality of picture and vivid colours that I could see. Yes, but at the end Tarantino`s movie was digitized for playback in a digital cinema.
You can rest assured that there'll be film intermediates and prints as well. I believe that Tarantino owns a cinema somewhere in LA with a film projector.

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Re: What Sample Rate Do We Really Need?

Post by Erin1 » 05 Nov 2019 11:21

I read recently of a native tribe who had never seen a photograph. When they were handed a photograph they would feel the paper, and smell the paper, tear the paper - but they could not recognise the person in the photo because to them it was not the person, and it was unrecognisable.
They just couldn't even see the person.