High Resolution Audio: Does It Matter?

[Blumlein 88]

I would have hoped that everyone reading here has at least enough inate curiosity that they've done a little research


I found a paper dating back some years concerning rigorous measurements (done in Germany) of scrape-flutter frequencies, and it gave figures by tape type/manufacturer, interestingly. The figures were, IIRC, 720-960 Hz, but I assume tape speed has a bearing, and I don't remember what they used.

Plangent say they find timing errors at frequencies right up to c. 2kHz.

I've made several attempts to explain why the smeared HF (in particular) is made considerably worse by the effects of 44.1's steep, low-pass filtering, close to the audio band, but this is (despite being measurable) "inaudible" according to most respondents here.

Scrape flutter will cause sidebands around tones and as it is a resonance of the tape system would also cause a tone at the flutter frequency itself. The levels are going to be fairly low. 1% meaning sidebands of 1% the amplitude of the main tone would be very high levels of this. So your 44.1 khz system responds to 20 khz, and has a stopband at 22.05 khz. Few tape machines have good output beyond 18 khz. But let us say it does. So you have 2 khz scrape flutter which would create sidebands around a high level 20 khz tone (which usually doesn't happen). So some tones at 18 khz captured by the digital recording. Tones at 22 khz would be filtered out. How is this smeared HF? If you recorded at 96 khz, then you get the 18 khz and 22 khz sidebands. Again these are probably more than 40 db down in level versus the music at 20 khz. As few tape machines are good enough past 18 khz to have the sidebands above the noise floor of high frequency tones it will still be a basic non-issue even at 44.1 khz. The upper sideband of an 18 khz tone is 20 khz, and that is really all you'll see in very nearly all tapes recorded.

 

[Mark S.]

Scrape flutter will cause sidebands around tones and as it is a resonance of the tape system would also cause a tone at the flutter frequency itself. The levels are going to be fairly low. 1% meaning sidebands of 1% the amplitude of the main tone would be very high levels of this. .......

"Sidebands around tones", hence a haze of spuriae around/throughout the entire signal. And BTW, wow and flutter have frequencies but no "amplitude".

ETA >> a matter of semantics, perhaps, but once a frequency (a "tone") is modulated by another one (wow/flutter) it no longer exists in the resulting signal - it becomes a range of "tones" of +/- the modulating (wow/flutter) frequency.

ETA 2 >> 'sidebands' created by scrape-flutter in the 100's of Hz or even >1 KHz range, inflicted on low-level, HF content will be a lot higher than "1%". A LOT higher.

 

[solderdude]

Wow and flutter can have both frequencies and amplitudes.
The amplitude of the occurrence is how much % the speed varies (ultimately how much the frequency shifts) and the frequency part is how often the speed varies in time.
For instance the variance could be 1 deviation cycle per second, or 100 deviation cycles per second (the frequency part)
That variance could be 0.1% or 1% in frequency shift which is the amplitude.

 

[Mark S.]

Wow and flutter can have both frequencies and amplitudes.
....

No, they don't.

ETA > wow/flutter has to be expressed in some way, and the convention, using various 'weightings', is as a percentage. An W/F figure for, say, a 15 ips 1/4" tape made and played back on an otherwise perfect machine, but which imposed 1kHz scrape-flutter would be absolutely minute.

 

[Mark S.]

And round we go, back to the original question (and thread topic) - is there any point in high sampling-rate digital audio (and inferentially, can it better reproduce analogue recordings)?

The cutting lathes and record players used for vinyl playback, when properly designed and set up, exhibit almost no flutter at all. Drift and wow, at < 100hz, yes.

Vinyl playback didn't exacerbate the effects of the scrape-flutter often present on the tapes.

The same wasn't and isn't true of Red Book because of the further artifacts it inflicts with its steep, low-pass digital filtering.

I'm not saying ALL analogue tapes suffer from scrape-flutter. Those that don't can and do sound superb captured at 44.1, but I believe that a large part of the reason for the "flat", "lifeless" sound many CD releases have exhibited over the years is because they don't reproduce the "imperfect" analogue tapes faithfully (!).

That famous disclaimer has an added poignancy about it now;

The music on this Compact Disc was originally recorded on analog equipment. We have attempted to preserve, as closely as possible, the sound of the original recording. Because of its high resolution, however, the Compact Disc can reveal limitations of the source tape.

 

[andreasmaaan]

The same wasn't and isn't true of Red Book because of the further artifacts it inflicts with its steep, low-pass digital filtering.

There is just no evidence for this statement, or at least none that's been offered here.

We've talked around it for pages and pages, but when it comes to playback (as distinct from processing), nobody has been able to offer any reasonable theory or experimental evidence as to how a low-pass filter which is completely outside the audio band could possibly generate audible artefacts, nor how it could audibly exacerbate artefacts already present in an analogue recording from which it was derived.

 

[Wombat]

I'm intrigued! At approximately what time is the effect?

7 seconds. the word 'from'.

I played all of my CD tracks(10) of Ruby Tuesday and the word 'from' is at 5 seconds. All sound like the video you posted except the two different matrix numbered original London label CD pressings of Between The Buttons. There the warble was very slightly noticeable whereas on the video and all the later CDs not so.
Unfortunately my TTs are not currently set up so I can't check the original LP and 7inch single. My recollection is that the warble was similar to that produced when the tape is briefly and lightly touched, slows momentarily, and then flutters as it regains normal speed.

The original CD releases were remastered versions and several remasters followed over the years with variations of those releases in Japan. The warble may have been edited. I distinctly remember a sound as though the tape had fluttered on my vinyl versions. It was not unusual in the 60s for variations to be made to Stones LPs in subsequent pressings/issues..

Until I can check my vinyl versions, I will leave my observation as uncorroborated.

 

[Mark S.]

There is just no evidence for this statement, or at least none that's been offered here.

We've talked around it for pages and pages, but when it comes to playback (as distinct from processing), nobody has been able to offer any reasonable theory or experimental evidence as to how a low-pass filter which is completely outside the audio band could possibly generate audible artefacts, nor how it could audibly exacerbate artefacts already present in an analogue recording from which it was derived.

If people want to believe that audio technology reached its apotheosis with Red Book / 16/44.1, that it is "perfect" (or "perfect enough"), a veritable gift from the gods, and that makes them happy, far be it from me .........

 

[andreasmaaan]

If people want to believe that audio technology reached its apotheosis with Red Book / 16/44.1, that it is "perfect" (or "perfect enough"), a veritable gift from the gods, and that makes them happy, far be it from me .........

I don't "want" to believe that. It's just the most rational belief given the evidence.

 

[Mark S.]

I don't "want" to believe that. It's just the most rational belief given the evidence.

Well, I guess those Talking Heads albums I've been listening to in 24/96 sound so much more spacious and atmospheric to me than any CD release (and more like I remember them on vinyl) because of my over-active imagination/confirmation bias/gullibility.

Thanks for bursting my bubble, you heartless b'strd

 

[andreasmaaan]

Well, I guess those Talking Heads albums I've been listning to in 24/96 sound so much more spacious and atmospheric to me than any CD release (and more like I rememer them on vinyl) because of my over-active imagination/confirmation bias/gullibility.

Thanks for bursting my bubble, you heartless b'strd

That, or mastering differences.

I very much approve of your choice of music, however

 

[Mark S.]

That, or mastering differences.

I very much approve of your choice of music, however

Salut. The HDTracks versions are very good (mostly).

 

[derp1n]

Well, I guess those Talking Heads albums I've been listening to in 24/96 sound so much more spacious and atmospheric to me than any CD release (and more like I remember them on vinyl) because of my over-active imagination/confirmation bias/gullibility.

Which tracks would you say sound particularly good compared to the CD releases? I'd like to try for myself.

 

[andreasmaaan]

Btw, I wouldn't say "over-active" imagination or "gullibility" - it makes it sound like it is not absolutely bog standard normal to be susceptible to these things...

 

[Blumlein 88]

No, they don't.

ETA > wow/flutter has to be expressed in some way, and the convention, using various 'weightings', is as a percentage. An W/F figure for, say, a 15 ips 1/4" tape made and played back on an otherwise perfect machine, but which imposed 1kHz scrape-flutter would be absolutely minute.

If it is a frequency that results in no amplitude there is nothing there. It is minute, and according to the industry when reel tape was king, scrape flutter wasn't very audible at all.

 

[Blumlein 88]

And round we go, back to the original question (and thread topic) - is there any point in high sampling-rate digital audio (and inferentially, can it better reproduce analogue recordings)?

The cutting lathes and record players used for vinyl playback, when properly designed and set up, exhibit almost no flutter at all. Drift and wow, at < 100hz, yes.

Vinyl playback didn't exacerbate the effects of the scrape-flutter often present on the tapes.

The same wasn't and isn't true of Red Book because of the further artifacts it inflicts with its steep, low-pass digital filtering.

I'm not saying ALL analogue tapes suffer from scrape-flutter. Those that don't can and do sound superb captured at 44.1, but I believe that a large part of the reason for the "flat", "lifeless" sound many CD releases have exhibited over the years is because they don't reproduce the "imperfect" analogue tapes faithfully (!).

That famous disclaimer has an added poignancy about it now;

The music on this Compact Disc was originally recorded on analog equipment. We have attempted to preserve, as closely as possible, the sound of the original recording. Because of its high resolution, however, the Compact Disc can reveal limitations of the source tape.

You seem to have a bent idea of all this which does not square with how things work.

And first off, the quote at the end of your post is an indication CD was of superior fidelity to tape and would therefore reveal tapes inadequacies. That disclaimer was about tape hiss.

The idea scrape flutter interacts with 44.1 filtering to be a large part of the reason for 'lifeless' sound is wrong-headed guessing on your part. Considering how the mediums work it simply makes no sense. What interaction with scrape flutter would cause this effect? The answer is only ultrasonics or near ultrasonics would react with filtering of CD, and it wouldn't cause any type of sound over the rest of the audible spectrum. Scrape flutter adds tones that aren't supposed to be there. Where those added frequencies occur is around the original frequencies. The filter isn't going to mess with lower frequencies and the upper ones are going to be attenuated not accentuated. Nor is there some 'smearing' from that interaction across the rest of the band.

I don't know what you listened to which gave you this firmly held idea, but you really should let it go. It isn't the answer. It simply doesn't add up.

 

[Blumlein 88]

Well, I guess those Talking Heads albums I've been listening to in 24/96 sound so much more spacious and atmospheric to me than any CD release (and more like I remember them on vinyl) because of my over-active imagination/confirmation bias/gullibility.

Thanks for bursting my bubble, you heartless b'strd

They are surely a different mastering. Which Talking Heads albums do you have in 24/96?

 

[JJB70]

If it is a frequency that results in no amplitude there is nothing there. It is minute, and according to the industry when reel tape was king, scrape flutter wasn't very audible at all.

I was struggling with that, you can only measure a frequency if there is also some amplitude, if there is no amplitude then there is nothing there. Obviously you can calculate critical frequencies for structures and stuff regardless of whether there is any excitation but that is something very different.

 

[solderdude]

ETA > wow/flutter has to be expressed in some way, and the convention, using various 'weightings', is as a percentage.

That's exactly what I said. There is an amplitude and it is expressed in %. It IS an amplitude none the less.
The fact that you (and the convention) don't call it an amplitude doesn't make it less of an amplitude.

amplitude definition:
The amplitude of a periodic variable is a measure of its change over a single period (such as time or spatial period). There are various definitions of amplitude, which are all functions of the magnitude of the difference between the variable's extreme values.

Then you can apply all the weightings one wants and call it a percentage but it still IS an amplitude.

 

[Blumlein 88]

Maybe this is phantom flutter. The tape sticks, releases, flutters at ultrasonic frequencies, and stops all between those long 44.1 khz samples. There are nearly 23 microseconds between them. So for CD they have no amplitude. For 384 khz, they have amplitude and therefore you don't hear them negatively????? No something still isn't right. It's like a Rubik's cube or something.