MQA is Vaporware

[sandyk]

48 minutes ago, Jud said:

 

Hmm, the old familiar discussion again.    Let's leave ultrasonics out of it - maybe there's some argument involving natural overtones, but all the discussion from Kal, firedog, you, and others is mostly correct on that score.  You'd need mics that record well into the ultrasonic (which do exist), speakers with useful response that high (I think there were some Sonys with diamond tweeters; not sure what else would qualify), and still it would be arguable whether just reproducing the audible result rather than re-creating the intermodulation from overtones at home would be as good or perhaps even better.

 

Nope, it seems to me the primary argument for hi res (if indeed it's better for otherwise equivalent masterings, another whole kettle of fish) is that you don't have to go through as much or as severe decimation filtering at the ADC end.

 

 Barry Diament's microphones are only 1dB down at 40kHz.

 When Sony first introduced SACD they also sold 100kHz tweeters to complement the initial extended frequency response of SACD.

Unfortunately, some amplifiers didn't like the relatively high Ultrasonic artifacts and there were quite a few reports at the time of some amplifiers burning out. The more relaxed filtering with 24/96 or 24/192 is clearly an advantage.

[sandyk]

2 minutes ago, Shadders said:

The fact that no hifi press has complained about class D high frequency issues, just shows you that it cannot be heard

Hi Richard

 Given the Hi Fi press's need for new products to review. and new advertiser revenue, that is hardly a recommendation for Class D.

 As far as I am concerned the earlier Class D amplifiers were mainly crap, with the better ones having far less distortion over the range to 20kHz , WAY too expensive compared with a decent Class AB 100W/Ch. amplifier for example.

 We have been through all of this before though, with numerous measurement graphs previously posted.

 

If you want a high quality recent 24/192 .wav file to compare with the Sound Forge 9 generated 16/44.1 version,  I will be happy to provide the links. You could always convert the 24/192 version to 16/44.1 yourself too.

 

Regards

Alex

 

 

 

[Shadders]

1 minute ago, sandyk said:

Hi Richard

 Given the Hi Fi press's need for new products to review. and new advertiser revenue, that is hardly a recommendation for Class D.

 As far as I am concerned the earlier Class D amplifiers were mainly crap, with the better ones having far less distortion over the range to 20kHz , WAY too expensive compared with a decent Class AB 100W/Ch. amplifier for example.

 We have been through all of this before though, with numerous measurement graphs previously posted.

 

If you want a high quality recent 24/192 .wav file to compare with the Sound Forge 9 generated 16/44.1 version,  I will be happy to provide the links. You could always convert the 24/192 version to 16/44.1 yourself too.

 

Regards

Alex

Hi Alex,

Thanks - the problem is that my Media player will limit the data rate on the optical to 48kHz. I have a Peter Gabriel 24/48 download from B&W which is excellent. I have some blu-ray discs which over HDMI allow for 96kHz, but i found these discs sound no different from a good RBCD. So, i have listened to high resolution - the increased bit depth seems to make the difference for myself.

 

Regards,

Richard.

[Rt66indierock]

22 hours ago, sandyk said:

 Hi Stephen

 I would respectfully suggest that we don't dilute this thread with silly arguments about amplifier bandwidth requirements, human hearing capabilities etc.

 In fact,  it may even be an advantage to roll off MQA encoded music, if we end up being stuck with it , (mainly due to greedy Entrepreneurs )  quite savagely from 22kHz to remove the possibility of their false information and added noise artifacts from being seen by the amplification chain at all. This may be hard to do with current filtering techniques though, without degrading the existing music.

 

 I would also gently remind you , that there are a large percentage of A.S. members who LOVE the high res formats, including 24/96 , 24/192, even 24/384, and especially the most recent DSD recordings with GENUINE music information well above 22kHz.

And even if most of the advantages come down to the more gentle HF  filtering possible with the high res formats, many members still prefer the high res version over the pathetic RBCD standard of 16/44.1.

 To mention as some do, the bandwidth of up to 48kHz , that is in this case a red herring, as 48kHz is normally only used for Audio on Videos, NOT with normal Music ONLY recordings.

 Yes, I do agree that the RBCD standard perhaps should have been 16/48kHz originally, but at the time they even had a lot of trouble getting 16/44.1 right.

 

If you believe that high res is likely to be of no advantage to you, then use the Format Comparison pages available on line to decide if there are likely to be of any benefit to you, however, I would also suggest that you verify this for yourself using a high quality pair of headphones with an extended frequency response to at least 40kHz, not loudspeakers that start to roll off sharply as they approach 20khZ.

 

 Feel free to remove this post after a short time period as it is OFF TOPIC, along with quite a few previous replies.

 

Kind Regards

Alex

 

Alex you got it wrong I want people to believe you need a highly resolving system to fully benefit from MQA and if they think the same way about high resolution music as listeners, well not that is not my problem.

 

As for high resolution itself I’ve been saying for years you will find high resolution a very difficult sell. Has anything thing changed? Not that I see. The Recording Academy in its Recommendations dated September 28, 2018 try to get delivery requirements of masters to include high resolution formats. But there is little reason to think high resolution will benefit artists. I have two standing challenges in audio. One is if you think high resolution will benefit artists prove it. Come to my office and lay your proof on my conference table in the Valley of the Sun. Nobody has.

 

And as far as headphones go, I will check some out this weekend at T.H.E. Show in Long Beach California this weekend. But I’ve written about ultrasonics in this thread. I don’t like them when I create them with a crash cymbal or welding so why should I like them with headphones?

[John Dyson]

1 hour ago, sandyk said:

 John

 The 33 page Data sheet that I attached is possibly the most detailed opamp data sheet that I have seen. It does show numerous graphs of distortion into various loads etc., but you are correct in that it doesn't show the input resistance value used.

 However, in practise they are prone to instability/oscillation problems when directly driving cable loads of 100pF or more without a series output resistor.

 

Years ago, I also had several of the National Data books that you referred to, but they are obsolete now due to much newer devices. 

 

Regards

Alex

LME49720.pdf 1.04 MB · 0 downloads

Pllleassse -- look at the document that I referred to -- note the various input/output conditions/impedances, etc.  Spec-sheets like the one that you attached do not handle several very important  characteristics (source impedance vs.  input impedance effects are a relatively significant effect on distortion, yet is almost always poorly specified.)   The moderately low source impedance case is NOT always real world.

Even JFETs can have significant loading on the source because of capacitance effects and unbalanced  +,- inputs.  Lower voltage noise are usually worse (because of the lower dynamic input impedance, and it varies.)  Higher voltage noise devices tend to be smaller geometry, and therefore lower capacitance.  Also, a high impedance input often runs at lower currents which will cause a little less apparent varying DC input resistance.  By far, the AC loading effects are the most poorly specified.  (Devices running at lower bias currents tend to have more voltage noise and less current noise, also smaller geometry devices tend to have higher intrinsic resitances which increase the voltage noise -- making them more useful at lower currents.  Super low noise BJTs tend to be large geometry -- because the specsmanship is usually about input voltage noise, even though current noise is more important for higher source impedances.)

 

The problem with the spec sheet generally is that they don't always give real-world curves.  For example, what is the distortion at 10kHz with a 10k source resistance and a 600ohm load, at 0.1V, 1V and 10V output AC, and gains of 1, 10, 100.  There are lots of conditions, where the spec sheets give an idea as to the performance, but it isn't always complete enough.

 

I did a quick scan of the specs -- think about an op-amp in non-inverting mode (therefore dependent on the matching between input transistors/network), and running gain of X, source impedance of 40kohms, (common mode input impedance is very high -- so 40kohms is possilble), and at frequencies between 1k through 100kHz (assuming that some miscreant audio source supplies lots of high frequency signal -- wanna make sure that the IMD doesn't reach back down to audio.)   Read the specs CAREFULLY...

 

Here is a problem -- what is the input capacitance?  Why do you want to know the input capacitance?  Because it varies with the signal and internal state of the circuit and feedback, etc.   When the signal varies, and you have a non-zero source resistance, that varying input capacitance causes distortion.  In fact, this varying input capacitance is worse because usually a non-inverting amplifier circuit isn't AC balanced on the input -- so there are all kinds of weird distortions based on the unbalance that leak into the design.

 

So, you have a circuit, with a relatively high impedance source, and no useful spec that works with a general case of input impedance.

 

The input impedance of the op-amp circuit varies vs signal/frequency/etc -- where is that specified?  Do you know that is a significant source of distortion in op-amp circuits?  The distortion in an actual circuit will be significantly worse than the specs because of these facts (and others.)

 

Again -- read that very interesting document, and note the missing information from the 'common' spec-sheet -- even the many page attempt-to-look-complete.  Working engineers know about the missing specs, and know about the need to do tests or require selected or special order parts...  Real world production design IS sometimes a cr*p shoot on complex devices.  (If they keep on making them for longer than a few years.)

Doing your own high quality BJT/JFET design is the best -- if you can...  Of course, in production, that isn't quite as practical as using a chip that you pray that you can keep on purchasing.

 

John

 

 

[esldude]

deleted

[esldude]

9 hours ago, Archimago said:

 

Yup. Speaking of vintage recordings from old tape machines... Here's HDTrack's Kind of Blue, "So What" (1959), in 24/96, FFT averaged over about a minute of audio to clarify the sonic content:

 

 

Notice it's essentially -95dBFS and lower noise from 21kHz onward. I see that HDTracks offers the 192kHz version as well. For $5.00 more of course... Not exactly good value IMO.

Would be interesting to filter out everything below 20 khz.  Slow the speed to 1/4th, and amplify what is left to listen to it.  Is it only tape noise up there or is anything whatsoever related to music.  I think it will be noise only. 

[Ishmael Slapowitz]

ZZZZZzzzzzzz...is it possible to get back on topic?

 

[sandyk]

1 hour ago, John Dyson said:

Pllleassse -- look at the document that I referred to -- note the various input/output conditions/impedances, etc.  Spec-sheets like the one that you attached do not handle several very important  characteristics (source impedance vs.  input impedance effects are a relatively significant effect on distortion, yet is almost always poorly specified.)   The moderately low source impedance case is NOT always real world.

Even JFETs can have significant loading on the source because of capacitance effects and unbalanced  +,- inputs.  Lower voltage noise are usually worse (because of the lower dynamic input impedance, and it varies.)  Higher voltage noise devices tend to be smaller geometry, and therefore lower capacitance.  Also, a high impedance input often runs at lower currents which will cause a little less apparent varying DC input resistance.  By far, the AC loading effects are the most poorly specified.  (Devices running at lower bias currents tend to have more voltage noise and less current noise, also smaller geometry devices tend to have higher intrinsic resitances which increase the voltage noise -- making them more useful at lower currents.  Super low noise BJTs tend to be large geometry -- because the specsmanship is usually about input voltage noise, even though current noise is more important for higher source impedances.)

 

The problem with the spec sheet generally is that they don't always give real-world curves.  For example, what is the distortion at 10kHz with a 10k source resistance and a 600ohm load, at 0.1V, 1V and 10V output AC, and gains of 1, 10, 100.  There are lots of conditions, where the spec sheets give an idea as to the performance, but it isn't always complete enough.

 

I did a quick scan of the specs -- think about an op-amp in non-inverting mode (therefore dependent on the matching between input transistors/network), and running gain of X, source impedance of 40kohms, (common mode input impedance is very high -- so 40kohms is possilble), and at frequencies between 1k through 100kHz (assuming that some miscreant audio source supplies lots of high frequency signal -- wanna make sure that the IMD doesn't reach back down to audio.)   Read the specs CAREFULLY...

 

Here is a problem -- what is the input capacitance?  Why do you want to know the input capacitance?  Because it varies with the signal and internal state of the circuit and feedback, etc.   When the signal varies, and you have a non-zero source resistance, that varying input capacitance causes distortion.  In fact, this varying input capacitance is worse because usually a non-inverting amplifier circuit isn't AC balanced on the input -- so there are all kinds of weird distortions based on the unbalance that leak into the design.

 

So, you have a circuit, with a relatively high impedance source, and no useful spec that works with a general case of input impedance.

 

The input impedance of the op-amp circuit varies vs signal/frequency/etc -- where is that specified?  Do you know that is a significant source of distortion in op-amp circuits?  The distortion in an actual circuit will be significantly worse than the specs because of these facts (and others.)

 

Again -- read that very interesting document, and note the missing information from the 'common' spec-sheet -- even the many page attempt-to-look-complete.  Working engineers know about the missing specs, and know about the need to do tests or require selected or special order parts...  Real world production design IS sometimes a cr*p shoot on complex devices.  (If they keep on making them for longer than a few years.)

Doing your own high quality BJT/JFET design is the best -- if you can...  Of course, in production, that isn't quite as practical as using a chip that you pray that you can keep on purchasing.

 

John

 

 

John

I am aware of many of the things you are saying and prefer discrete, BUT , I have had an Internet failure here now for several hours and it is too tedious to further reply to yours and others posts on this tiny  little mobile.

Alex

[John Dyson]

On 6/6/2019 at 8:46 PM, esldude said:

Would be interesting to filter out everything below 20 khz.  Slow the speed to 1/4th, and amplify what is left to listen to it.  Is it only tape noise up there or is anything whatsoever related to music.  I think it will be noise only. 

Yes -- it will be noise (imd/hd splats from the lower 20kHz & sometimes 'tones').

[Rt66indierock]

Back on topic little evidence of MQA at T.H.E. Show in Long Beach California day one.

[John_Atkinson]

7 hours ago, John Dyson said:

Yes -- it will be noise (imd/hd splats from the lower 20kHz & sometimes 'tones').

 

Analyses I performed 20 years ago showed that many recordings, even from analog sources, had music-related content  above 20kHz.

See https://www.stereophile.com/features/282/index.html

 

Note that one of the letters published in response to this article was written by Bob Stuart.

 

John Atkinson

Technical Editor, Stereophile

 

[Rt66indierock]

25 minutes ago, John_Atkinson said:

 

Analyses I performed 20 years ago showed that many recordings, even from analog sources, had music-related content  above 20kHz.

See https://www.stereophile.com/features/282/index.html

 

Note that one of the letters published in response to this article was written by Bob Stuart.

 

John Atkinson

Technical Editor, Stereophile

 

 

I have a reference to your article in a University of California paper. It should be pointed out Bob Stuart was just about to start losing what I consider real money shortly after his comment. 

[John Dyson]

2 hours ago, John_Atkinson said:

 

Analyses I performed 20 years ago showed that many recordings, even from analog sources, had music-related content  above 20kHz.

See https://www.stereophile.com/features/282/index.html

 

Note that one of the letters published in response to this article was written by Bob Stuart.

 

John Atkinson

Technical Editor, Stereophile

 

There are certainly some cases where there is 'music' up there, but most often, it is just distortion, tones, etc.   The distortion splats look just like music -- -I can create them at will if you want -- just break my DolbyA decoder to let it cause them again. BTW -- whatever music  up there is of such a VERY VERY low level that is meaningless when there is 'music.'   As soon as you add in the various forms of distortion, the 'music' is meaningless, and better just to remove it (it is a burden for the electronics, and cannot be heard -- PERIOD.)

 

Also, don't talk about 'vinyl' being able to reproduce above 20kHz -- it is so very contorted/distorted that the very small amount of meaningful music -- is damaged anyway.

 

Best to put on a competent engineering hat -- not so much a marketeer trying to benefit a 'cause'  $$$ of some kind. If the technically unneeded 'information'  (and actually burdensome) above 20kHz 'makes you feel good' -- I cannot discuss that. 

 

John

[Paul R]

2 minutes ago, John Dyson said:

There are certainly some cases where there is 'music' up there, but most often, it is just distortion, tones, etc.   BTW -- whatever music  up there is of such a VERY VERY low level that is meaningless when there is 'music.'   As soon as you add in the various forms of distortion, the 'music' is meaningless, and better just to remove it (it is a burden for the electronics, and cannot be heard -- PERIOD.)

 

Also, don't talk about 'vinyl' being able to reproduce above 20kHz -- it is so very contorted/distorted that the very small amount of meaningful music -- is damaged anyway.

 

Best to put on a competent engineering hat -- not so much a marketeer trying to benefit a 'cause'  $$$ of some kind. If the technically unneeded 'information'  (and actually burdensome) above 20kHz 'makes you feel good' -- I cannot discuss that. 

 

John

 

Hi John - 

There is plenty of music content above 20khz, and nope, it ain't distortion. Vinyl can reproduce it just fine.  Has been that way for ages. Not saying anyone can actually hear it, at least not directly. However, if you stick your paw in an ultrasonic record cleaner bath you are sure able to feel something. 😉

 

Can you be a little more specific about what you are talking about? 

[mansr]

26 minutes ago, Paul R said:

However, if you stick your paw in an ultrasonic record cleaner bath you are sure able to feel something.

Sure, but have you ever stuck your ear in one?

[Paul R]

2 hours ago, mansr said:

Sure, but have you ever stuck your ear in one?

Naw, but what would you expect your ear to hear at 35khz? Might clear out some ear wax...

 

[lucretius]

4 hours ago, John_Atkinson said:

 

Analyses I performed 20 years ago showed that many recordings, even from analog sources, had music-related content  above 20kHz.

See https://www.stereophile.com/features/282/index.html

 

Note that one of the letters published in response to this article was written by Bob Stuart.

 

John Atkinson

Technical Editor, Stereophile

 

 

Here, you are referring to ultrasonic overtones as music.  You are ending the argument by presupposing the existence of music.

 

[John_Atkinson]

3 minutes ago, lucretius said:

Here, you are referring to ultrasonic overtones as music.

 

Yes, the >20kHz content is correlated with the sounds of recorded musical instruments.  When the music stops the overtones disappear.

 

John Atkinson

Technical Editor, Stereophile

 

[Ralf11]

but is it euphonic?

[lucretius]

31 minutes ago, John_Atkinson said:

 

Yes, the >20kHz content is correlated with the sounds of recorded musical instruments.  When the music stops the overtones disappear.

 

John Atkinson

Technical Editor, Stereophile

 

 

First, does it have an effect on the audible range? Second, if it does have an effect, is it "musical"?

[fas42]

Every time I've looked at a track with guaranteed genuine above 20kHz content, it's either been incidental noises from objects in the recording environment being impacted, or buried in the depths of a big musical climax, that is, completely masked. Also, big, big, ultrasonic noisefloor; completely random, constant twitching of the waveform at above 20k frequencies - which may have a completely unintentional, and positive effect, in continually exercising the DAC circuitry.

[Paul R]

Or a trumpet, cymbal, piccolo, etc. 

[Sal1950]

13 hours ago, John_Atkinson said:

nalyses I performed 20 years ago showed that many recordings, even from analog sources, had music-related content  above 20kHz.

Ah, but can you hear it?

10 hours ago, Paul R said:

There is plenty of music content above 20khz, and nope, it ain't distortion. Vinyl can reproduce it just fine.

Great example, the CD-4 vinyl "carrier" 30khz was chosen since it's  inaudible in and of itself. 

[mcgillroy]

Guttenberg has an MQA-episode on his channel and it certainly ticks all the boxes: "white glove treatment for artists" (2:00) etc.

 

Also watch the Tidal-representatives reaction when Guttenbergs says "it is really true there is artists involvement in the final process" at 2:50. Comedy gold

 

The comments under the video are interesting too.