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MQA is Vaporware

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Incidentally, FWIW,not so long back Teresa couldn't stand RBCD, as something about it irritated her, but high res versions didn't .

 


"If you can't hear the difference between an original CD and a copy of your CD,

you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

PROFILE UPDATED 18-06-2019

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15 minutes ago, lucretius said:

Overtones are overtones. If you cut the ultrasonic overtones out, they cannot affect the audible range.

Why do you think that a microphone cannot transduce intermodulations?  


Kal Rubinson

Music in the Round

Senior Contributing Editor, Stereophile

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56 minutes ago, Kal Rubinson said:

Why do you think that a microphone cannot transduce intermodulations?  

 

I suspect the answer involves the difference between radio frequencies and sound frequencies. However, I'll let the technical folk answer this one. In any case, it sounds like you are suggesting that ultrasonic sound is distortion.

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32 minutes ago, tmtomh said:

So if a recording has ultrasonic frequencies in it - even ones generated by the original instruments - then wouldn't those frequencies increase the likelihood of intermodulation distortion in the audible range?

Hi,

This would not occur. If you examine an intermodulation test, then the two frequencies, assumed to be 18kHz and 19kHz are at power levels such that the power amplifier setting is 1watts, 10watts, or 100watts. A reasonable amplifier will have intermodulation at approximately -70dB for 100watts in 8ohms, and much lower for the lower powers.

 

The ultrasonic energy in recordings is at -40dB for 10kHz and above, reducing to -60dB for 20kHz. This means the power in the 10kHz to 20kHz range will not produce intermodulation that is measurable. See the following :

 

https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements

 

For 50watts into 8ohms, the 1kHz intermodulation product is at -76dB. If the power in the 10kHz to 20kHz is at most -40dB, then this translates to 5mW power at 10kHz, and 50uW at 20kHz. In the ultrasonics it is even lower. Even if we assume it is -76dB intermods for such low powers, this then translates to -99dBW, which is 125pico-watts of intermodulation power. Again, it will be even lower for ultrasonics - the lower power generates even lower intermodulation products, such that they cannot be measured. Of course, this assume a class A/B amplifier....... class D has its own issues.

 

So, we do not need high resolution, and certainly do not need MQA to provide a lossy, aliasing sound, for which we can't hear the ultrasonics.

 

Regards,

Shadders.

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1 hour ago, Kal Rubinson said:

Because the interaction that results in changes in the audible range has already occurred in the performance and can be captured without ultrasonic frequency response in the reproduction chain

 

1 hour ago, lucretius said:

 

Overtones are overtones. If you cut the ultrasonic overtones out, they cannot affect the audible range.

Kal is correct. The overtones don't exist by themselves in a vacuum. 
BTW, are you aware that many microphones - especially many of the most well regarded vintage ones - can't capture ultrasonics, or even anything approaching 20khz? Or that tape machines in studios were often purposely setup not to be able to record anything over 15khz or so? Yet many who listen to 96k or192k digital transcriptions of these tapes would make the same claim as you - that its the (non-existant) ultrasonics in their hi-res files that is responsible for their good sound. 


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20 minutes ago, firedog said:

 

Kal is correct. The overtones don't exist by themselves in a vacuum. 
BTW, are you aware that many microphones - especially many of the most well regarded vintage ones - can't capture ultrasonics, or even anything approaching 20khz? Or that tape machines in studios were often purposely setup not to be able to record anything over 15khz or so? Yet many who listen to 96k or192k digital transcriptions of these tapes would make the same claim as you - that its the (non-existant) ultrasonics in their hi-res files that is responsible for their good sound. 

 

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:

 

Kind_of_Blue_-_HDTracks_96kHz.thumb.png.742e571e6627190d5ff31974ceb0fd10.png

 

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.


Archimago's Musings... A "more objective" audiophile blog.

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5 minutes ago, Archimago said:

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.

Hi,

Yes - but the main content from 100Hz is at -35dB, so this is a difference of 60dB, as per the many download recordings analysed by Hifi News. Maybe they have not used all the bits - 8bits at the top going spare ?

 

Regards,

Shadders.

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14 minutes ago, Shadders said:

Hi,

Yes - but the main content from 100Hz is at -35dB, so this is a difference of 60dB, as per the many download recordings analysed by Hifi News. Maybe they have not used all the bits - 8bits at the top going spare ?

 

Regards,

Shadders.

 

Indeed. I'm certainly not going to argue that KoB "needs" more than 16-bits either!

 


Archimago's Musings... A "more objective" audiophile blog.

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1 hour ago, firedog said:

BTW, are you aware that many microphones - especially many of the most well regarded vintage ones - can't capture ultrasonics, or even anything approaching 20khz? Or that tape machines in studios were often purposely setup not to be able to record anything over 15khz or so? Yet many who listen to 96k or192k digital transcriptions of these tapes would make the same claim as you - that its the (non-existant) ultrasonics in their hi-res files that is responsible for their good sound. 

 

Huh?  I am making the claim that the sample rates larger than 48kHz are unneeded (doesn't improve the audible range -- and especially when there are no or limited ultrasonic sounds in the higher frequencies) and many cases, unwanted (there exists ultrasonic sound in the higher frequencies but it is nothing but a source of distortion).

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2 hours ago, Paul R said:

So guys - you can argue this back and forth until the cows come home. Logic should be:

 

1. Do hi-res recordings sound different?

    No. ->. Stop

 

2. (Yes) Do they sound different because they are different masters?

    Yes -> choose the one you like best. Stop. 

 

3. (No) Does the high res recording sound better? 

     No -> Stop

 

4. (Yes) Why does the high res recording sound different and better? 

    Go for it with the 14 mainstream theories of why, or invent your own. 

 

Personally, I usually think that 24/96 or above sounds a bit better than red book. The why I usually wind up at is the filters make a difference.  I do not care what the filters are particularly, I just want the sound that pleases me the most. After all, I am the one listening to it. 

What 'sounds' better can be very different from something that IS objectively better.  Simply because frequencies above about 20kHz cannot be heard directly doesn't mean that the IMD or other effects along with circuitry/software don't make a difference.

 

Sometimes, there is the subjective sense that 96k/24 sounds better than 48k/24, and I cannot (will not) argue either way about that.

 

John

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Well, does it really matter? Resource limitations have essentially become non-issues. Go with the higher sample rate to be on the safe side.  😎


Anyone who considers protocol unimportant has never dealt with a cat DAC.

Robert A. Heinlein

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26 minutes ago, Paul R said:

Well, does it really matter? Resource limitations have essentially become non-issues. Go with the higher sample rate to be on the safe side.  😎

I agree that it is okay to use higher sample rates, but wider bandwidth and higher sample rates aren't needed or actually beneficial for listening (linear applications.)  Also, higher bandwidth than needed/usable is a burden, not an asset.  (What I mean by 'burden' is that a lot of electronics, and even some software, can create more artifacts when presented with unneeded signal.)

It is my suspicion (and opinion  of others) that the 'difference' often claimed for wider bandwidth source material is actually additional or change in distortion more than anything else.

On the other hand, if I have to up/down convert over and over again -- I'd' rather keep the higher rate.  That doesn't mean that a nice rolloff well above the audible range is a bad thing (e.g. starting at a dB or so at 25kHz.)

When I rolloff for audible band, my stuff is essentially 0dB at 20kHz and a few dB at 21.5kHz.  It is nailed entirely at 23.5kHz.  When needing to support wide bandwidth (to make places like HDtracks happy -- they like to see lots of noise above 25kHz), my software doesn't always keep the audio and above-audio bands together, but separates them for processing -- it mitigates IMD to do the split before processing, then recombine.  (In fact, doing the split in the audible bands is also helpful.)

 

 

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if I had to bet, I'd bet on filter slopes

 

then there is the possibility that ultrasound can affect perception in the hearing range

 

 


"The overwhelming majority [of audiophiles] have very little knowledge, if any, about the most basic principles and operating characteristics of audio equipment. They often base their purchasing decisions on hearsay, and the preaching of media sages. Unfortunately, because of commercial considerations, much information is rooted in increasing revenue, not in assisting the audiophile. It seems as if the only requirements for becoming an "authority" in the world of audio is a keyboard."

-- Bruce Rozenblit of Transcendent Sound

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2 hours ago, Kal Rubinson said:

Nope.  I intentionally did not use that word.  Intermodulation is the result of interaction of two signals.  If the interaction is inherent, useful or appreciated, as in the case of interaction between the ultrasonic and in-band output from a musical instrument, it is not distortion.  OTOH, if it is introduced by an external device and represents something that was not present in the original performance, the same phenomenon would be described as intermodulation distortion.   It's like the home definition of a weed.  If you need/want/like it, it's just a plant.

 

Isn't what you described as intermodulation also called intermodulation distortion (IMD)?  See https://en.wikipedia.org/wiki/Intermodulation.  In which case, it is distortion -- whether you prefer it or not is up to you.

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5 hours ago, lucretius said:

 

Huh?  I am making the claim that the sample rates larger than 48kHz are unneeded (doesn't improve the audible range -- and especially when there are no or limited ultrasonic sounds in the higher frequencies) and many cases, unwanted (there exists ultrasonic sound in the higher frequencies but it is nothing but a source of distortion).

 

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.


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3 hours ago, John Dyson said:

You are pointing to a manufacturer's spec sheet.  They always always give ideal distortion characteristics.  What was the source/load impedance while measuring the distortion?   If they specify the soruce/load impedances, they are usually not in the more challenging ranges.

 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


"If you can't hear the difference between an original CD and a copy of your CD,

you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

PROFILE UPDATED 18-06-2019

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7 hours ago, Shadders said:

So, we do not need high resolution, and certainly do not need MQA to provide a lossy, aliasing sound, for which we can't hear the ultrasonics.

 Richard

 Try telling that to highly respected Recording Engineers such as Barry Diament and Cookie Marenco , or the large percentage of A.S. members, especially Miska, who love their High Res and especially DSD. IIRC, one of Miska's favourite amplifiers had a 1MHZ bandwidth too.

Many of Barry's recordings contain genuine musical content to past 55kHZ. If you are unable to hear the differences via a competent system between the RBCD version and the 24/96 or 24/192  version, or the same with high quality DSD recordings I feel sorry for you, as your hearing capabilities must be even worse that this 80 year old's hearing. :P

Having said that, there is something about the SACD HF noise residuals that annoys me a little.

 

Alex


"If you can't hear the difference between an original CD and a copy of your CD,

you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

PROFILE UPDATED 18-06-2019

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2 minutes ago, sandyk said:

 Richard

 Try telling that to highly respected Recording Engineers such as Barry Diament and Cookie Marenco , or the large percentage of A.S. members, especially Miska, who love their High Res and especially DSD. IIRC, one of Miska's favourite amplifiers had a 1MHZ bandwidth too.

Many of Barry's recordings contain genuine musical content to past 55kHZ. If you are unable to hear the differences via a competent system between the RBCD version and the 24/96 or 24/192  version, or the same with high quality DSD recordings I feel sorry for you, as your hearing capabilities must be even worse that this 80 year old's hearing. :P

Having said that, there is something about the SACD HF noise residuals that annoys me a little.

 

Alex

Hi Alex,

I was intending this response to illustrate that the power levels at 20kHz+ is so low, that intermodulation products are therefore extremely low, so as to be below the noise floor and inaudible.

 

I agree that higher bit depth is beneficial, at 48kHz, but 96kHz+ is not required for audible information - as the ear cannot hear it.

 

The anecdotal evidence here is that no one has ever complained about class D amplifiers - which have vastly greater significant noise at 20kHz+, compared to class A/B. Maybe the experience is that the difference between 16bit and 24bit is the difference heard ?, not the frequency extension.

 

The fact that no hifi press has complained about class D high frequency issues, just shows you that it cannot be heard - so, the effect of MQA is purely the inband changes of its processing, not whether it is lossy high resolution.

 

Regards,

Richard.

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