Please explain this criticism of CD audio

[Dave C]

I just use a CD player with a switchmode supply, then balance the volume to mix with the mechanical high frequencies emmited from the power supply. It really fills in the missing ultrasonic component.

You owe yourself this tweak. The soundstage is startling.

What?? explain please.

 

[Dave C]

I've concluded that one would have to spend about 10 grand for a turntable to properly spin a record without all the groove noise, flutter and wow that the needle picks up. I'd rather spend $500.00 on a better than most CD player and not have the groove noise, flutter and wow of the turntable and record. I see that as the tradeoff here. Plus I can jump or program any play order I want.

 

[JBL GUY]

All I'm saying is that a recording should capture the affect that ultra high frequencies have on lower frequencies, because they will already be affecting the sound that is being recorded, in the audible regions, and that affected sound will be what is recorded.

But I'm way out of my element on this stuff. That criticism of CD audio just doesn't, from my un-educated opinion, seem to make much sense. But I'd love to hear why I'm understanding it wrong, which I very well could be.

Yes to the same extent that all the frequencies reaching the microphone do.

But what about the affect of the ultrasonic frequencies on themselves.

If 2 ultrasonic frequencies with a frequency difference of 3000 Hz encounter a non-linearity, then the sum and the difference of the 2 ultrasonic frequencies will be generated.

And of course one of the resultant frequencies will be 3000 Hz.

Well with in the generally accepted hearing range.

So far we are still on the out side of the ear canal.

 

[RobRoy]

Actually a "beat frequency" is from the mixing of two or more frequencies, it does not come from a single frequency. And in your not to correct example, the 200kHz signal would have to have been reproduced to mix with another signal to have the result, in your example 12Khz.

You are absolutely right. I basically said that 5=2+
My bad.

 

[RobRoy]

All I'm saying is that a recording should capture the affect that ultra high frequencies have on lower frequencies, because they will already be affecting the sound that is being recorded, in the audible regions, and that affected sound will be what is recorded.

But I'm way out of my element on this stuff. That criticism of CD audio just doesn't, from my un-educated opinion, seem to make much sense. But I'd love to hear why I'm understanding it wrong, which I very well could be.

I firmly agree. Problem is, I remember arguing tube vs solid state in the mid-70's from a price vs performance point of view and got nowhere. Now, the same is happening with vinyl vs CD. And here is the problem: It is really like a religious/political discussion, which is off limits here.

I say that as someone that loves my vinyl collection, but if I want the best possible sound, it ain't vinyl. I like it for different reasons, though sound is very good.

 

[JBL GUY]

Originally Posted by JohnVF View Post

All I'm saying is that a recording should capture the affect that ultra high frequencies have on lower frequencies, because they will already be affecting the sound that is being recorded, in the audible regions, and that affected sound will be what is recorded.

But I'm way out of my element on this stuff. That criticism of CD audio just doesn't, from my un-educated opinion, seem to make much sense. But I'd love to hear why I'm understanding it wrong, which I very well could be.

RobRoy
I firmly agree. Problem is, I remember arguing tube vs solid state in the mid-70's from a price vs performance point of view and got nowhere. Now, the same is happening with vinyl vs CD. And here is the problem: It is really like a religious/political discussion, which is off limits here.

I say that as someone that loves my vinyl collection, but if I want the best possible sound, it ain't vinyl. I like it for different reasons, though sound is very good.

Yes to the same extent that all the frequencies reaching the microphone do.

If one is talking about how sound is recorded, one has to ask, does the microphone behave in the same way as the HRTF does when one listens to live music.

Of course one still has the HRTF when listening to reproduced music, but if part of the information is left behind in the recording or reproduction process then all bets are off.

And what about the affect of the ultrasonic frequencies on themselves.

If 2 ultrasonic frequencies with a frequency difference of 3000 Hz encounter a non-linear device, then the sum and the difference of the 2 ultrasonic frequencies will be generated.

And of course one of the resultant frequencies will be 3000 Hz.

Well within the generally accepted hearing range. Of course this will not happen if the ultrasonic frequencies are not recorded and reproduced.

So far we are still on the outside of the ear canal.

I have and use both CDs and records, and I enjoy both formats. But as of yet, we are not able to reproduce music that is completely indistinguishable from a live performance.

To say that a CD is able to contain all of the sonic information (vector vs scalar information, very small timing differences on the order of single digit microseconds, ultrasonic content and so on) that is available at a live performance is a bit of a stretch, and gives no motivation or encouragement for the improvement of music reproduction.

 

[flavio81]

The author is displaying his ignorance of how digital audio works and/or his prejudice in favor of the more easily understood analog system. The sampling theorem teaches that a band-limited signal may be sampled, digitally encoded, and reconstructed without loss from the digital code as long as the sampling frequency is at least twice the highest frequency in the original signal. The word length used for each sample determines the signal-to-noise ratio. The CD system's 16-bit linear encoding puts the quantization noise 96 dB below the maximum signal level, which is more than 20 dB better than the performance of a first-rate phono system. Applying dither during production slightly reduces the signal-to-noise ratio, but it improves the sound by decorrelating the noise from the signal. Post-dither, the noise floor sounds like the white noise that you'd get from an extremely quiet analog tape deck. The CD system's sampling frequency of 44.1 kHz provides frequency response to just below 22.05 kHz, which exceeds the generally accepted upper limit of the human auditory system.

If you're up for some advanced math, Wikipedia's article on the sampling theorem provides a good background. Here's the link: http://en.wikipedia.org/wiki/Sampling_theorem.

Basically the thread could be ended here. Nothing more to say, really.

The papers who claim that humans can 'hear' about 20KHz are nonconclusive, and plus, if we can 'hear' them, that doesn't mean they're essential to realism.

Finally, after 1979 some records started to be cut using a digital mastering delay; this means that the audio in them was passed through a machine like this one:

... before reaching the record. This particular machine has a more or less unsophisticated ADC/DAC chain that contains the often maligned brick-wall filters, as i've analyzed here:

http://www.vinylengine.com/phpBB2/viewtopic.php?p=288385#288385

You can bet more and more records were cut using a digital delay through the 80s. Records praised by audiophools as "warm analog sound".
Enjoy your digital audio, folks. And this comes from a vinyl fanatic.

 

[JonVH]

All these white papers on the web and in books are so inconclusive and misleading. It's no wonder we get so confused and what we read doesn't agree with the real world. The answers to life clearly don't reside here or on the wikipedia fallacy.

 

[RobRoy]

All these white papers on the web and in books are so inconclusive and misleading. It's no wonder we get so confused and what we read doesn't agree with the real world. The answers to life clearly don't reside here or on the wikipedia fallacy.

That's why DBT is my "roseta stone".