John Curl's Blowtorch preamplifier part II

[jneutron]

Originally Posted by SY

Frequency and time are conjugate variables. Pick one.

No. I refuse to pick just one...

Time, as in group delay...

Happy New Year SY..

John

[jneutron]

Originally Posted by Esperado

My disco is full of *wonderful* recordings.

Your disco?

jn

[PMA]

Originally Posted by john curl

What, you don't especially like mp3? I heard that it was almost undetectable in many double blind tests. Where was I misinformed?

Problem with unexperienced listeners, most probably. With experienced listeners, we have very high score in dbx tests mp3 (256kbps and more) vs. original. Depends. One may organize the test to get null results, if he wish so. Just use bad acoustics, poor audio equipment, bad recordings and unexperienced listeners and your are at the null result suddenly.

[bcarso]

Originally Posted by PMA

Problem with unexperienced listeners, most probably. With experienced listeners, we have very high score in dbx tests mp3 (256kbps and more) vs. original. Depends. One may organize the test to get null results, if he wish so. Just use bad acoustics, poor audio equipment, bad recordings and unexperienced listeners and your are at the null result suddenly.

Of course the famous story is when Philips developed one of their compression algorithms and had panels evaluate material to see if they could detect artifacts. The panels didn't notice anything. Then the late Bart Locanthi gave it a try, and came back with a list of problems ("listen here at 4:33 and hear the background tone at 1.3kHz...." and similar).

When thus coached most listeners had no difficulty in hearing the problems. But suits at Philips already had decided in favor of the schemes. So it goes. Philips, I might add, are notorious for being bullies, packing standards committees with their loyal and faithful, and ramming through what they desire. My first patent attorney used to say "Philips is truly evil. And I mean that in the nicest possible way."

[Esperado]

Originally Posted by jneutron

Your disco?

Record's library (my poor English :-(

[john curl]

Yes, PMA, I agree with you, but what does everyone else think?

[Esperado]

Originally Posted by john curl

You better tell 'jj' that he is the 'audio industry' and not an 'audio engineer'. If he agrees with you, I will go along with it.

Is AT&T Bell Laboratories a recording studio or a record production company ?
Did i make a misunderstanding between "audio" and "sound" engineers in this context ?

Yes i disagree with MP3 for any professional use and, as a consultant, i had made a big change in the projects of a big radio station which wanted to sample all their records in a compressed format. Explaining them that, for the human price of the copy process, it would be better to copy in uncompressed format (CD at this time), expecting the prices of bytes on HD drive to decrease rapidly with time.

[Kindhornman]

Saying that the original MP3 recordings were perfect is like saying that Bose is high end audio! The premise that if we can remove unneeded information it will not be missed is Dr. Bose great gift to audio reproduction. I'm with Jneutron, Eperado, and others that say that we need to look at the 3D aspects of the original waveforms and reproduction. How is it that we hear the differences between sounds. It is not the steady state, it is the initial waveforms rise time, or leading edges that gives us those clues.

Jan,
You seem very up on the way that we actually process sounds between the ear and brain. Someone said to me the other day that we only hear the positive wavefront and not the negative. Perhaps I am not using the correct terminology here, what I think he was saying is that we only hear a pressure wave and not the opposite, a negative pressure? What is your take on that, I am in the dark on that principal.

Happy New Year and a safe night to all.

[john curl]

Thank goodness, you made the right decision, Esperado. The local rock station here, did just the opposite, and I can't even stand listening to it in the car.

[SY]

Originally Posted by john curl

What, you don't especially like mp3? I heard that it was almost undetectable in many double blind tests. Where was I misinformed?

Can you cite a reference for that? MP3 is excellent for its intended purpose, but I've never seen any data claiming it was indistinguishable from uncompressed. In dbts, I was able to distinguish it and rank by degree of compression, and I've never claimed to be a golden ear.