Another great post.
But could you explain how did you prove that "No human can hear ... " and what you mean exactly by a "properly produced digital PCM recording"? CD, 24bit 192 kHz? Apologies if you explained it in another topic and I missed it. But stated exactly as written without justification it seems to distort the line you were so well presenting.
Disclaimer 2 - I am a subscriber of the Tape Project
Disclaimer 3 - I read all TELDC and even built a small panel in the 90's! Great fun.
To answer this, let me tell you a story about the best recording of Respighi's "Pines of Rome" that I have ever heard. It was recorded in 1959 by Fritz Reiner and the Chicago Symphony by RCA "Red Seal."
The LP had superb dynamics, essentially full frequency range (30 Hz to 15 KHz), great "hall sound", and a high degree of realism. It was pure joy and very exciting to listen to, despite all the obvious faults that were epidemic in LPs of that era (surface noise, distortion, wow and flutter, poor S/N, and general instability).
When CD's became available years later, I couldn't wait for RCA to re-release that recording on CD so that I could eliminate all the faults heard on the LP. RCA finally did so in the late 80's and I couldn't wait to bring the CD home and play it.
Boy, was I disappointed. The CD had essentially no dynamic range, no bass, many of the instruments could barely be heard, and it in general sounded like I was listening through a telephone!
I was furious. I knew that digital recordings could (and should) be superb, since I was making them myself and knew this to be true. So I was determined to find out what was going on at RCA to ruin this recording.
After enduring considerable hassles finding my way through the telephone maze at RCA, I finally got to those responsible for releasing the recording. After hearing my complaint, they explained what had happened this way:
The original master tape recording was NOT made in 2-channel stereo. It was made using a 16 track recorder and multiple microphones -- in stereo -- on each orchestral section (violins had 2 mics, trumpets had 2 mics, etc.) They also placed mics out in the concert hall to record the sound of the hall sound.
They then mixed down the 16 track tape to get a 2-channel stereo recording that could be pressed to produce LPs. The recording engineer who did this work obviously really knew his stuff and did a great job of getting the right balance between the various orchestra sections, blending in the hall sound, and maintaining nearly full dynamic range and frequency response (particularly in the bass).
Although this was a mixdown, he kept it reasonably simple, and did not use compression, equalization, or artificial reverb. The performance was superb and his mix showed it off extremely well.
Twenty five years later, when RCA wanted to re-release the performance on CD, they did not have the mixdown used for the LP. So they had a different engineer do another mix of the original 16 channel tape for the CD. He totally butchered the job.
No matter how good the recording medium, if you put garbage in, you get garbage out. So the awful sound on the CD version of this recording was due to an horrible mix done by an incompetent sound engineer who had probably never been to a live, symphony orchestra concert.
Are the "still some people though" annedotal as well?Roger, your explanations are wonderful. They paint a very nice end-to-end picture of the topic at hand. So I hope you take this as a small criticism . Your explanation at the extreme are somewhat inaccurate. For example, when we state a number for compressed audio, it is the data rate, not the sampling rate. The sampling rate of MP3 is 44.1 Khz at data rates >= 128Kbps and doesn't change. The number mentioned is the number of bits per second of audio. Uncompressed audio is 1.4 Mbit/sec. 128 Kbps, is 11 times lower data rate while maintaining the same sampling rate. Note that I said sampling rate, not frequency response. Standard MP3 codecs roll off the high frequencies above 16 Khz at all but the highest data rates in order to keep distortion under control so looking at the sampling rate alone can be misleading. Here is a quick test someone ran:http://www.lincomatic.com/mp3/mp3quality.html
CD:
192 Kbps MP3:
And even 320 Kbps:
MP3 was designed for backward compatibility with MPEG Layer 2 and to be implementable in really low-end hardware. As such, even putting aside the above filtering, it is not able to achieve transparency at any date rate -- your anecdotal observations not withstanding . To be sure, at 384 Kbps it can sound very good but it still sounds different to good number of audiophiles. AAC or WMA Pro on the other hand, can achieve extremely good quality at those rates perhaps fooling substantial majority of listeners. Still some people though, can tell the difference from uncompressed.
No. We performed extensive listening blind tests at Microsoft while my group was developing WMA and WMA Pro codecs and some people, including present company , could tell the difference. The fraction was generally small though (1% to 5%).Are the "still some people though" annedotal as well?
As a codec, MP3 is cast in concrete and cannot change. So in that sense, yes.Amir, have you been keeping up to date with advancements in MP3 encoding since you left MS?
Thanks-good info.No. We performed extensive listening blind tests at Microsoft while my group was developing WMA and WMA Pro codecs and some people, including present company , could tell the difference. The fraction was generally small though (1% to 5%).
Note that Roger did point out one key thing: content type matters. Some content can be nearly transparent even at 128kbps (with good codecs -- not MP3). Others sound different at much higher data rate. In general, anything with transients is very difficult to encode. Roger gave one example: piano. A more common example is guitar strings. Even things like vocals or audience clapping in live concerts can be very difficult to encode. Put another way, if you have flexibility with what content you use, you can make any case about compressed music .
All of this said, we were quite successful in fooling audiophiles. Many could be put in the bucket of general public in their inability to hear compression artifacts. Their ears simply doesn't know what to listen for. So in that sense Roger is right.
Roger:
I'm going to have to take exception to some of your statements about the Pines of Rome. I've collected, studied and been at RCA when they pulled out these original master tapes including the Pines of Rome from the tape vaults. I've also done interviews with the engineers who were there assisting Layton and Mohr for the recordings including Jack Pfeiffer, Anthony Salvatore and Max Wilcox.
I think your source is totally confused on the 16 track. It was 1959 and I don't think they had that capability. I think your source was confusing the number of mikes with the number of tracks. These recordings other than the very early experimental stereo recordings like Zarathustra, weren't what we'd call purist, minimal miked recordings. Most RCAs, as opposed to Mercury of its day, used 7-9 mikes for their recordings. (of course Mercury stuck by their 3 mike setup.) I saw the master tape of POR and it was a three track tape, believe me. There's no way they would have mixed from 16 to 3 track.
Then let's go to the actual story of the release of Reiners Pines of Rome, one of the most powerful pieces of music out there! (Maazel and Wilkinson don't do a bad job either on Decca.) There were many pressings of the Pines released. The only one that truly represents the tape was the 1S pressing. Yes, one can hear some tape saturation and distortion on peaks on this tape. But RCA pulled this LP quickly off the shelves as the public was complaining that their tts of the day couldn't track the record (that's opposed to Mercury and George Piros who were known for their ability to put a dynamic cut down on the lacquer). Their tonearms literally jumped out of the grooves. So RCA went back to the studio, obviously cut four more lacquers before they could get it right (that's evidenced by the missing 2-4S stampers) and released a 5S stamper. The 5S could play on the tts of the day but RCA had compressed the dynamic range of the recording considerably. RCA then went another 5 stampers releasing a 10S that was markedly inferior to even the 5S and if I remember correctly, cut at a much, much lower level (but I'd have to go back and compare them to confirm). So essentially every stamper after 10S was not even close to what was originally put down on the first 1S stamper. Now the Chesky for some reason was also compressed; I haven't heard the Classic Records reissue but I wasn't a fan of their masterings. (somewhere in storage have the records of how many pressings were cut from the original POR and few other RCA releases that Chesky did as well as a pic or two of their mike setup.)
And the RCA 0.5 series? HP was being kind when he said they were 1/2 of what they should be
Roger-Disgree or agrree you always present things in a common sense manner that translates into real world information the audiophile can act on. It appears you were discussing Stereo imaging-or left to right balance. Could you consider how we would go about measuring front to back imaging and the spatial relationships between musical istruments and voices? Often described as air around the instruments or voices.
gregadd
[FONT="]Hi Myles,[/FONT]
[FONT="]Thanks for the fascinating information. No doubt, your sources are more accurate than mine as I only had a telephone call with which to work. And understandably, the representative at RCA to whom I spoke was not totally familiar with all the technical details from tens of years earlier, particularly when nobody who was involved in the work was available.[/FONT]
[FONT="]However, whether the master tapes were 3 track or 16 track doesn't change the fact that a mixdown was required to produce a 2-channel, stereo recording. My source was certain that the mixdowns from the LP pressings were not used on the CD. Therefore, the truly awful sound on the CD continues to be explained by the poor judgment of the "engineer" doing the mixdown rather than any inherent flaws in the digital recording process.[/FONT]
[FONT="]Best,[/FONT]
[FONT="]-Roger[/FONT]
Roger, your explanations are wonderful. They paint a very nice end-to-end picture of the topic at hand. So I hope you take this as a small criticism . Your explanation at the extreme are somewhat inaccurate. For example, when we state a number for compressed audio, it is the data rate, not the sampling rate. The sampling rate of MP3 is 44.1 Khz at data rates >= 128Kbps and doesn't change. The number mentioned is the number of bits per second of audio. Uncompressed audio is 1.4 Mbit/sec. 128 Kbps, is 11 times lower data rate while maintaining the same sampling rate. Note that I said sampling rate, not frequency response. Standard MP3 codecs roll off the high frequencies above 16 Khz at all but the highest data rates in order to keep distortion under control so looking at the sampling rate alone can be misleading. Here is a quick test someone ran:http://www.lincomatic.com/mp3/mp3quality.html
CD:
192 Kbps MP3:
And even 320 Kbps:
MP3 was designed for backward compatibility with MPEG Layer 2 and to be implementable in really low-end hardware. As such, even putting aside the above filtering, it is not able to achieve transparency at any date rate -- your anecdotal observations not withstanding . To be sure, at 384 Kbps it can sound very good but it still sounds different to good number of audiophiles. AAC or WMA Pro on the other hand, can achieve extremely good quality at those rates perhaps fooling substantial majority of listeners. Still some people though, can tell the difference from uncompressed.
It would be great if you or others on the forum would take the time to provide more detailed technical information on MP3. It is a big topic about which very little is known by audiophiles. Since it appears to be the medium of the future, we should all learn all we can about it. Again, thanks for your input.
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