Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site decwrl.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxj!ihnp4!zehntel!dual!decwrl!dec-rhea!dec-bergil!lauck From: lauck@bergil.DEC Newsgroups: net.audio Subject: re: West of Oz CD Message-ID: <3872@decwrl.UUCP> Date: Mon, 8-Oct-84 20:37:21 EDT Article-I.D.: decwrl.3872 Posted: Mon Oct 8 20:37:21 1984 Date-Received: Wed, 10-Oct-84 04:06:42 EDT Sender: daemon@decwrl.UUCP Organization: DEC Engineering Network Lines: 101 <> >(1) First note that the LP is a direct-to-disc recording, so there was >no analog master tape to degrade the sound. In the September AUDIO, >Bert Whyte (himself the recording engineer on some direct-to-disc >sessions) performed the same comparison, both for this recording, >and for the previous McBroom recording ("Growing up in Hollywood Town"). >The "West" CD was made from a digital mastertape (recorded from the >same feed that made the direct-to-disc master), whereas the "Growing up" >Whyte thought the "Growing up" >CD was deficient compared to the LP, whereas the "West" CD was >indistinguishable. He was listening to the LP using high-end equipment. I'm really surprised that Bert Whyte had difficulty distinguishing the LP from the CD. The difference is so great that there is no need to do double blind testing. You hear the difference and KNOW it's there. In fact, I was shocked at the extent of the difference. I'll have to get a copy of the September Audio and read the article. I'm curious as to the record playing equipment involved. I didn't bother to buy the CD of "Growing up", since it would prove nothing except the limitations of analog tape recorders, probably not the state of the art recorders at that. I certainly didn't feel the need to buy the CD lest the analog disk wear out.... >(2) I wonder if Tony took care in matching volumes when doing his test. >This is especially difficult when the test is performed, as he says, >by first listening to the CD all the way through and then putting on >the LP. I took no care in matching the levels, I just played the music. The tonal balance was so different that the concept of level matching makes no sense. At what frequency do you match levels? If measuring power, on which portions of the program material? After the inital test I then played various cuts, one cut at a time, and listened at all combinations of CD or LP louder, or as close as possible by ear. In each case, the LP sounded better, even when it was much too soft or much too loud for my taste and the CD was set "properly". I then called up my pro digital friend, E. Brad Meyer, who is an audio writer and recordist. I told him that he was going to have to "reconvert me" back into the pro-digital fold. He suggested that perhaps Sheffield should have made their CDs by playing a pressing of one of their direct disk records into a digital recorder. I thought he was joking. Little did I know... The prescribed treatment was to borrow a SONY PCM 710 and an ABX double blind comparator box. I had to swear to level match within .1db. I assured him that I had a tone generator and a suitable meter. My initial tests consisted of just listening through the PCM and comparing it to the Sheffield recordings and other audiophile recordings, including the Performance Recordings Prokofiev 6th sonata and the Reference Recording Symphonie Fantastic. It was immediately clear that any PCM degradation was minimal, subjectively at least an order of magnitude less than the difference between the "West of OZ" CD and LP. There was no question that the LP and the LP via the PCM both sounded vastly better than the CD. Perhaps my friend Brad had been serious in his recutting suggestion. I then level matched the PCM to within .05 db on each stereo channel. To those who haven't done it before, it is a real pain, unless you have ten turn pots and fancy meters. It took me two hours, and caused me nearly as much pain as when I measured the mass of an electron in college physics. (My degree was in mathematics.) The resulting level setting put the PCM in a poor position, since without an attenuator on the output I couldn't get a level match with a recording level above -24db. This meant I was running effectively at 13 bits. When the stylus was lifted, the PCM noise (dither) was clearly audible, making identification of the PCM immediate. However, this noise was not detectable when a record was playing since it was far enough below the record noise of all the records I played. The final result: I correctly identified the PCM in 24 out of 42 trials, which is not statistically significant. Subjectively, I felt that any differences were at the very limit of my perception. Perhaps I could keep up this performance every night for several months and reach statistic significance, but why? It became clear to me that the problem with bad sounding CDs is not in the system itself, since the CDs sound much worse than the LPs via PCM. (The 710 uses the same encoding format as CD's.) The obvious explaination, one argued publically by many, is that recording engineers and record producers haven't learned to use the new, more accurate digital medium. I don't buy this. The technology has been available for five years. By now these problems should have been overcome. What's going on here? I hooked the PCM710 up to my video recorder and made some live recordings of my wife's Steinway piano and my son's 12 string guitar, using a pair of AGC C451 cardiod condenser microphones. The result: the piano sounded much like CD piano recordings, not too bad. The guitar suffered from moderately severe "digitalis". Do I need new microphones? Here's a subject to ponder: why do digitally mastered LPs sound bad when digitally copied analog LPs sound good? Why should analog then digital sound good while digital then analog sound bad? Is it a system interaction problem? Is it a psychoacoustic problem? Tony Lauck ...decvax!decwrl!rhea!bergil!lauck