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