[Sonnova]

On Thu, 10 Sep 2009 08:27:41 -0700, ST wrote
(in article ):

On Sep 10, 12:14*pm, Steven Sullivan wrote:
Dick Pierce wrote:
Steven Sullivan wrote:
Is it possible CD format technology already matured long time ago and
there's nothing new can really improve the sound?

How long is 'long ago'? Oversampling can prevent some possible sonic
* artifacts. Oversampling DACs didn't become common in consumer units
* until the early 90s.
Not so. The Philips CD players did oversampling in the 80's,
IN 1987, it was common enough to inspire a NYT article where
at least 3 explicit examples of products from Magnovox, Denon
and Accuphase were featured as having oversampling. Display
adds for a Mitsubishi CD player appeared in the Chicago Tribune
in November of 1986.
A brief search reveals that oversampling was QUITE common before
the end of the 1980's

OK, late 80s rather than early 90s.

And, as I pointed out elsewhere, conversion techniques like
ovsersampling are not related to the redbook format. That has
not changed since the early 1980's

Since the Redbook format obviously has not changed, I assumed he must have
been referring to the playback technology.

--
-S
We have it in our power to begin the world over again - Thomas Paine

Yes, playback technology. Or did DAC really make significant
improvement in the past 15 years. The prices may have gone down and
some boutique DAC gone several times up.


Just because Redbook hasn't changed (that's just format specs anyway) doesn't
mean that there haven't been improvements in the equipment chain BEFORE the
actual CD is mastered to glass. Part of the CD mastering chain, for a number
of years, was the Sony PCM-1610, 1620 and 1630 digital recorders. All analog
and most digital recordings bound for the CD mastering room in the early days
was put on video cassette (half-inch U-Matic was the standard) via one of
these Sonys. They were lousy and I should know, I owned and used a Sony
PCM-1620 for years*. Filled with 741 style op-amps and electrolytic and
tantalum capacitors in the signal path, CDs made with them in the chain
sounded truly dismal. I'm sure that at least part of CDs early bad reputation
for general harshness and distorted highs was a direct result of the
industry-wide use of these junkers. Eventually, as computers came along and
people started to pay closer attention to the production side of things,
these machines were retired in favor of other means to make and deliver
digital recordings to the mastering lab.

On the other end of the chain, the quality of most players has improved too.
CD players no longer have steep analog filters full of cheap op-amps and
electrolytic capacitors cascaded into multi-pole filters for antialiasing.
Most antialiasing is done today in the digital realm and oversampling has
placed the need for this kind of filtering far above the audio passband.
Today's CD readers are less error prone than were their forebearers and less
likely to cause as many interpolation-level errors where the Solomon-Reed
error correction ends up having to "guess" at what the digital word is
supposed to be. Even though it's an intelligent guess and probably, in and of
itself, is not sonically catastrophic, add all these things together and the
result is that with todays digital filters, Delta-Sigma DACs, and more robust
front ends, digital playback has improved considerably over the early
machines.

*I used a PCM-1620 with a Sony SL-HF1000 Super Betamax (which, unlike VHS
recorders of the period, allowed one to turn-off all video enhancement
circuitry in the recorder. This was done specifically to facilitate digital
audio recording) to record a local municipal symphony orchestra for a number
of years. For backup, I ran a Sony TC-880P reel-to-reel recorder at 15
i.p.s., half-track using Sony's FeCr mastering tape (for which the 880 could
be optimized. Most recorders couldn't supply enough bias current to use this
tape). I have always thought that the analog back-up recordings sounded MUCH
better than the digital masters - tape hiss and all. When I finally decided
to transfer the entire library to DAT in the 1990s, it was the analog
reel-to-reel tapes that I used for the transfers, not the digital recordings
made on the Betamax recorder and the PCM-1620 because they sounded so poor by
comparison (even when the transfer was done digital-to-digital).