Newsgroups: rec.audio

>
>I bet that if the same test were done, but with standard CD technology A/D 
>and D/A vs. straight wire, one would get the same null result.
>
>And yet, how do CD players sound different if digital sounds like nothing?
>
>I find it very plausible that some of the CD players one buys off the shelf
>are measurably "out of spec" compared to the prototype A-D/digital
>processing/D-A hardware that the engineers rigged up for a scientific test.
>Perhaps quality control is poor enough that different units of the same model
>can have widely varying performance.
----------
Jeeze...Again....
It is mostly in the analog(ue) parts of a CD player where differences in
sound are created.  There has been some discussion and papers showing how
jitter causes some audible differences as well.  A lot of the difference used
to be in how the filter was implemented.  Now that oversampling is here (8x),
the power supply design becomes very important as well as shielding of the
analog sections and rfi/emi design.  Cheap workmanship can have a major
impact on shielding and rfi/emi deisgns causing a passable unit to go "bad"
with a few bumps or after some time at temp and humidity.

Our R&D manager went to Japan many times since '84 to sell their "high-end"
makers of CD our optocouplers to carry the digital information from the
noisy digital powersupply section to the "quiet" analog section.  He and I
went to a very high end store back in ~'85 to listen to the players with
these good design features and all the $800 to $1500 single CD players
sounded slightly different.  Their literature and the salesman said that the
reason to buy brand A over brand B was due to different filter implementations.
Good filters were hard to design (read this as expensive components) and there
was some debate on what phase characteristics sounded "best"(tm).  With over-
sampling, this isn't as much an issue as the reason for oversampling is it
allows CD player makers to build players that have good aliasing filters that
don't produce alot of phase distortion at a reasonable price.

Back in '85 when I listened to these "high-end" CD players, I couldn't say
which I preferred, but today I own the "top of the line at the time"  SONY cunsumer CD player as it
sounds just as good to my ears (they have been called Golden by some).  Of
course it has 7-way power supply design which makes for a very clean signal
unlike the $100-$300 units I've listened to and gotten for my parents who
don't care.  I can't justify spending over $400 for a CD player from what
I've heard when there are thing like amps and Velodynes out there
to buy as well as putting CD into my van.

BTW, I just put a Sony CDX-5080 in my van with MB Quart Qm318CX speakers
in the front and Boston Accoustic 767 6x9 speakers in the rear all
running off a Rockford 460sd (4x30Watt/4Ohm) amp and it sounds fantastic.
Why should I buy $400 speaker wire when I can use the money to put good
sound in my autos?  In short, we all have different ideas of where we
should spend our money for better sound.  I've chosen to have Very Good
sound in more places than slightly better, if at all better, sound at home.

Kirk (playing a CD in my van is FAR better than making a tape of a record
off the best turntable/arm combination and listening on a tape player) out




Newsgroups: rec.audio