From: carver@cs.umass.edu
Newsgroups: rec.audio
Subject: Re: Black rubber CD rings - Any good ?
Date: 15 Oct 92 19:20:22 GMT
Reply-To: carver@cs.umass.edu
Organization: Computer and Information Science, University of Massachusetts, Amherst, MA

jj@alice.att.com (jj, curmudgeon and all-around grouch) writes:
>In article <Bw3D01.Kt5@watserv1.uwaterloo.ca> bmaraldo@watserv1.uwaterloo.ca (Commander Brett Maraldo) writes:
>>	From my experience the rings do not add enough weight to the disc to
>>cause tracking or speed feedback problems.
>Well, we've had opposite experiences, because, as I've previously
>stated, I found (without looking for it) at least one combination
>of readily available products that caused speed control problems
>in a big way.
>
>In fact, these control problems, including "silence" as a result,
>were the ONLY audible effects the rings had in this particular
>examination of such.


I have tried a number of different "dampers" on inexpensive Philips
transports and have never had any speed servo problems.  This includes
the truly "massive" Simply Physics damper...so I think that problems are
unlikely.  Furthermore, the Simply Physics damper improved the tracking
of the player (as determined using the P-Vernay CD)...despite my
misgivings about its mass (and sound---see below).

Note that the stretchy Navcom rings weigh almost nothing and so won't
have such problems (they can have other problems, though, since they
make the CD just slightly wider and thicker at the edges).

Do dampers or rings change the sound?  I believe that they do, at least
sometimes.  Do they improve the sound?  I have never found the changes
from dampers to be improvements.  This, despite the fact that one damper
came with my Prism player and the Simply Physics was used later by the
same manufacturer, who thought they made significant improvements...as
did AHC in TAS.  I always found that they resulted in "decreased energy"
in the music:  less bass power, too smooth highs.  (Note:  if you
don't/can't/won't hear differences between wires then you won't hear
these differences either.)

Another problem that I had with dampers was getting them to work right.
The Simply Physics often didn't end up being perfectly centered and would
cause the transport to vibrate...no surprise that this wouldn't be good
sounding.  Likewise for the other dampers due to the design of the
Philips clamping system...puck rides against a plastic bearing surface
which gets an indentation over time...adding a damper raises the height
of the CD and causes the puck to ride differently...again causing vibration.
If you try dampers, you should definitely take the cover off your player
and see/feel how they are operating.

As for the Navcom rings (CD "rubbers"), with a few CDs I found they they
improved the sound...very slightly...with others there was no difference.
Never any "degradation."  However, they are expensive and very tricky to
get onto the CDs...especially without bending the CDs, which I have
heard suggested as maybe causing tiny cracks in the polycarbonate.

Bottom line:  I don't use any dampers or rings and wouldn't recommend them,
though I am fairly convinced (I have not wasted MY time PROVING it!)
that they can CHANGE the sound of at least some CDs and players.


Norman Carver
Computer Science Dept.
University of Massachusetts
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