In article , Andy Evans
wrote:
Following on from previous posts where I found that various damping
materials affected the sound of my Pioneer CDP used as transport only (I
have an outboard DAC), I've found the same with the CD-Rom I'm now
using.

I have also recently added damping material into my Meridian 200 transport
and feel this improves the results. However this seems to be due to a
reduction in the low level mechanical 'buzz' that was previously *just*
audible now being utterly inaudible. Doubt it had any effect on the actual
S/PDIF stream emerging from the transport.

Hence I suppose it is possible you have encountered something similar.

[snip]

. A CD-Rom vibrates quite a bit in your hand,

Indeed. However when spinning at speeds above x1 it can re-read the disc to
ensure consistent and reliable data recovery before sending out the
resulting bitstream.

so I guess this is dampening it usefully.

No idea.

The most noticeable thing is that louder passages are less congested and
shouty - they have soothed out audibly. Now I have no idea why
resonances affect CD transports, but this is without any doubt what I'm
hearing - change the damping, change the sound.

You may have no doubts, but I in turn doubt this guarantees your
perceptions are reliable guides as to any 'cause' of what you beleive may
be occurring. :-)


I suppose this is back to the debate whether 'bits are bits' or whether
the signal is complex and affected by other factors. Since it isn't hard
to try, maybe somebody else would like to replicate bolting a CD-rom
down to a 10mm slab of alu? I wonder if the measurements would be
different on any parameters.

To find out: Try making some relevant measurements! Then tell us the
results.

In principle, vibrations can make it harder for a transport to recover the
data from the disc, and there will always be a finite error rate. In
practice the actual recovery with a decent transport should be highly
reliable in normal use. Can't say much more without some relevant
*measurements*.

So in principle. Some bit errors may be emerging. Some jitter may be
affecting the result. But in practice this seems questionable. To resolve,
employ suitable measurements. Otherwise we (including you) have no real
idea if the effects you describe have anything to do with the 'causes' you
assume.

Slainte,

Jim

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