From: shetline@bbn.com (Kerry Shetline)
Newsgroups: rec.audio
Subject: Re: Losing My Religion (Was...many times tangentially removed)
Date: 11 Jan 93 16:03:31 GMT
Followup-To: rec.audio
Organization: BBN
NNTP-Posting-Host: bbn.com

In article <gmaltby.54.726742835@unpcs1.cs.unp.ac.za>,
gmaltby@unpcs1.cs.unp.ac.za (Gavin Maltby) wrote:
> My Wadia X32/3200 combination CD player supports all the interfaces.
> I started with the coax link.  I paid a fair bit for that high quality
> coax.  At the time the DAC had toslink receiver electronics installed,
> in addition to the coax link.  Comparing the two gave no conclusive
> evidence, even in a rather revealing system.  I could not justify the
> expense, really.  A friend with the same CD had the AT&T receiver
> electronics installed, and we did a comparison.  With the transport
> next to the rest of the system things were better, but not massively
> so.  Then we removed the transport to the next room (using the 6m
> optical cable).  The difference was amazing, as though we'd changed
> some major component.  I have since installed the AT&T stuff on my
> DAC, and have similar results.  It seems that the biggest, and definitely
> worthwhile, difference was getting the transport out of an area where
> it could be vibrated.
> 
> Something to think about?

I'm not sure if you are saying that you tested coax vs. optical at the long
distance, or just tested coax vx. optical at a short distance, and then
optical with the transport in another room. It sounds like the latter.

As you may have guessed, I'm not much of a believer in the idea that
vibration of a CD transport (at a level insufficient to cause mistracking)
can have any audible effect. Certainly microphonics isn't a likely
candidate for an effect, nor mechanical jitter. ('Tiptoe' through the
tulips...)

There is one very good possibility, however: Removing the mechanical noise
of the transport from your listening room. The tranport may seem very
quiet, but when compared to the levels of some noise that audiophiles pay
significant amounts of money to reduce (tiny amounts of AC hum in power
supplies, small noise shaping effects in digital processing, logic/audio
circuit interactions, etc.), the noise of the transport is probably an
order or two of magnitude higher.

Does this seem reasonable to you? If it's not too much trouble, perhaps you
could try some sort of additional experiment, like putting the transport in
the other room, but placing something on top of it to induce vibration --
like a boom box, a blender, or an electric pencil sharpener. Of course, the
level of noise that escapes to your listening room would have to be less
than the tiny (probably nearly sumbliminal) level of noise that the
transport would produce while in the listening room, so it would be hard to
know if you had a good setup. Well, it's just an idea.

Another posibility would be acoustic resonance with some part of the
transport itself -- but that's really fishing! Easy to test though: try
some other source of music, with and without the transport in the room.

If your ears are this sensitive, however, you're going have to start rating
your friends, family, and household pets by their acoustic interaction
qualities. That high-frequency absorbing fluffy cat will just have to go!
;-)

-Kerry