In article om,
wrote:

Hi,

I recently picked up an old Musical Fidelity X-DAC at an audio sale. It
seems to be a slight improvement on my Quad CD66, little wider sound
stage, fractionally more precise instrument positioning.

However, what did surprise me was that some mono recordings seem to have
this 'widened sound stage'. Is this possible? Can a DAC do this or is
there some DSP or analogue tweak being used to artificially 'improve'
the apparent sound stage?

if the input is genuinely mono then the streams of values for 'Left' and
'Right' on the CD will be precisely identical. Thus if you don't hear a
central image with essentially zero width this is an artefact introduced by
your replay system (inc speakers and room acoustics, etc). This may either
be due to an imperfection of the system, or some deliberate tampering to
alter the results, having nothing to do with 'fidelity' as such. May be a
sign of a problem (not necessarily in either DAC, but elsewhere in the
listening arrangements).


BTW - Can someone point me to a not too technical article(s) on how DACs
work

If you look on the 'Scots Guide' you can find explanations at different
levels of detail. But no doubt there are many alternatives around, and you
may prefer those.


and why it is that one DAC can sound 'better' than another?

The problem is that you first have to define "better". :-)

if you mean, "you prefer the results" we would find need to find out what
your X-DAC is doing that causes mono to have a 'wide' soundstage when no
such info is in the data on the CD. :-) The snag is that this may be due
to a flaw which a simple explanation of how a DAC works won't cover as it
won't know what the maker of the X-DAC did, or in what way it is faulty.
;-

We would also need to be confident that what you report you hear is for the
reasons you think. The 'difference' might be for some other reason for all
we know. Very easy to do this when comparing items in a domestic audio
unless you know and follow the relevant methods.

it is easy enough for two DACs to sound "different" if one has been
deliberately (or incompetently) made to alter the output. Or if one is
faulty in some way. Or if one is misused in some way. But I can't say which
you might then prefer.

BTW2 - What DAC (chip set?) is used in the Quad CD66?

Pass. Have data on the CD67, but not the CD66. They may use the same DAC,
but I don't know offhand if this is the case.

Slainte,

Jim

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