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?

BTW - Can someone point me to a not too technical article(s) on how
DACs work and why it is that one DAC can sound 'better' than another?

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

Regards,

John.

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

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html

"Jim Lesurf"

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).

** Hang on a mo:

Bose 901s produced fantastic "stereo " anywhere in the room - even with a
mono recording !! So too could Sonab speakers - leastwise if the room
had bare walls and no floor coverings.

Both these makers figured out how to turn technical disadvantage into a
MONEY SPINNER !!!!


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.


** Yep - one of the tell tale signs of a *very good hi-fi set up* is
that a mono recording sounds like it originates from a point smack between
the two speakers. Plus, if you are playing a mono LP - surface noise will
be in glorious stereo & with amazing width !!

( Leave it that way, resist any temptation to set the pre-amp to "mono" as
it is quite easy to learn to ignore the fake stereo noise as a completely
separate sound from the musical performance you WANT to hear )


May be a sign of a problem (not necessarily in either DAC,
but elsewhere in the listening arrangements).


** The OP is dreamin' ........




....... Phil

Jim,

Obviously a 'zero width sound stage' would be impossible except in an
anechoic chamber, all other rooms would have some resonance. The fact
my ESL63s are less than two feet from a hard rear wall is probably the
culprit but there is really no other place to put them.

I guess what I'm really curious about is whether this apparent
widening is a 'fault' or a 'feature' (real improvement) because it is
similar to the effect on stereo recordings that I hear as an
improvement. After listening to the X-DAC for a time then switching
back to the Quad, the sound seems a little compressed and slightly
muffled. I just wonder if I am I being fooled by some artefact that
the X-DAC is introducing to make it sound 'better' or is the fact that
instruments are more clearly defined making the perceived sound stage
wider.

I'll check out the 'Scots guide'.

Regards,

John.


On 8 Oct, 17:33, Jim Lesurf wrote:
In article om,
wrote:

Hi,
I recently picked up an old Musical Fidelity X-DACat 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 aDACdo 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 eitherDAC, 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 oneDACcan 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-DACis 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 aDACworks won't cover as it
won't know what the maker of the X-DACdid, 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 - WhatDAC(chip set?) is used in the Quad CD66?

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

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html

wrote in message
oups.com...

Jim,

Obviously a 'zero width sound stage' would be impossible except in an
anechoic chamber, all other rooms would have some resonance. The fact
my ESL63s are less than two feet from a hard rear wall is probably the
culprit but there is really no other place to put them.

I guess what I'm really curious about is whether this apparent
widening is a 'fault' or a 'feature' (real improvement) because it is
similar to the effect on stereo recordings that I hear as an
improvement. After listening to the X-DAC for a time then switching
back to the Quad, the sound seems a little compressed and slightly
muffled. I just wonder if I am I being fooled by some artefact that
the X-DAC is introducing to make it sound 'better' or is the fact that
instruments are more clearly defined making the perceived sound stage
wider.

I'll check out the 'Scots guide'.

Regards,

John.


On 8 Oct, 17:33, Jim Lesurf wrote:
In article om,
wrote:

Hi,
I recently picked up an old Musical Fidelity X-DACat 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 aDACdo 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 eitherDAC, 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 oneDACcan 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-DACis 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 aDACworks won't cover as it
won't know what the maker of the X-DACdid, 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 - WhatDAC(chip set?) is used in the Quad CD66?

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

Slainte,

Jim

--
Electronics
http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html


I seem to recall that the X-DAC had a poorly designed receiver that didn't
reclock the digital signal. This consequently made it sensitive to jitter
especially cable-induced jitter. It was one reason why a review at the time
said this DAC was so good, it would clearly show up the differences between
digital cables.......

Just for fun, you may want to try the X-DAC with different bits of cable,
for this exercise what the cable is, impedance etc, really doesn't matter,
you're listening for differences. A DAC with a well-designed receiver
shouldn't show any difference whatever the cable is, (within reason!).

S.

--
http://audiopages.googlepages.com

In article .com,
wrote:

Jim,

Obviously a 'zero width sound stage' would be impossible except in an
anechoic chamber, all other rooms would have some resonance. The fact my
ESL63s are less than two feet from a hard rear wall is probably the
culprit but there is really no other place to put them.

Indeed. With the ESL63s I use for the main hifi the 'width' for real mono
is equivalent to much less than the width of my head at the plane between
the speakers for most source material. Speakers about 1.5m apart (distance
between their closest corners) and a similar distance from the wall behind
them.

The ESL988s in the AV system give a less well defined image. But there are
various room/layout reasons for that. Different room acoustic, closer to
the far wall, etc, etc. Also dependent on precise location of my head.

FWIW I just did a check and found that a mono DVD of piano music made
a good check for this. Has the advantage that the sound is LPCM 1.0
so should ensure that exactly the same sample series is being used for
left and right.

I guess what I'm really curious about is whether this apparent widening
is a 'fault' or a 'feature' (real improvement) because it is similar to
the effect on stereo recordings that I hear as an improvement. After
listening to the X-DAC for a time then switching back to the Quad, the
sound seems a little compressed and slightly muffled. I just wonder if I
am I being fooled by some artefact that the X-DAC is introducing to make
it sound 'better' or is the fact that instruments are more clearly
defined making the perceived sound stage wider.

Hard to say. It could be an imperfection whose effect you like, or a sign
that the X-DAC is 'better' in some way. I doubt reading up on how DACs work
in principle will help as what you hear probably stems from something else.

For example: It might be that the two DACs have different output impedances
and/or coupling caps. These then might give subtly different responses when
loaded by the amplifier input. Perhaps different for the two channels with
the X-DAC. It only takes a small departure from symmetry to alter the
apparent image for double-mono if you are comparing with a very 'narrow'
symmetric case with a less symmetric one.

I've no idea of the above specific example is relevant in your case, but it
shows that an item that might be 'fine' in some circumstances could be
'different' in others. Thought of it because IIRC MF also produced a
'buffer' stage to follow a source and drive the amp. Some modern amps
seem to have input impedances I'd regard as 'low', thus possibly making any
variations in source output impedance more significant.


Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html

On Oct 8, 9:50 am, 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.

The most kely audible change when you try a different DAC, is that its
output is at a higher or lower level than its predecessor.

Many people like to think that they can reliably distinguish changes
in level as being a change of loudness, but 30 years of blind tests
say otherwise.

However, what did surprise me was that some mono recordings seem to
have this 'widened sound stage'. Is this possible?

When you are limited to subjective perceptions like "widened sound
stage", all things are possible.

Perceptions are based on memory, expectations, and the current
listening experience. IOW, all other things being equal, about 2/3 of
what you base your perceptions on is irrelevant to the current
listening experience.

Can a DAC do this
or is there some DSP or analogue tweak being used to artificially
'improve' the apparent sound stage?

Yes. Historically X-DACs have been graced with tubes. Tubes are often
used as EFX devices.


BTW - Can someone point me to a not too technical article(s) on how
DACs work and why it is that one DAC can sound 'better' than another?

YOu might do better to read up on X-DACs since they are composite
devices.

For example:

http://www.stereophile.com/digitalprocessors/1204mf/

In article . com, Arny
Krueger wrote:
On Oct 8, 9:50 am, wrote:


Can a DAC do this or is there some DSP or analogue tweak being used to
artificially 'improve' the apparent sound stage?

Yes. Historically X-DACs have been graced with tubes. Tubes are often
used as EFX devices.

That's a point which hadn't occurred to me. :-) Yes, if the DAC uses
valves in its o/p stages then these might exhibit something like
microphony, and that could inject some amount of 'stereo reverb' picked up
from the room or the structures supporting the DAC. No idea if it would be
enough to explain the report, though.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html

"Arny Krueger" wrote in message
ups.com...
:: YOu might do better to read up on X-DACs since they are
composite
: devices.
:
: For example:
:
: http://www.stereophile.com/digitalprocessors/1204mf/
:
**YOU** quoted Stereophile!? I'm aghast in disbelief after
all the nasty things you have said about this publication in
the past. BTW does this mean you actively read it now?

TT

On Oct 9, 11:09 pm, "TT" wrote:
"Arny Krueger" wrote in message

ups.com...
:: YOu might do better to read up on X-DACs since they are
composite
: devices.
:
: For example:
:
:http://www.stereophile.com/digitalprocessors/1204mf/
:
**YOU** quoted Stereophile!?

When looking for relevant information about snake oil, what better
place?

I'm aghast in disbelief after
all the nasty things you have said about this publication in
the past.

Yeah, sure. A little google searching would show that I quote them
quite frequently.

BTW does this mean you actively read it now?

Google finds Stereophile articles quite nicely.