[Andrew Haley]

Audio_Empire wrote:
On Monday, October 28, 2013 5:27:08 AM UTC-7, Andrew Haley wrote:
Audio_Empire wrote:

On Sunday, October 27, 2013 6:39:53 AM UTC-7, Andrew Haley wrote:

Surely, if a transparent DAC can be made for dollars, it makes sense
to assert that any DAC which its not transparent is defective. I
think I'd be quite happy to suggest that if two DACs can be
distinguished by listening then at least one of them must be
defective. Of course, I could be proved wrong by a properly-
conducted blind test.
Andrew.

The problem here seems to be with the term "transparent".

I'll define what I mean: any ADC/DAC that cannot be distinguished from
a piece of wire in a listening test is transparent.


Yes, that is the accepted definition. However, I can tell you, we
aren't "there" yet. While that would be an impossible test to
actually perform on a D/A converter,

Eh? Surely it's easy.

the very fact that all D/A converters sound slightly different from
each other

It's not a fact; not one that has been esatblished, anyway.

tells us that we aren't at that point (unless we can agree that
different pieces of wire "sound' different from each other -
something that I dare say that none of us is prepared to assert.

And it may be that all current DAC chips are themselves so close to

Yes, but techniques exist in the world of instrumentation to reduce to
reduce artefacts way below thresholds of hearing. Audio is easy when
compared with, say, measuring nanoamps in a noisy electrical
environment, as in an atomic force microscope.

Good point. And while many modern electrical components do have
specs that put artifacts below the threshold of hearing (the LM49710
and equivalent family of op-amps come to mind here), not all devices
made from such components have ALL of their artifacts banished to
the realm of inaudibility -yet. I'm also not convinced that ALL DAC
designers are striving for complete transparency, but are striving
for designs that they think "sound good".

I don't doubt that for a moment.

Maybe, maybe not. The only way to try is to listen. I will note,
however, that discrete construction is a spectacularly bad way of
making a hybrid component like a DAC: it's much harder to get the
accurate matching of components that you need.

I think that companies who build their own DACs from scratch are
playing on a naivet? on the part of the audiophile who might
remember when ICs for audio simply weren't very good for the
application (709 op amps, anyone?).

Exactly. It's the desire to be different, and to rise above the hoi
polloi. The irony of that is that the only way to do so with a DAC is
to make something that's worse, objectively speaking.

I certainly remember when a decent microphone mixer used
resin-potted, discrete component op-amp modules to get the low noise
demanded by recording studios simply because Integrated Circuit
op-amps couldn't cut the mustard. Then again, maybe companies like
MSB and dCS make their own DACs these days simply to justify their
astronomical prices. Whatever the reason, I suspect that hand
selecting from a Burr-Brown or ESS SabreDAC (etc.) IC product would
give at least just as good of a performance as hand-tweaked,
hand-selected discrete component D/A converter modules.

Almost certainly, I would have thought. Getting the low noise of a
really good IC is going to be very hard with discrete hybrid
construction. And how much of such a converter really is discrete,
anways? I bet most of the digital stuff isn't.

The problem is that while I'm sure that audio groups, both formal
and informal, the world over have conducted DBT tests to determine
the audibility of digital to analog conversion, there seem to be no
definitive studies that once can cite.

Why should there be? It's not as if the distortion caused by
converters is special. There's no reason to believe that DAC
distortion will [be] audible at thresholds below distortion caused
by any other component.

I don't think that's the point. The point is that there are two
equally passionate schools of belief with regard to DACs. Once
school says that all DACs are so different that one needs to choose
one based on how they sound in one's system. The other school of
thought says that they all sound alike because any criterion which
would contribute to a DAC having a sound of its own is, today, in
modern designs, well below the threshold of audibility. This second
school maintains that there is no reason to spend more than a few
dollars ( I believe $40 was mentioned) on any DAC for that
reason. One of those two camps is wrong. Some definitive DBT results
would do much to put this debate to bed.

No, they wouldn't, because certain passionate people would use special
pleading in an attempt to show that audio is, somehow, immune from
double-blind testing.

Yet audio researchers such as Lipschitz and Vanderkooy, or Meyer and
Moran have not undertaken to address this question. Indeed, a search
of AES papers yields no results that address this question in any
direct way. That means while people in the strictly objective camp
can CLAIM (and some have done on this forum) that DACs must sound
the same because all artifacts have been rendered below audibility,
but they can produce no more proof that this is the case than can
the most dyed-in- the-wool subjectivist that All DACs sound
different and that these differences aren't subtle.

It's not up to them, because it's almost impossible to prove that
something doesn't exist. Surely it's up to those who believe in this
mysterious effect to provide some evidence that it does. But what
would be the advantage to them? It wouldn't increase sales.

Andrew.