[Audio_Empire]

In article ,
"Gary Eickmeier" wrote:

In the previous thread about models for how stereo works, why it doesn't
sound more realistic, whether the recorded signal contains enough
information to reconstruct the performance in another room, and so on, the
discussion gets confused with personalities, experience with different
systems, taste vs something more scientific, theories vs hypotheses, and on
and on until the whole discussion skids to a halt and nothing is transmitted
or received. Well, I am here now to change all that.

A tautology is a statement whose truth is so obvious and undeniable that it
requires no proof. In logic, it means a statement that cannot be denied
without inconsistency. I have a simple example that might explain some
things about realism in sound reproduction.

Suppose that you just love Oscar Peterson's jazz piano playing. While he was
still with us, he made some recordings on a player piano like the Yamaha. It
records every keystroke, every pressure on the keys, perfectly, so that on
playback it is the same as when it was recorded. So imagine that you had one
of these pianos and invited him over to play and record same. He sits down
and plays. He leaves, later dies.

It is a tautology that if you play the recording of his keystrokes on the
same piano in the same room it will be a perfect reproduction. I think this
one will survive even Dick Pierce.

It might survive Dick Pierce, but it doesn't survive Audio_Empire.
Presently, the very best way of doing what you postulate, above is via
a system devised by a North Carolina computer company called Zenph.
They take a (commercial) recording of an artist and run it through a
computer program which registers each piano note played, analyzes it
for pitch, amplitude duration, and probably a number of other
parameters. The computer then turns that information into piano
keystrokes that mimic the information gleaned from the original
performance. They have then built a device that can exactly replicate
those keystrokes when placed in front of a piano (sort of like the old
vorsetzer from the late 19th, early 20th Century). They took this
player replicator to Toronto Canada to the very studio where the
recording they used was made by Gould in 1955. Not only was the studio
exactly the same, but the piano they used was the same piano as well.
They then had the piano tuned to exactly the same state of tune as
Gould's was on the recording dates. Then they invited people from the
Gould fan club to come and hear the "re-performance" of their hero's
most famous recording, the 'Goldberg Variations' by Bach. After the
performance (which was hailed by the assembled acolytes) they recorded
the performance using modern mikes for Sony SACD. I have that SACD and
I also have the original 1955 mono recording of that performance and
I have to say that, ignoring the sonic attributes of either, I'd have
to say while the performances are very close, they are not exactly the
same.


But why exactly will it sound the same? I mean beside that it IS the same.
It will sound the same because the sound that is played back will have the
same frequency response, radiation pattern, loudness, and position in the
room as the "real thing" did when Mr. Peterson actually was playing it.

To a certain extent yes, if we ignore the difference in accuracy
between Peterson's original playing and your Yamaha Disklavier's
registration of that playing. It's not all that accurate, believe me.
Like It's 19th century forebearer, the Vorsetzer, The Disklavier makes
keystroke "recordings" that are close enough to give lifelike and even
thrilling piano concerts right in one's own home. In fact, had I the
room in my home, I would have bought a grand piano and had a
Disklavier installed in it years ago! But that doesn't say that I
believe the system to make perfect registrations of a player's
performance.

So what? Is there a lesson here somewhere that can be applied to audio? Er,
well, yes of course. Let's try to do this thing with speakers instead of a
player piano. I am going to close-mike the piano while he plays, with some
high quality microphones and even do it with some separation between the low
and high keys so that I can delineate their spread. Sometimes even that is
not necessary, because we don't really hear that in a live situation, we
just hear the sound board coming out of the top and reflected from the
raised lid, but never mind for now, just suppose that we have recorded the
piano on digital, OK?

Not OK. Why not mike the SPACE that the piano occupies rather than the
piano. And that idea of "some separation between low and high keys" is
wrong in every way, Gary, and you should know this. The type of miking
that you seem to be advocating here will result in a piano 12 ft wide
with none of the venue ambience that gives a piano its fulsome sound.

OMG, this recording contains NO information about where the piano is, or the
multiplicity of reverberant effects from all directions that it made in the
room, NONE of it. What's a body to do?

That's better. You were setting up bad example on purpose for
illustrative purposes. Good boy!

We plow ahead, undeterred. What the hell do we do with this recording, now
that we have it? Play it back "accurately" as is current engineering
thought, or go for "realism" so that it sounds like the piano is right there
in the room with you?

The "accuracy" team puts a speaker where the piano was when it was recorded
and aims it toward the listener. This speaker is perfect - flat frequency
response, no distortion, time aligned, the works. But somehow, it just
doesn't sound the same. What is the difference? What more can we do than
play the sound back with perfect accuracy?

Well, if Jens Blauert, Mark Davis, Amar Bose, Art Benade, Gary Eickmeier and
many others are right, it is because the playback does not have the same
radiation pattern as the original piano. So the theory is, if we could
figure out how the piano makes sound into the room - what frequency
response, radiation pattern, direct to reflected ratio, and so on, the
original had, and we could approximate that in the speaker or speakers, then
it would HAVE to sound the same. There is no more that we can do with this
signal that is audible, than play it back with the same response, rad pat,
etc etc.

I don't agree with Amar Bose and others here (I have always thought
Dr. Bose was a bit of a quack and snake-oil salesman, and his products
have always been a triumph of marketing over substance). Bose might
have a point if recordings were designed to bring a performance into
one's listening room. They're not. At best, they are designed to
transport us, the listeners, to the venue where the performance took
place, and at worse they are designed just to allow the listener to
merely hear all the instruments without any thought of a soundstage or
any venue ambience. The microphone, correctly used, captures the space
that the instrument or ensemble occupies. If all you want is the
instrument sound. you might as well Frap (use contact mikes) all the
instruments and be done with it. I've heard that done... I don't want
to hear it again!

Is there something in this allegory that can be applied to the general
situation, and maybe show a path to some improvement in our playback
systems? We saw that if we could model the playback spatial qualities after
the real acoustic event, it would sound more real, and that if we paid no
attention to those characteristics or didn't know about them or beleive
them, then it would emphatically sound different from the original.

Your conclusion is faulty because it's based on facts not in evidence.
We do not see any evidence that proves to us that if we could model
the playback spatial qualities of the instruments after the real
acoustic event that it would result in more realistic sound from our
stereo systems. It's quite a leap in logic to go from an example of
someone like Oscar Peterson playing on a Disklavier and then playing
that Disklavier on the same piano in the same space and sounding
identical to the real performance, and then somehow transferring that
(mostly) truism to a performance in a living room playing a commercial
recording. IOW, your Oscar Peterson example proves only that Oscar
Peterson sounds like Oscar Peterson when playing the same piano that
he played before, Whether he plays in person or via an accurate player
piano device. It does not prove or even infer that this experience is
transferrable to your ideas about sound reproduction.

Even if we could prove that what you postulate is true, it's simply
not doable. Every recording is different and each brings it's own set
of acoustic parameters to the table. Short of using some technology
that embeds digital information about the acoustic signature of the
recording being played in that recording. And having done that,
playing said recording and data back through some system that can,
somehow, physically rearrange the room and speakers to conform to
those embedded parameters, I don't see how it could even be
implemented.

Yes, I think there are some very valid and very important lessons there. It
has to do with theories of reproduction, models, what is audible about sound
in rooms - whether there is anything more scientific we can do than have
preferences for this or that.

If only someone would come along and put it all together for us...

Gary, all of that research has been done. In the 1930's Bell Labs did
experiments with up to THIRTY channels of sound (they couldn't record
30 channels in those days, so they had musicians in a soundproof room
with 30 microphones feeding 30 speakers in another room). They'd move
speakers and change the room around a thousand different ways trying
to get what we would call a holographic sonic image of the musicians
playing in that other room. Out of these experiments came the final
realization (after continuing to remove mikes and speakers one at a
time) that two channels and two microphones and two speakers were
actually ideal for stereo.

Gary, don't you think that If the Bose's concept of "direct-reflecting
Sound" had any real merit beyond its marketing appeal, that it would
have gained some traction in the industry? By that I mean don't you
think that some others company would have, in the ensuing years,
copied Bose's principle to make similar, competing products? Yet in
the almost 45 years since the 901's first broke cover, no one has ever
tried to replicate Dr. Bose's product or use any of his concepts in
other products.

BTW have you ever heard the MBL Radialstahler 101 or the X-Treme?
These speakers (as closely as possible with current technology) mimic
the physics ideal of the perfect loudspeaker being a pulsating sphere.
The MBLs are (mostly) omnidirectional and yet they throw pinpoint
images. They are among the best loudspeakers I''ve ever heard. But
then so are the latest Wilson Alexandrias as well and they are just a
set of cones in boxes. And the M-L CLX is the most transparent
loudspeaker I've ever heard. There are lots of paths to audio nirvana
it seems. All of them out of my reach...... 8^)

Audio_Empire