[Gary Eickmeier]

THE PROBLEM WITH STEREO



I want to take you on a time travel trip to an alternate present, a present
in which even more mistakes are made than have been made now, in 2016. What
mistakes? Ride with me:



Suppose that architectural acousticians were even slower than audio
engineers in catching on to what causes good sound. We go into a new concert
hall that they are designing and observe them treating the walls for great
sound. They reason that what we need to hear is just the direct sound from
the instruments because anything else bouncing off the walls all over the
place would muddy things up and dilute the imaging and everything else. They
line the front wall, the one behind the players, with Sonex or similar, to
keep the reflected sound from coming back to the audience. Similarly with
the side walls, sound absorbing materials all over the place - especially
those first reflection points, so that it will, after all, sound just as
good as our stereo recordings of them.



TROUBLEMAKERS



Things would have stayed that way except that a few troublemakers had gone
to Europe and listened in some halls that had not been treated. The sound
had a certain "spaciousness" or width to it, seeming to come from much wider
than the orchestra itself. And the tonality of the instruments! They didn't
realize that the violins and cellos had such a warmth and musicality to
them. And the percussion! It sounded a lot more important there, with all
of those reflections. The team came back and reported to the American
acousticians that maybe we DO need to hear all of those reflections that we
have been dampening and controlling. Reluctantly, the acousticians try it,
taking down all of the sound killing materials until we once again get back
to the way we know it today.



In the concert halls, anyway.



STEREO



I get it now, said one acoustician. What we should be doing is building
sound fields within the concert hall, not just the direct sound from the
instruments. If we could label these fields, we could call them the direct
sound, the early reflections, and the full reverberant field. This is all
really quite important and just the opposite of what we had been doing. Now
we can hear the full sound power put out by the instruments in all
directions, and the sound doesn't trail off so abruptly as you go back in
the hall. This is what we should have been doing all along - building sound
fields, rather than just the direct sound for the audience's ears.



"But what about stereo reproduction?" one of them asked. Our current
practice is just the direct sound from the speakers, with all reflected
energy dampened away with Sonex or clever room shapes. We have been told to
make "reflection free zones" for the primary direct sound and don't let
anything get past those first reflection points. "But this is just the
opposite from what we have learned about the concert halls" blurts one
acoustician.



Maybe we should think about this.



Yes - this principle has proven very important for the production of music,
but what about the reproduction? Why would it be any different?



Oh, that's easy. According to time honored principles, we have already
recorded those qualities of the concert hall that make good sound. Now all
we need to do is play it back and we will hear it.



Are you saying that our ears work differently for stereo than they do for
live music? The huge, complex set of direct and reflected sound fields for
live music sounds the same as the two high direct fields from two points in
space for stereo?



Well, yes, at least for the area between the speakers.



That's the best thinking for stereo reproduction today? We have just
discovered that the most important factor in the concert hall is the
building of the various sound fields within the room, but in stereo we're
going to use just the direct sound from two speakers? These two could not
sound the same.



Maybe someone from our discipline should get with the audio engineers and
explain about the spatial nature of sound - that it is very audible and must
be addressed in the reproduction just as it is for live sound or it will
sound different. That is, if they are really interested in reproducing all
characteristics of live sound.



Gary Eickmeier

[Robert Peirce]

The purpose of treating the listening room is to better hear the sound
field of the recording. If your room is untreated it adds its own
reflections. If the recording is bad it probably doesn't matter.

[Gary Eickmeier]

"Robert Peirce" wrote in message
...
The purpose of treating the listening room is to better hear the sound
field of the recording. If your room is untreated it adds its own
reflections. If the recording is bad it probably doesn't matter.

The sound FIELDS of the recording - the wide, spacious, set of direct and
early reflected and reverberant FIELDS -

cannot be reproduced

with just the DIRECT FIELD

from a pair of stereo speakers.

All of the direct, early reflected, and reverberant fields of the original
would be compressed into arriving from just those two points in space, not
from the original directions of the sounds that were recorded. This is very
audible.

That is the problem with stereo.

Gary Eickmeier

[[email protected]]

On Saturday, June 25, 2016 at 4:38:20 AM UTC-7, Gary Eickmeier wrote:
THE PROBLEM WITH STEREO
at least one set of golden ears [Gordon Holt] said that he in a very real s=
ense "heard stereo" for the first time when he experimented with extracting=
the l-r and r-l signals and sending them to rear speakers with a small tim=
e delay and moderate treble roll-off, and sending the l+r signal to another=
speaker in the center between the conventional stereo pair. I have heard t=
his improvement for myself and heartily concur with Holt on this. the only =
difference is that I find the sound field to be more cohesive ["wraparound"=
] without the time delay. this also has the effect of greatly enlarging the=
"sweet spot" or at least making the usual lateral collapse of sound to the=
nearest speaker much less obnoxious, especially if the front stereo pair a=
re toed-in.

[Gary Eickmeier]

wrote:
On Saturday, June 25, 2016 at 4:38:20 AM UTC-7, Gary Eickmeier wrote:
THE PROBLEM WITH STEREO
at least one set of golden ears [Gordon Holt] said that he in a very
real sense "heard stereo" for the first time when he experimented
with extracting the l-r and r-l signals and sending them to rear
speakers with a small time delay and moderate treble roll-off, and
sending the l+r signal to another speaker in the center between the
conventional stereo pair. I have heard this improvement for myself
and heartily concur with Holt on this. the only difference is that I
find the sound field to be more cohesive ["wraparound"] without the
time delay. this also has the effect of greatly enlarging the "sweet
spot" or at least making the usual lateral collapse of sound to the
nearest speaker much less obnoxious, especially if the front stereo
pair are toed-in.

Well, obviously amen to that. But what I am saying is that stereo as most of
us apply the term today is still a half-baked concept. We have the summing
localization from left to right down pat, but that is not all there is to
it. See, first we had mono and we never expected it to make the music sound
"real" as if the musicians were right there in our room or we were right
there at the concert. Then stereo recordings and sources came around and we
just took two mono speakers and arrayed them left to right and assumed that
that was all there was to it. The implicit assumption of how it works seemed
to be you relay the sound from each microphone to your ears as accurately as
possible with no disortion or interference from the room acoustics and
voila, realism. Recording engineers go to extra lengths to construct
reflection free zones near the speakers so that they get only the pure
direct sound to their ears as the first arrival, and that is stereo.

Well, OK, first, it is true that we will never achieve the absolute realism
of transporting us to the concert hall, because of the fundamental recording
problem, that we have to run the sound through two rooms before we hear it.
In other words, we must hear our room or acoustical situation superimposed
onto the recorded sound. And no, listening anechoically doesn't work because
the sound fields do not sound natural and the imaging will not externalize
(In Head Localization, or IHL).

But we can get closer if we understand basic acoustics and that stereo on
speakers is a field-type system, not a binaural system. Once your ears are
free to hear all sounds in front of them, with no crosstalk cancellation,
then it is a field type system and we must physically reconstruct the sound
fields within our listening rooms to mimic the spatial "shape" of typical
live sound. It has not (dare I say never?) been considered before that the
reconstruction of all fields needs to be a basic part of stereo theory. What
we need to do is position the speakers in a certain way and then cast a
certain amount of direct sound toward the listening end of the room, and a
slightly greater amount of reflected sound toward the front and side walls
of the room in the same way (spatial "shape") as it happens live. You now
have a reconstruction of the live sound that is capable of decoding the
direct and reflected sounds that were recorded by means of time of arrival.
You will get the spaciousness and depth that sound more like live because of
a simple image shift toward the reflecting surfaces, giving great depth and
a soundstage from wall to wall, rather than speaker to speaker. The speakers
will disappear as sources of the sound, and you will perceive a very live
sounding Auditory Scene, or AS, in front of you. Add some surround sound to
complete the reconstruction and you have the best that can be done with
legacy stereo recordings.

The bigger the room the better because larger rooms are more the size of the
real thing, and I use specular reflectivity on the front and near side walls
to get the sharpest focus to the early reflected sound. No sound killing and
no diffusion up front. Most of these techniques are just the opposite of
what we have been assuming all these years and would never occur to audio
engineers to try.

Gary Eickmeier

[Peter Wieck]

On Sunday, June 26, 2016 at 6:26:02 AM UTC-4, wrote:

at least one set of golden ears [Gordon Holt] said that he in a very real=
sense "heard stereo" for the first time when he experimented with extracti=
ng the l-r and r-l signals and sending them to rear speakers with a small t=
ime delay and moderate treble roll-off, and sending the l+r signal to anoth=
er speaker in the center between the conventional stereo pair. SNIPPAGE=


This is a very old solution, AKA the "Hafler Circuit" in its early manifest=
ations, and the Advent 500 Sound Space Control and/or ADS Ambient Control C=
enter in its more complex stages.=20

I have owned all three, and still maintain the Advent 500 and the Dynaco Qu=
adAdaptor as well as one Dynaco SCA80Q. The ADS and Advent units add a digi=
tal delay that may be controlled from a "small room" to more-or-less Yankee=
Stadium, which was then taken to rear speakers via a separate amplifier, w=
ith the volume-control within the Advent. The SCA80Q used passive sum/diffe=
rence circuitry to make a similar effect, the ADS Acoustic Dimension Device=
was similar to the Advent but with an on-board power-amp and slightly less=
sophisticated controls. Back in the day when the ADS unit sold for $500, t=
he Advent for $350, the Dynaco device sold for $19.=20

As to reproducing the concert hall "at home" - not possible excepting perha=
ps somewhat with headphones. Keep in mind that EARS - such as many of us ha=
ve in some quantity *between* -1 and 3 are typically deployed in pairs sepa=
rated by a few inches of jelly and bone. What they discern is a mix of many=
things all-at-the-same-time, and rely on a very sophisticated but not very=
learned wet-ware system to make sense of the incoming noise and winnow the=
desired noise from the general mass of it. In a concert hall, that is all =
well enough. There is not much between the various noises and the EARS, so =
that if the wet-ware discerns well, and finds the result pleasing, it becom=
es 'music'. Not a hard concept.=20

Consider the average listening room - AVERAGE, not dedicated-by-a-fanatic. =
It is a mix of surfaces, and includes a mix of reproducers driven by some l=
evel of electronics. The reproducers may be from a few square inches of sur=
face reinforced by clever horns and baffles (full-range single-driver horns=
) driven by fly-powered triode amplifiers of a few watt, up to several squa=
re feet of surface driven by brute-force amplifiers of a few hundred watts.=
NONE of them have the capacity to reproduce a symphony orchestra at anythi=
ng like realistic volumes as consider the total vibrating surface area of a=
n orchestra in Tutti - or a single 30' bombard pipe. Not even close.=20

So, we try to get to some pleasing noise that is close-enough to actual mus=
ic as not to drive us instantly from the room screaming in pain. Some try b=
y means of a listening room engineered to a fare-thee-well with a sweet-spo=
t about as big in cubic area as the average head. Makes for acutely uncomfo=
rtable listening, but can be nearly-headphones enough to be more accurate t=
han the alternative. Others try for a general listening area that is clean =
enough to allow for a much more general listening location (I am of this sc=
hool) and try for enough headroom (power) and speaker range (flat frequenc=
y response) so as to get most of the original signal into the room.=20

And, of course, we have not even begun to discuss the many hundreds of peri=
pheral decisions made between the performance and the replay - engineering,=
microphone placement, mixing, equalization and much more.=20

I am not beginning to suggest or imply that it is a crap-shoot. But for dam=
ned sure, it is not neurosurgery or even rocket science. What it is, is a c=
onstantly moving target being fired on with a .22 pistol with a loose barre=
l. One might hit on occasion, but that is not to be counted on as the norm.=
=20

Again, we try to make pleasing noises using what is available to us. Theory=
allows us to speculate on what might be based on what we see and expect. B=
ut the actual practice is terribly inconvenient. "Stereo" is merely one of =
many means that have a checkered history of providing pleasing noise - some=
times.=20

I guess this is why I have five (5) active stereos in operation, and speake=
rs from Maggies to AR3as and some others between, from tube to solid-state,=
and include vinyl, RtR, cassette and CD options (as well as tuners, of cou=
rse). All of them, I have managed to bring to a pleasing state, few by the =
same measures.=20

But, the problem with STEREO is that it is not LIVE MUSIC. The expectations=
of getting the latter from the former is a contradiction-in-terms. And as =
such leads either to madness or frustration.=20

Peter Wieck
Melrose Park, PA

[Gary Eickmeier]

Peter Wieck wrote:
On Sunday, June 26, 2016 at 6:26:02 AM UTC-4,
wrote:

at least one set of golden ears [Gordon Holt] said that he in a very
real sense "heard stereo" for the first time when he experimented
with extracting the l-r and r-l signals and sending them to rear
speakers with a small time delay and moderate treble roll-off, and
sending the l+r signal to another speaker in the center between the
conventional stereo pair. SNIPPAGE

This is a very old solution, AKA the "Hafler Circuit" in its early
manifestations, and the Advent 500 Sound Space Control and/or ADS
Ambient Control Center in its more complex stages.

I have owned all three, and still maintain the Advent 500 and the
Dynaco QuadAdaptor as well as one Dynaco SCA80Q. The ADS and Advent
units add a digital delay that may be controlled from a "small room"
to more-or-less Yankee Stadium, which was then taken to rear speakers
via a separate amplifier, with the volume-control within the Advent.
The SCA80Q used passive sum/difference circuitry to make a similar
effect, the ADS Acoustic Dimension Device was similar to the Advent
but with an on-board power-amp and slightly less sophisticated
controls. Back in the day when the ADS unit sold for $500, the Advent
for $350, the Dynaco device sold for $19.

As to reproducing the concert hall "at home" - not possible excepting
perhaps somewhat with headphones. Keep in mind that EARS - such as
many of us have in some quantity *between* -1 and 3 are typically
deployed in pairs separated by a few inches of jelly and bone. What
they discern is a mix of many things all-at-the-same-time, and rely
on a very sophisticated but not very learned wet-ware system to make
sense of the incoming noise and winnow the desired noise from the
general mass of it. In a concert hall, that is all well enough. There
is not much between the various noises and the EARS, so that if the
wet-ware discerns well, and finds the result pleasing, it becomes
'music'. Not a hard concept.

Consider the average listening room - AVERAGE, not
dedicated-by-a-fanatic. It is a mix of surfaces, and includes a mix
of reproducers driven by some level of electronics. The reproducers
may be from a few square inches of surface reinforced by clever horns
and baffles (full-range single-driver horns) driven by fly-powered
triode amplifiers of a few watt, up to several square feet of surface
driven by brute-force amplifiers of a few hundred watts. NONE of them
have the capacity to reproduce a symphony orchestra at anything like
realistic volumes as consider the total vibrating surface area of an
orchestra in Tutti - or a single 30' bombard pipe. Not even close.

So, we try to get to some pleasing noise that is close-enough to
actual music as not to drive us instantly from the room screaming in
pain. Some try by means of a listening room engineered to a
fare-thee-well with a sweet-spot about as big in cubic area as the
average head. Makes for acutely uncomfortable listening, but can be
nearly-headphones enough to be more accurate than the alternative.
Others try for a general listening area that is clean enough to allow
for a much more general listening location (I am of this school) and
try for enough headroom (power) and speaker range (flat frequency
response) so as to get most of the original signal into the room.

And, of course, we have not even begun to discuss the many hundreds
of peripheral decisions made between the performance and the replay -
engineering, microphone placement, mixing, equalization and much
more.

I am not beginning to suggest or imply that it is a crap-shoot. But
for damned sure, it is not neurosurgery or even rocket science. What
it is, is a constantly moving target being fired on with a .22 pistol
with a loose barrel. One might hit on occasion, but that is not to be
counted on as the norm.

Again, we try to make pleasing noises using what is available to us.
Theory allows us to speculate on what might be based on what we see
and expect. But the actual practice is terribly inconvenient.
"Stereo" is merely one of many means that have a checkered history of
providing pleasing noise - sometimes.

I guess this is why I have five (5) active stereos in operation, and
speakers from Maggies to AR3as and some others between, from tube to
solid-state, and include vinyl, RtR, cassette and CD options (as well
as tuners, of course). All of them, I have managed to bring to a
pleasing state, few by the same measures.

But, the problem with STEREO is that it is not LIVE MUSIC. The
expectations of getting the latter from the former is a
contradiction-in-terms. And as such leads either to madness or
frustration.

Peter Wieck
Melrose Park, PA

Interesting treatise Peter, but I think you are needlessly complicating
things. The main characteristics that we can hear from speakers are the
frequency response and the radiation pattern. The frequency response part is
well in hand, no problem with microphones, sources, amplifiers, or wiring.
But the radiation pattern has not yet been sufficiently addressed in any
scientific or engineering sense with respect to stereo.

But it is not just radiation pattern, it is the result of radiation pattern
w respect to speaker positioning and room surfaces that we hear. Very little
attention has been paid to all that except for the erroneous advice to
dampen out all reflections. But stereo is not a "two ears, two speakers"
system and we do NOT want to hear just the direct sound from the speakers.
That should have been realization #1. If that had been studied, then there
would be out there some advice on the unanswered questions, what radiation
pattern should we desire, and what speaker positioning, and what room
treatment. Siegfried Linkwitz posed exactly those questions to the AES in a
recent paper about 7 years ago

The Challenge to Find the Optimum Radiation Pattern and Placement of Stereo
Loudspeakers in a Room for the Creation of Phantom Sources and Simultaneous
Masking of Real Sources (Paper #7959, Oct 2009)
If this had been studied enough during the stereo era, we would have some
answers and not be making the vast majority of speakers with all of the
drivers on just the front of the speaker box.

Again, my answer is to use the walls near the speakers as part of the
speaker system in a pattern that mimics that of the typical live sound
field. It is based on my AES preprint # 2869, Oct 1989, An Image Model
Theory for Stereophonic Sound. I have now had some speakers built based on
that theory that work as predicted in that paper of some 27 years ago. Very
little else matters to audibility of your stereo system, and most of the
factors that you mention are not that much of a problem at all and can
confuse rather than illuminate the problem.

Gary Eickmeier

[Peter Wieck]

On Monday, June 27, 2016 at 7:49:51 AM UTC-4, Gary Eickmeier wrote:

Gary:

I will try to address your points as close to per-each as I am able. I am =
NOT disagreeing with you, but I am discussing the art of the possible.

All of the direct, early reflected, and reverberant fields of the origin=
al=20
would be compressed into arriving from just those two points in space, not=
=20
from the original directions of the sounds that were recorded. This is very=
=20
audible.

Yes. True. However, I am not so sure that it is possible to reproduce the e=
ntire sound-field of a concert venue without a bunch of additional processi=
ng even with the best of speakers. Keep in mind that in the concert venue, =
what is reflected and heard is delayed by some amount based on the addition=
al length-of-travel. This can be disconcerting (any sort of standing wave) =
or quite pleasant if it is somehow 'timed' to resonate pleasantly with the =
direct sound. Controlling that resonance will require a fair amount of atte=
ntion and/or processing. To-date, most systems have used a brute-force appr=
oach via electronics, or by forcing some specific sort of speaker array in =
a room of a specific shape.=20

Put another way - if a speaker is designed to reproduce the overall ambianc=
e of a concert venue by using the properties of the room in which they are =
deployed, and by careful dispersion of the sound, there is not necessarily =
any guarantee that the actual venue matches to the actual room such that th=
e results are pleasing. OR - the needs of the speakers in terms of the room=
are so specific that the room must be of specific dimensions and of a spec=
ific nature with specific surfaces and the listener in a specific location.=
Or, conversely, the speaker(s) must be designed to the room. Either is rea=
sonable if a unique system is acceptable.=20

But it is not just radiation pattern, it is the result of radiation patt=
ern w respect to speaker positioning and room surfaces that we hear. Very l=
ittle attention has been paid to all that except for the erroneous advice t=
o dampen out all reflections. But stereo is not a "two ears, two speakers" =
system and we do NOT want to hear just the direct sound from the speakers. =
That should have been realization #1. If that had been studied, then there =
would be out there some advice on the unanswered questions, what radiation =
pattern should we desire, and what speaker positioning, and what room treat=
ment.

Sure. And I do not want to commit the fallacy of begging the question. Howe=
ver, what is there to control the additional radiation pattern so that it a=
ctually resembles the original sound in the first place given the limitatio=
ns of two channels and two speakers? How is that translated to the speaker =
in such a way as the drivers know what they are to do with it? Again, the i=
ssue of how the reflections resonate with the original signal is the first =
clue as to the difficulty of both recording AND reproducing this. Brute for=
ce has been the process to date, from the simple Hafler Circuit to systems =
with more computing power than the space shuttle.=20

The Challenge to Find the Optimum Radiation Pattern and Placement of Ste=
reo Loudspeakers in a Room for the Creation of Phantom Sources and Simultan=
eous Masking of Real Sources (Paper #7959, Oct 2009)=20
If this had been studied enough during the stereo era, we would have some=
=20
answers and not be making the vast majority of speakers with all of the=20
drivers on just the front of the speaker box.

Back in the days of Vilchur, Allison, Kloss and the Boston Sound in general=
, it was never expected that anyone would sit practically on top of the sp=
eakers. "modern" speakers evolved from other sound systems, primarily from =
the Cinema, where there was a fairly large distance between the user and th=
e source. Such speakers were typically massive horns set behind the screen =
and did well enough for the purposes - but never pretended at anything like=
high fidelity. Vilchur developer the acoustic-suspension concept which rei=
nforced the bass with sufficient accuracy that the mid and treble could be =
made powerful enough to compete in one speaker. Ever look at a vintage cine=
ma speaker? One designed to be driven by a pair of 6L6s in PP? they include=
an amazing amount of woodwork, and perhaps three drivers, all horns. No cr=
ossover to speak of either.=20

All of a sudden, all that could be crammed into a tiny little box. And AR (=
and others) used to demonstrate their speakers in small concert venues by p=
lacing them on stage with the musicians and switching between them. In many=
cases the (probably carefully chosen) audience professed not to be able to=
tell the difference. So, the front-facing speaker is not the prima-fascia =
problem. It is how they are deployed in our listening venues and how we use=
them.=20

AR (and others) started to recognize this issue fairly early on, and starte=
d 'messing' with the design of their speakers. The 10=CF=80 speaker used co=
ntrols for each individual driver to "tune" it to the room and even tune it=
to locations not directly on a wall or on the floor. They experimented wit=
h multiple drivers arrayed at angles (MST/LST/LSTII), sub-sat systems (Athe=
na), holographic systems (M4,5,6), planar arrays with side or down-firing w=
oofers and the tuning options of the earlier series (9/90/LS) and much more=
.. Point being that they did recognize that few individuals could have a roo=
m approaching 4,000 cubic feet and fewer had full freedom to place their sp=
eakers. Magnepan, KLH, Accustat and a several others designed planar speake=
rs with square feet of surface radiating front and back, magnetic and elect=
rostatic...=20

I think that speakers (and other transducers) are the last great opportunit=
y in audio reproduction. Electronics are done. Tuners are done. Most everyt=
hing else is done. But I also think that your research needs to move somewh=
at away from theory and address the very real aspects of placement, room ac=
oustics and speaker array to address the incompatibility potential between =
the actual performance venue and the reproduction venue. I think that much =
of this discussion involves angels and pinheads... and without Deacon Musrh=
at available to do the actual calculations, direct experimentation will be =
much better than theory. I remember your previous post on speaker design, a=
nd that you had realized the design and were experimenting with it. THOSE r=
esults will be the proof of the pudding (in the eating).=20

I use AR or Maggie for most of my references as I am most familiar with the=
ir designs and have owned or own many variants. But, they are only two of m=
any, of course. And as a complete aside, my 12 year old granddaughter has m=
y Revox sub-sat system as her room is incredibly difficult for speakers. Th=
e sub-woofer found a convenient location serving as a small table, and the =
mid-tweets were small enough to allow placement where they did the most goo=
d. She is thrilled with the sound (an all-Revox system as it happens) and h=
as greatly reduced the Bieb for actual classical music and more.=20

Peter Wieck
Melrose Park, PA

[Gary Eickmeier]

Peter -

Without re-quoting the entire thing, which is available above obviously -
another great and interesting post. But let me concentrate on just one
aspect of this speaker-room interface problem.

Most (normal) audiophilles who haven't studied all this will not know the
difference between the "spatial" and the "temporal" characteristics that you
discuss. But we must differentiate the two because the spatial is the much
more important and audible one that has not been studied enough. The spatial
means the angles from which the various sound fields arrive at the listener.
For example, the direct comes straight from the instruments (or speakers),
the early reflected comes from a much wider and deeper set of reflections
from the soundstage area but with a significant and important time delay,
and the reverberant comes from all around, evenly, with (hopefully) a smooth
decay to inaudibility, considered to be 60 dB below the loudest sounds. When
we record we should try to record not just the instruments but also the
early reflected sound as part of the whole soundstage, helping to flesh out
the full sound power of the instruments and giving us the timbre of the
instruments and the perception of spaciousness that we hear live.

This perception of spaciousness - very important to stereo and the musical
enjoyment, live or reproduced, is caused by the physical placement of those
recorded reflected sounds from angles that are similar to the original. I do
it by reflection, but you could do it with extra speakers placed near the
front and side walls of a smaller room. Anyway, it is the directions from
which those sounds arrive that is involved in this perception of
spaciousness. This cannot be reproduced by the direct speakers no matter how
good they are, it must come from the radiation pattern by means of
reflection or from those extra speakers.

OK, so the temporal aspect is also important, but it does not come from the
temporal delay of those reflections we were just talking about above. It was
actually contained in the recording, both the delay of the early reflections
and the full decay of the reverberant field. You will often see the
criticism of a direct and reflecting type of speaker that our home rooms
are not as big as the original, so it can't work. But now I hope you (all)
can see that if we address the spatial part, the temporal will take care of
itself.

Moral of the story, we must learn to separate in our thinking the spatial
from the temporal characteristics of sound fields.

Gary Eickmeier

[dolph]

If your room is untreated it adds its own
reflections.
192.168.l.2