[Gary Eickmeier]

"Audio Empire" wrote in message
...
On Mon, 21 May 2012 07:30:33 -0700, Gary Eickmeier wrote
(in article ):

The speaker disappearing act is caused by a simple image shift toward the
reflected sound from behind the actual speakers. An aerial image is
formed
in the region behind the speakers, getting the sound OUT of the speaker
boxes and creating the unmistakable impression of the musicians being
right
there in front of you performing in your room, rather than sounding like
they are flat cartoons coming from the speakers and strung on a
clothesline
between the speakers, with no depth or dimensionality.

You speak as if this is a characteristic inherent in the speaker itself.
Well, I agree that the speaker must be able to image well and "throw" a
wide
and deep soundstage, BUT - and this is all important - if the information
is
NOT there on the recording in the first place, even the world's best
imaging
speakers won't be able to produce the illusion to which you refer. Take
most
any classical recording from the mid-sixties to the late eighties and the
great majority of recordings made since then, and there is NO imaging
information on the recording. Most are, as you so aptly put it, a series
of
"flat cartoons" 'Strung on a clothesline." This is because most
recordings
are multi-miked, multi-track travesties and sound simply dreadful from an
imaging perspective. I believe that one of the reasons that audiophiles
still
revere recordings made more than 55 years ago by the likes of Lewis
Layton,
and Richard Mohr at RCA Victor, Bob Fine, Wilma Fine and Bob Eberenz at
Mercury, and Bert Whyte for Everest is because these recordings were made
with simple, two or three mike setups directly to tape with no electronic
"futzing" between the mikes and the tape. Many of these recordings have
the
soundstage information that allows for good, realistic imaging (assuming
that
the playback system is up to the task).

Yes, sure, I agree with most of that, but with some caveats.

As I mentioned, if it is a tight and dry recording it gives a "they are
here" impression. In other words, no original acoustics recorded, it places
the instruments right in the environment of your listening room, like a
player piano or something. Those images will take a position the closest up
front that your system is capable of displaying, but still should not EVER
come from the speaker boxes themselves.

At the audio club I demonstrated this with the dry, mono recording of the
human voice outdoors. I transferred it to my laptop and processed it with
Audition so that it would pan from extreme right to extreme left chennel.
This was with my experimental speakers that were entered in The Challenge.
Most audio people would expect such a dry sound to image from one speaker to
the other and come from the speaker itself when at the channel extremes. So
to prove my point, I obtained an orange cone from Home Depot so that I could
place a visual where the audience perceived the sound to be coming from. I
started the recording at stage right, and when it got to the center I asked
them where the voice was. I placed the cone as directed until everyone
agreed. It ended up centered but a foot or two back behind the line of the
speakers. Same question when it got to stage extreme left. To their surprise
the voice was coming not from the speaker but from a foot behind the
speaker - unmistakably. To me, this proves the image shift, which slightly
defies the precedence principle. But even the textbooks say that if the
reflection is strong enough there will be an image shift.

This principle can be a very powerful tool in setting up your speaker system
for imaging, but if done wrong can be a disaster of Consumer Reports vs Bose
proportions. Bose did not give correct speaker positioning instructions in
the owner manual for the 901s, inviting disaster with a strongly negative
directivity speaker (strong reflected portion of its output). CR reported a
hole in the middle and stretched soloists, as did many audiophiles. If
correctly placed by accident, they could be impressive, but if you put them
too close to the walls all of the criticisms rear their ugly heads.

Draw an image model of the problem and you can see easily what is happening.
Move the speakers closer to the front wall and depth diminishes because the
reflected image speaker gets closer to the actual one. Move the speakers
wider, and the total image (or soundstage) becomes narrower! Place them
within a foot or two of the corners, and you get a "clustering" of acoustic
images that causes this hole in the middle and six foot wide soloists. I
threw caution to the winds one fine day and pulled my speakers out from the
walls and in to about 1/4 of the room width, and all of a sudden the sound
focused itself like a camera lens and there in front of me was the answer to
many questions.

I don't know where Andrew got the impression that I disagreed with Floyd on
something. What I said was that I read all through his book for the answers
to Linkwitz's very basic questions but couldn't find specific
recommendations on radiation pattern, speaker positioning or room acoustics
except to the extent that he agreed that reflected sound was necessary in
any audio setup. In fact, I wrote to him several times and asked him
directly about these questions, and also noted the many areas in his book
that supported my IMT. I was hoping for some sort of endorsement of my
writings, but it was not forthcoming. I have found that the well-known and
respected engineers will not commit themselves on paper to any outside
unsolicited ideas, especially off the beaten path ones like mine. I had a
nice, long talk on the phone with Siegfried, but he would not write that my
ideas were answers to his questions.

Same with Dr. Bose, in case you were wondering. I have tried to get him to
come out with an advanced, audiophile class 901 speaker with a slightly
different radiation pattern, but he is more interested in the mass market
than the small group that classifies themselves as audiophiles. And of
course it is the same as with unsolicited manuscripts sent to Hollywood
producers - they will not even be opened or acknowledged, for fear of
lawsuits if they use any of your material without paying you.

So I remain a voice crying in the wilderness. So fine.

Gary Eickmeier