Mind Stretchers
On Thu, 14 Jun 2012 03:46:37 -0700, Sebastian Kaliszewski wrote
(in article ):
Audio Empire wrote:
On Wed, 13 Jun 2012 05:53:45 -0700, Gary Eickmeier wrote
(in article ):
"Audio Empire" wrote in message
...
True, but since the microphones, in a correctly miked stage performance,
are
up on the stage (or hanging over it), that is the perspective that you are
capturing - "the closest seats". I have some British made AmbiSonics
recordings where the mikes are quite distant from the stage. The effect
isn't
very appealing
Not quite. As I alluded in one of my quaint analogies, we do not perceive
the sound from the perspective of the microphones.
However you "perceive" it, that's the perspective that the microphones
capture. We call microphones "surrogate ears" but that's a misnomer. Our
ears
are connected to our brain which makes all the interpretive decisions about
what and how we hear. So the mikes are, essentially "brainless" they are
pre-set to determine the field of "view" that the microphone "sees". It
intersects a sound field and turns that part of the field that strikes the
diaphragm into an analogous electrical signal, that's all it does. The
recording engineer makes the decision about how far back and how high the
mikes are placed. I have found that in most auditoriums, for a symphony
orchestra or concert band, the correct mike location is about 10 feet over
the conductor's head and about 5 ft behind him. This gives the "presence"
effect of about the third/fourth-row center. Further back, the orchestra
seems more distant and without the brain's ability to focus on specific
sounds, the microphones start to get swamped with hall ambience (not to
mention audience noise). The stereo mike over the conductor's head
technique(using, of course, a pair of cardioids on a stereo "T" bar seven
inches apart and with the axis of the microphones 90 degrees apart or a
single stereo mike configured either as above, or in an M-S configuration)
gives, what is in my opinion, the best, widest, and deepest stereo image as
well as the proper listening distance - I.E. the proverbial "best seat in
the
house".
We place the microphones
closer to the soundstage than a good, typical listening position, not
because we wish to hear the concert as if suspended nine feet above the
conductor's head or two feet from the lips of the mezzo soprano, but
because
when we play it back we will be playing it from speakers that are placed
at
some distance from us, so that the perspective becomes correct again. As I
have also said, this is the opposite of binaural theory, in which you want
to place the head at a good listening seat, because you are going to be
capturing just that perspective, and recording the entire ambience of the
original hall from that position.
I disagree. "I" place microphones in order to get the proper "presence" for
the type of performance I am recording. IOW, the proper balance between
direct and reflected sound. I want to hear some ambience, yes, but I don't
want so much ambience in a recording that it makes the recording sound,
through speakers, on playback, like we're listening to the concert from out
in the auditorium foyer! It's pretty easy to make that error and lots of
amateur recordists make it. That's pretty much my only consideration in
placing mikes. Now, the kind of mike I use depends upon a number of things
and these decisions come with experience. I can walk into a venue I've
never
recorded before and within minutes know exactly the right spot for the
mike(s). There's nothing magical about this ability, it's just experience.
But think a little about it! Your mikes are generally closer to orchestra
than
that 4th row seat. If you placed your mikes at 4th row ceneter seat position
it
would be all wrong.
Of course it would be all wrong. Again, microphones are not ears. They don't
"hear" anything - they pick-up sound and they do it in a certain way. Since
they can't focus on what they "want" to heat, like a listener in the 4th row,
the recording engineer has to focus the mikes for the listener. To get the
illusion of the 4th row, center, the mikes have to be, physically, much
closer than that.
So something is causing the perceived perspective to move
friom 10ft above 5ft behind conductor into that 4th row seat. Reasons are
rather
complex. Part of it could be that listeners are used to listen from a seat
not
hanging above conductor -- so listener brain moves the image to what it
knows.
But part of that could be simply the effect of listener surroundings. Both
ion
concert vanue and in ones listening room there are close surrounding which
affect sound coming to our ears.
It;s merely the difference between the ear's ability to focus on the sounds
it wants to hear (and to a certain extent, ignore those it doesn't) and a
microphone which merely picks up any sound that is is present whether its
wanted or not. Simply put, the closer to the performers, the more source and
less ambience and vice-versa.
By the way, i've done experiments (during rehearsals, of course) on
microphone placement, and I've found that level with the players heads or
high overhead, doesn't seem to matter much. The sound field is fairly
hemispherical, with that "sphere" being modified by the concert shell (if
any) and or the curtains lining the stage. I've also tried spaced omnis,
coincident miking, A-B, X-Y, M-S, ORTF, the "Decca Tree" etc, I've found
that X-Y and M-S work best for large ensembles, and I'd give the edge to M-S
when the "S" microphone is an omni and the "M" microphone is cardioid. One
can't use that when recording an ensemble before a live audience, however -
too much "audience participation". In that circumstance, I resort to X-Y and
perhaps M-S where the "S" microphone is figure-of-eight pattern.
Now when I record small jazz groups in clubs, I use a totally different mike
arrangement. Then I go Rudy Van Gelder all the way. I close mike each
instrument in order to attenuate (as much as possible) the audience noise. I
end up with three channel mono (left, phantom center, right), but that's
traditional for jazz recordings anyway. OTOH, if I'm lucky enough to be able
record a small jazz ensemble in someone's home, or in a club that's closed
(and therefore quiet), I resort to a stereo mike technique - which even the
musicians agree, is much more satisfying to listen to.
In stereo, a field-type sytem, we are going more toward the capturing of
the
direct and early reflected sound from the region of the proscenium, and
just
enough of the reverberant field to give the "flavor" of the original hall,
I think I said that.
but realizing that it will be mixed with the listening room acoustics
because of this distant placement of the speakers.
In my experience, this is totally irrelevant. The average listening room
adds
so little, acoustically, to the playback that I don't even think about it.
Don't conflate not thinking about something with that something having
neglibile
effect.
No, of course not. I'm not conflating anything. I said what I meant. Most
audiophiles' listening rooms are OK with, what turns out to be pretty much
the right amount and mix of soft and hard surfaces. Occasionally one runs
into a problematical room for an audiophile, but not often. Most audio types
have fixed the worst offending rooms.
At any rate, I've never listened to my own recordings in a room that changed
the way they sound in any substantial or important way. I tend to listen
around most room acoustics. They are, to me, at best, a very tertiary effect.
To come to that conclusion you'd need to compare your room with an
anechoic chamber. I wouldn say that anechoic chamber is a thing which you'd
easily ignore while being there -- yet it is the thing which would add
neglibile
amounts to reproducend sound coming from speakers.
Unfortunately, it would be difficult to listen to a system in an anechoic
chamber. First of all, you'd have to listen, nearfield to a system playing
quite loudly because the anechoic properties of the room would suck-up all
the sound!
[...]
The direct sound part undergoes a harmless image shift toward the
side and rear of the speaker, while the later and more sustained tones
take
on a spatial broadening effect that can make the recorded early
reflections
seem to be coming from the appropriate wall of your room. A greater
impression of depth of image is caused by the simple fact that the
speakers
are pulled out from the front wall into free space, and the reflected
sound
comes from behind them. All of these effects have been reported in speaker
tests in the magazines, but they have no idea what causes them.
Please show me some formal studies that back up this "notion" because my
experience with home Hi-Fi tells me that this is wrong. You're going to
have
to prove it with more than just endless reiteration
Excatly my issue with Mr Eickmeier's theory -- it lacks physical and
psychoacoustical explanation. And/Or a support off a set of properly
controlled
listening tests (there is just one result and only against some narrow set of
speakers -- a set of Linkwitz Orions -- i.e. dipoles, and some more-or-less
generic set with some experimantal(?) digital room correction).
I've heard Linkwitz' Orions at a "Burning Amp" show in San Francisco. They
sounded pretty good in the large-ish room that they were playing in. I must
say that I was impressed with what I heard.
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