[Audio Empire]

On Sun, 26 Jun 2011 06:16:26 -0700, Gary Eickmeier wrote
(in article ):

Audio Empire wrote:

Actually, you need three identical channels )including speakers to
get these three- channel recordings to sound correct. They have
spectacular soundtage even though three omnidirectional mikes
(L-C-R) are wrongheaded in my opinion. X-Y or M-S or other true
stereo techniques is always the way to go for real stereophonic sound.

Uh-oh - I think we may have argued about this one before, but.... curious,
why would you characterize X-Y or M-S as "real" stereophonic sound? What
sort of theory of stereo are you operating under? Anything deeper than
Blumlein's patent?

Gary Eickmeier


The smart-ass answer is this, Do you have three ears? Are your ears 15 ft
apart? No, to both. You have two ears and your ears are about 7 inches apart.


Kidding aside, the more scientific answer is that spaced omnis aren't phase
coherent. The reason why early stereo recordings by people like Fine and
Eberenz (Mercury) and Lewis Leyton (RCA) were initially three channel spaced
omnis is so that the center mike could be used to produce the monaural
version of the record (these were the days of "dual inventory" in which both
a separate mono and stereo record were sold of the same title). One couldn't
just sum the L+R mikes together to get mono because the phase anomalies
would cause cancellations. It was later discovered that mixing the center
channel equally into both the right and the left channels yielded a more
stable center image.

It was known that X-Y, or A-B cardioids would yield a phase coherent stereo
recording that would sum to mono perfectly, and result in much better imaging
but many felt that the flatter frequency response (off-axis) of the spaced
omnis would override any advantages in soundstage and mono compatibility
afforded by using cardioids. Some record companies such as British Decca and
DGG used M-S miking and that was also phase coherent, RCA eventually, and for
a short time, changed over to X-Y miking (before going to
multi-miking/multi-channel). I once asked Bob Fine (at a NYC Audio
Engineering Society Convention in the 1970's) why he stuck with three spaced
ominis even after modern cardioids improved enough to make them viable from a
flat frequency response standpoint. His answer was a practical one. He
acknowledged that while X-Y, A-B and M-S were better, his three spaced omnis
were something he knew intimately, and was comfortable with. He also felt
that the spaced omnis picked up more hall sound and the center mike was
largely responsible for the famous "Living Presence" Mercury sound and didn't
want to change that. He's right about the omnis and hall sound. Cardioids
have such attenuated pick-up from their backsides that if you want real hall
sound you have to use auxiliary microphones placed out in the hall. But this
only works if you are recording in an empty hall. If you are recording a live
event, you want the isolation from the audience sound. Believe me you'll
still hear them applaud on the recording, you just won't hear every cough and
program rustle.

There are lots of differing opinions about how recordings should be made.
Just because someone works in the business professionally and successfully,
doesn't mean that they are "right". A good case for this was when I
confronted RCA producer J. David Saks about his 48-channel,
microphone-per-instrument method of recording the Philadelphia Orchestra. I
said that I thought his recordings sounded simply awful. They had no depth,
and the instruments didn't sound real because, in my opinion, in order for a
group of musicians to coalesce into an orchestra, the individual instruments
must "mix" in the air between the ensemble and the listeners (or microphones)
and not in an electronic mixer. I also pointed out that instruments captured
close-up did not the sound the same as they do at a distance.

Saks' answer was that he wasn't looking for "realistic" orchestra sound, he
was aiming for "better than real". How do you argue with a wrong-headed
attitude like that?