Re: [microsound] M-S micing

[Aaron Ximm <ghede@xxxxxxxx>]

First consult the nets:

 http://www.sounddevices.com/tech/ms_stereo.htm
 http://www.paia.com/msmicwrk.htm
 etc.

The main advantages are mono compatability, ease of setup/use, and the
ability to adjust the stereo image in "post."

Mono compatability means that when a stereo signal is played back with
both channels on a single speaker (e.g. a television speaker) it is not
compromised. Alternative techniques for recording true stereo,
particularly spaced microphone techniques, typically produce "comb
filtering" that is quite distracting and undesirable; with M/S recordings
the side channel components [effectively] collapse (cancel out) and the
center channel remains [effectively] uncolored.

The usual defining characteristic of the central (mid) mic is not
that it is "mono" but that it is directional. Omnis can be used as the
center channel but this is not as common; the cannonical M/S array is a
cardioid mic as the M element and by definition a figure-8 as the S
element.

M/S pairs are "easy" to use because they are located in the same position
(compare spaced techniques such as ORTF or A-B omni); they can be housed
in a single windscreen for example. For field recording this is a huge
win.

Varying the ratio of M and S components changes the perceived width of a
stereo image on decode. The more mid, the "wider" the image.

It is possible to buy single microphone bodies with multiple elements
which use M/S -- often these mics will "decode" the signal to normal L/R
stereo for you, eliminating the need for M/S decoding in post -- but also
not permitting it. It is usually most desirable to record to M and S, but
monitor in R/L -- the Aaton Cantar and Sound Devices 7 series recorders
for example allow decoding to the headphones while recording raw M and S.

You can construct an "M/S decoder" on a reasonably functional mixing board
(with the ability to sum to busses and phase reversal buttons), but there
are free VST plugins (and purchasable plugs I'm sure) that will do this
for you as well. This is a very computationally inexpensive operation, but
is not built into many DAWs/editors as a basic function in my experience.

According to [very accomplished] field recordist Bernie Krause, in his
rigorous testing M/S stereo rated highest among common stereo recording
techniques in almost all subjective regards such as perceived depth of
field, sharpness and stability of perceived sound source location, etc.

When considering mics for M/S it is important that the M and S mics be as
similar in character (and quality) as possible; this in practice is quite
difficult because there are not so many figure-8 pattern mics available
for field use.

One mic receiving a lot of kudos on the naturerecordists list is the Rode
NT2-A:

 http://www.zzounds.com/item--RODNT2A

Its main drawback is that it is quite heavy which makes custom mounts and
windscreening a necessity.

Note that my familiarity with M/S isfor field recording.  M/S is not
particularly common to my knowledge as a studio recording technique --
partly because except for particular applications, "stereo" is usually
constructed from discretely miked elements rather than recorded directly.

Sennheiser makes a variant of their popular MKH416 shotgun which includes
an S element as well (the MKH418S); in accounts I've read the side element
has been found to be lacking (quite noisy and not as sensitive as the
center element). For non-quiet sound sources it might be very convenient
however.

 best regards,
  aaron

--

  ghede@xxxxxxxx
  http://www.quietamerican.org

  |  quod omne animal post   |
  |  cogitum est triste...   |


---------------------------------------------------------------------
To unsubscribe, e-mail: microsound-unsubscribe@xxxxxxxxxxxxx
For additional commands, e-mail: microsound-help@xxxxxxxxxxxxx
website: http://www.microsound.org