At 9:16 AM +0000 9/1/08, Greg Simmons wrote:
>--- In
><naturerecordists%40yahoogroups.com>
>Kim Cascone <> wrote:
>
>> also, while having dinner with a film sound guy in Paris he said
>that
>> most location recordists in the European film industry have
>abandoned
>> M-S for XY and A-B
>> not only because of the decoding mess but because people
>complained
>> about the 'faux stereo effect'
>
>One of the problems that film and television people have with MS is
>the concept of mono-compatibility and how you interpret it...
>
>When an MS recording is collapsed to mono (as still happens on some
>television playback, for example), the side information is removed
>from the sound altogether. So if you had an MS recording made in a
>forest with a narrator close up in the centre and forest ambience in
>the sides, when collapsed to mono the forest ambience disappears
>altogether, totally changing the sound heard by the listener. So this
>is 'mono-compatible' in terms of not causing comb filtering when
>summed to mono, but not in terms of retaining all of the information
>that was present in the original stereo signal!
>
>In comparison, a properly configured coincident or XY pair (e.g. Rode
>NT4, AudioTechnica AT825 et al) will collapse to mono with no comb
>filtering and without losing any of the signal. This is handy in post-
>production and is also good when the signal is summed to mono during
>playback. The mixing engineer can check what it sounds like in mono
>and create a balance that works well in 5.1, stereo and mono.
>
>If an AB pair is used, converting to mono in post-production is
>simply a matter of using only one of the mic signals (unless they're
>very widely spaced apart and/or very close to the sound source, the
>two mics should sound pretty much identical with only time
>differences between them). That's not going to be much help if the
>stereo signal is being converted to mono during playback (in which
>case you have to be careful of comb filtering when placing the mics),
>but it does give the post-production people something useful to work
>with.
>
>But if you're not making recordings for film, television or
>documentary use, perhaps mono-compatibility is a non-issue. My
>personal POV is that we're living in 2008 and mono-compatibility
>ought to be something relegated to the same bin as DATs and [insert
>whatever technology you think is well past its 'use by' date]. But it
>bit me on the bum as recently as 18 months ago...
>
>- Greg Simmons
>
I'd like to steer some of the discussion back to stereo imaging
performance comparisons if I can.
Here's an outdoor, 180 degree (clock positions), high gain, 100'
localization comparison that Rich Peet and I did last winter with
three arrays:
A) MKH40/80 M-S Rig
B) 2 X AT-3203's 90 degree flush-mount hi density foam "Wedge" (half
of Rich's "Cube Mic")
C) 2 X Rode NT2000's Parallel Boundary Rig
http://www.uwm.edu/~type/audio-art-tech-gallery/mediafiles/M-S_Wedge_PB_Local_v02_Sor3_12fps.mov
There are different mics used in each array and there are some
annoying changes in background sounds that I'd like to avoid in
future comparisons, but this attempt suggests to me that the
differences and tade-offs are probably going to be pretty dramatic
and complex in diffuse field contexts. Note that all three rigs were
running at once so the impulses are identical.
The movie plays in a loop. After you get a sense of the test set-up,
it can help to close your eyes and evaluate the performances "blind."
Rob D.
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