M/S Mic Question

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In article <37f986de.0411130740.2873113f@posting.google.com> locosoundman@netscape.net writes:

> If the mid mic were a Schoeps CMC64 and you had a choice between a U87
> and a C414B-ULS, for the side mic, which would you prefer, and why

The C414, because it's easier to mount.

I think I'd prefer a Sennheiser MKH30 though. It has a better
bi-directional pattern than either of the large diaphragm mics you
offered as a choice, it's very quiet, and it's easy to use.

> Choir, piano, harpsichord, guitar, drum OH

Understand that you don't choose an M-S configuration based on the
instrument, you choose it based on the room. In a bad room, any M-S
arrangement could give emphatically poor results on any of those
sources.



--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

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<< locosoundman@netscape.net (locosoundman) >>
<< If the mid mic were a Schoeps CMC64 and you had a choice between a U87
and a C414B-ULS, for the side mic, which would you prefer, and why, on
any or all of the following sources:

Choir, piano, harpsichord, guitar, drum OH >>

I would use mismatched mics in MS if I had a small sounding room and I
wanted it to sound bigger. Were I doing that on a small choir and drums, I
would use the U87 as the sides mic as it's smoother sounding than a 414B-ULS.
Unless the micpres were on a Mackie mixer, which is pretty unkind to U87's,
probably then the 414B would sound better on the sides. Unless it didn't sound
better of course...

Guitar and piano I would first try close stereo micing with mismatched
pairs in cardiod or figure 8 patterns, rather than distant micing in MS.

Will Miho
NY Music & TV Audio Guy
Audioist / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

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Scott Dorsey wrote:

> Neither the U87 or the C414 are going to be anything approaching the
> same response as the C414, so that objects on the edge of the sound
> field will sound different than those in the center. In both cases,
> those mikes are a lot brighter than the Schoeps, so stuff on the edge
> of the field will become brighter. My feeling is that if you have to
> use an unmatched side mike, you'd want something duller sounding than
> the mid mike, like a Beyer M130, because having the edges of the
> soundfield duller than the center seems less annoying.

(Assuming that in the second line you meant to write "the CMC 64" ...)
A figure-8 with rising high frequency response--especially if that
response is not evenly maintained at all angles of sound incidence--
will definitely skew the stereo imaging.

But the issue which I would encourage folks to think about isn't the
match or mismatch between the M and S microphones of a pair. Rather,
I see the accuracy of the figure-8 microphone's directional pattern,
and the consistency of that pattern throughout its bandwidth, as the
main things which determine its suitability for M/S use at all--of
course assuming that its noise and distortion are low enough, too.

The S microphone in an M/S pair has a very specific function: to
produce the difference information between the eventual left and right
stereo channels. The better it can perform that one function--the more
accurate its figure-8 polar pattern is, and the flatter its frequency
response is--the more freedom one then has to choose an M microphone
with whatever coloring (or lack thereof) and pattern one prefers.

Ideally, an S microphone should be chosen such that its sonic character
is not a significant factor in the eventual stereo result.

The U 87's figure-8 setting is a little bright on axis and rolls off
at the sides. It's a nice sound for a number of other uses--but of
the two microphones proposed, I'd sooner use a C 414B-ULS as the S
microphone for M/S pickup, I think.

--best regards

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Sugarite wrote:
> A small diaphram fig-8 would make much more sense, but they don't
> exist, except by using two opposing cardioid capsules, which introduces
> phase issues from the slight displacement between the two, in addition to
> the problems from the displacement between the mono and side mics...

This is an excellent solution to the problem, actually. If
you mount the two back to back cardiods one atop the other
you will largely avoid the non-coincidence problem. It's a
DIY proposition, though, because you pretty much have to use
raw capsules.

Using three identical capsules, one for the front and two
for the side and reasonably matched is pretty near optimal
for M/S IMO.

>
> Frankly I've been much happier with coincident XY wherever MS might be used.
> People complain that XY isn't always "wide" enough, but it's so easy with a
> few custom cables to isolate the side channel using the inserts and a stereo
> auxiliary, and it's even simpler with Waves Stereo Imager in the box, and
> the result is far less comprimised than a MS array IMO.

Since the coincident XY can be easily matrixed back to MS in
a DAW for width manipulation, there really isn't a hell of a
lot of difference except that it is simpler.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

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Hal Laurent <laurent@charm.net> wrote:
>"Sugarite" <nobody@home.com> wrote in message
>news:kALld.10578$14.4060@read1.cgocable.net...
>
>> A small diaphram fig-8 would make much more sense, but they don't
>> exist, except by using two opposing cardioid capsules
>
>Schoeps makes a single-diaphragm figure-8 capsule (the MK8).

This is a nontrivial thing to do. Sennheiser also does one in the MKH
line, but the RF electronics on those microphones already requires some
internal capsule equalization. Schoeps manages it without doing so, and
damned if I know how they manage it, but as far as I know nobody else has
done it.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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Why is this so difficult....
> Sugarite wrote:
> > A small diaphram fig-8 would make much more sense, but they don't
> > exist,


The following small diaphram solutions do exist....

Sennheiser MKH30 fig-8 MKH40 card or MKH50 hypercard
http://www.sennheiser.com/sennheis [...] root/02872
http://www.sennheiser.com/sennheis [...] root/02645
http://www.sennheiser.com/sennheis [...] root/03109

Schoeps also has small diaphragm figure 8..
http://www.schoeps.de/E-2004/figure-8.html
http://www.schoeps.de/E-2004/ms-stereo.html#msoutdoor

Rgds:
Eric

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Eric K. Weber wrote:
> Why is this so difficult....
>
>>Sugarite wrote:
>>
>>>A small diaphram fig-8 would make much more sense, but they don't
>>>exist,
>
> The following small diaphram solutions do exist....
>
> Sennheiser MKH30 fig-8 MKH40 card or MKH50 hypercard
> http://www.sennheiser.com/sennheis [...] root/02872
> http://www.sennheiser.com/sennheis [...] root/02645
> http://www.sennheiser.com/sennheis [...] root/03109

I would consider these much too large for the back to back
solution. The mic bodies would create signifigant near
reflections into the array that would booger up the
frequency response.

>
> Schoeps also has small diaphragm figure 8..
> http://www.schoeps.de/E-2004/figure-8.html
> http://www.schoeps.de/E-2004/ms-stereo.html#msoutdoor

Yes, top tier solution and you'll pay accordingly. I tend
to forget things that are way outside my ability to
consider. :-)


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

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>However, as the Schoeps website says about the MK8, "directional pattern
>almost completely identical at all frequencies." Every fig-8 mic can share
>the exact same description, because they're all unequal front-to-rear, which
>translates to unequal left-to-right in MS.
>

Why would that be?
If using a single diaphragm figute 8 (Schoeps, Sennheiser and Neumann) wouldn't
the response be the same front to back.

I can see that slightly off axis that the response might not be perfect at all
frequencies due to diaphragm size.

Also, most ribbon figure 8's have the same front and back frequency response
with the exception of the Royer R-121 which was designed to handle high SPL's
and this changed the response.


Richard H. Kuschel
"I canna change the law of physics."-----Scotty

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Sugarite wrote:

> [A]s the Schoeps website says about the MK8, "directional pattern
> almost completely identical at all frequencies." Every fig-8 mic
> can share the exact same description, because they're all unequal
> front-to-rear, which translates to unequal left-to-right in MS.

The degree of front/back discrepancy in figure-8 microphones varies
from design to design. For example, Royer has two basic models of
ribbon microphone: one for pop and one for classical (more or less).
The "classical" one is highly symmetrical front to back, while the
"pop" one is not so much, and the company is quite open about this.
The "classical" model also has the flatter frequency response of the
two models through the midrange and upper midrange. It would thus
be preferable all around as the "S" microphone for an M/S pair.

I have some special interest in your remarks since I'm the primary
German-to-English translator for Schoeps, and those are my words that
you're quoting. Small response discrepancies do show up between the
front and back lobes of a Schoeps figure-8. But discrepancies of that
magnitude show up when you run the same curve twice in a row without
changing or moving anything, so that should be taken into account, too.

I'm looking at the factory frequency response curves for my own MK 8
capsules, using the same pen and paper speeds that Schoeps' engineers
use for their own research, not some idealized version of the curves
for marketing purposes. (Or OK--I was looking at them a minute ago,
then I put them down because I can't type while holding them, but they
are the real curves.) No discrepancy between front and back is visible
on the chart recorder until you get above, say 3 kHz, where there are
occasional burbles of some fraction of a dB or so--up to maybe one
whole entire dB (horror of horrors!) above 9 kHz.

Given the margin of measurement uncertainty, these are effectively the
same curve to within 1 dB--and below 3 kHz they _are_ the same curve.


> It's still a moot point though, you really need spaced cardioids
> to get the time differential aspect of natural imaging.

That's the direct opposite of what most people in this field believe,
and what several decades of live recording experience tell me.

Whenever you play a recording back through loudspeakers, you get the
same arrival time differences between the listeners' ears as you would
get in the original sound field. You don't need to create arrival time
differences between channels by spacing the microphones unless you're
recording for headphone ("binaural" ) playback. Otherwise it's an option
if you like the resulting sound, but it's not any kind of necessity.

Spaced microphones pretty much lead to artificial imaging. That can
be nice in moderation, and spaced microphone techniques allow pressure
transducers to be used, which can give a very natural sound in certain
respects--but natural imaging certainly isn't one of those respects.
More often you risk getting "the piano that ate Manhattan," etc.


> Try an ORTF rig before resorting to the only mic whose description
> seems to meet your unorthodox needs.

Huh?

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In article <2vsub3F2pbcqhU2@uni-berlin.de>,
Kurt Albershardt <kurt@nv.net> wrote:
>Richard Kuschel wrote:
>>
>> most ribbon figure 8's have the same front and back frequency response
>> with the exception of the Royer R-121 which was designed to handle high SPL's
>> and this changed the response.
>
>And the AEA R84 (for the same reasons.)

Note that the 77DX has very different front and back response as well, when
in figure-8 mode.

In every case, the differing response affects the quality and location of
the null. This is a bad thing in my opinion. The null on a 74B is much
better than on a 77DX.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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David Satz wrote:

> Given the margin of measurement uncertainty, these are effectively the
> same curve to within 1 dB--and below 3 kHz they _are_ the same curve.

That _is_ symmetric for all practical purposes. But you
knew that. :-)


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Archived from groups: rec.audio.pro (More info?)

> > [A]s the Schoeps website says about the MK8, "directional pattern
> > almost completely identical at all frequencies." Every fig-8 mic
> > can share the exact same description, because they're all unequal
> > front-to-rear, which translates to unequal left-to-right in MS.
>
> The degree of front/back discrepancy in figure-8 microphones varies
> from design to design. For example, Royer has two basic models of
> ribbon microphone: one for pop and one for classical (more or less).
> The "classical" one is highly symmetrical front to back, while the
> "pop" one is not so much, and the company is quite open about this.
> The "classical" model also has the flatter frequency response of the
> two models through the midrange and upper midrange. It would thus
> be preferable all around as the "S" microphone for an M/S pair.
>
> I have some special interest in your remarks since I'm the primary
> German-to-English translator for Schoeps, and those are my words that
> you're quoting. Small response discrepancies do show up between the
> front and back lobes of a Schoeps figure-8. But discrepancies of that
> magnitude show up when you run the same curve twice in a row without
> changing or moving anything, so that should be taken into account, too.
>
> I'm looking at the factory frequency response curves for my own MK 8
> capsules, using the same pen and paper speeds that Schoeps' engineers
> use for their own research, not some idealized version of the curves
> for marketing purposes. (Or OK--I was looking at them a minute ago,
> then I put them down because I can't type while holding them, but they
> are the real curves.) No discrepancy between front and back is visible
> on the chart recorder until you get above, say 3 kHz, where there are
> occasional burbles of some fraction of a dB or so--up to maybe one
> whole entire dB (horror of horrors!) above 9 kHz.
>
> Given the margin of measurement uncertainty, these are effectively the
> same curve to within 1 dB--and below 3 kHz they _are_ the same curve.

This is leading towards a debate over whether two matched cardioids are in
fact a truer match than either side of a fig-8. I'm of the opinion that the
matched card's are a truer match, mostly because you can't as easily test
the internal bipolar matching on a mic-by-mic basis like matching two
card's. In particular, when two card's achieve a null result under
opposition, they can be trusted to be matched in both mechanics and
electronics with extreme precision. It's impossible to test both sides of a
fig-8 with that level of precision. All you can do is "read curves".

> > It's still a moot point though, you really need spaced cardioids
> > to get the time differential aspect of natural imaging.
>
> That's the direct opposite of what most people in this field believe,
> and what several decades of live recording experience tell me.
>
> Whenever you play a recording back through loudspeakers, you get the
> same arrival time differences between the listeners' ears as you would
> get in the original sound field. You don't need to create arrival time
> differences between channels by spacing the microphones unless you're
> recording for headphone ("binaural" ) playback. Otherwise it's an option
> if you like the resulting sound, but it's not any kind of necessity.

I certainly hope that's not what most people in this field believe. You do
get time differentials from the separation of loudspeakers, but it's hardly
"one size fits all". To say spaced mic techniques are only appropriate for
binaural playback is as obtuse as saying coincident mic techniques are only
good for separated loudspeaker playback.

In particular, spaced mics can offer a sense of space that coincident mics
can't, since lateral sounds, in particular room ambience, result in greater
time differentials, producing a greater sense of width without comprimising
the coverage of the center signals, which for coincident mics means sending
the center signals further off-axis or widening the stereo recording in
mix/post.

There are times to add space between mics, times to widen the angle between
coincident mics, and times to narrow the angle and widen in post. Distant
micing of acoustic instruments generally means adding space IME. When a
sound reinforcement system is involved, coincident mics are imperative,
since spacing the mics generates very unnatural correlated differentials
from the separated sound sources putting out the same signal. When you have
a broad ensemble of acoustic sources, you end up somewhere in between.

I'm somewhat surprised at your opinion. Normally I'm trying to tell tapers
not to use spaced mics for concerts with PA's...

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Bob Cain <arcane@arcanemethods.com> wrote:
>Sugarite wrote:
>> When a
>> sound reinforcement system is involved, coincident mics are imperative,
>> since spacing the mics generates very unnatural correlated differentials
>> from the separated sound sources putting out the same signal. When you have
>> a broad ensemble of acoustic sources, you end up somewhere in between.
>
>But why would one be doing stereo with sound reinforcement?
> The few times I've tried it the variation due to position
>in the audience has made it useless unless you are really
>close to center and even then it just doesn't come out right.

It depends a lot on the room. In a narrow and long room that isn't too
bright, you can do a surprisingly good job of getting a real stereo image,
even on the sides. You may need mono front fills in order to deal with
the first couple rows on the side, though.

Also, a center cluster can do an amazing job of making stereo work in a
room where it otherwise wouldn't. It won't do miracles, though.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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Great thread - thanks for all of the information everyone.

In general I go with ORTF or some near-coincident variant therof but I
like to use spaced-pair techniques on large ensembles when the room
permits, or if I am using two stereo pairs in conjunction - one to
accent something like a choir, in which case I use a coincident pair
on the accent to get a strong center and clear localisation to better
blend with the diffuse image of the spaced pair - usually a nice
effect. I prefer to use coicindent methods simply for the effect of a
narrower image with a strong center, to be able to control the width
of the image later without phase problems, or for sound that will end
up on video.

I have heard much about the supposed advantage of MS over XY because
of the ability to control stereo width after the fact, but I have
never used it due to the complications of rigging it. Usually my
recordings are done live in concert, so aesthetics are a concern, but
for a recording session coming up soon (a jazz trio), I was
considering combining a spaced pair in conjunction with a coincident
pair for drums and piano. I am considering MS because aesthetics are
not a consideration in this case. Investing in a Schoeps CMC6 MK8
combo is not out of the question, but as I have not often used MS, I
would rather utilise that chunk of my equipment budget in other ways.

I would specifically like to ask David Satz a question about the
Schoeps MK8 capsule due to his familiarity, of course anyone can
respond: I have seen the response charts of the MK8, and I recall that
the drop-off in the bass and the high end were rather severe, but I
know enough to take these charts with a grain of salt. Has it been
your experience that the "accuracy" of sound reproduction was
adversely affected by this?


Bob Cain <arcane@arcanemethods.com> wrote in message news:<cnca39024fc@enews4.newsguy.com>...
> David Satz wrote:
>
> > So in general, I favor using a supercardioid "M" microphone. If I have
> > to cover so wide an area that I can't use that narrow a pattern, then a
> > centered, coincident stereo pickup probably isn't the best idea anyway
> > (unless mono compatibility is an absolute requirement).
>
> If you think of the cardiod family M as a figure 8 summed
> with an omni and if you match the gain of the figure 8
> component with that of the side, then the sum and difference
> that do the MS -> LR encoding just create a left figure 8
> pointing at -45 and a right figure 8 pointing at +45 both
> superimposed with the omni component of the M mic. The
> ratio of that omni component to the figure 8 is what
> determines where in the cardiod spectrum the real mic and
> virtual LR mics fit (hyper, super, card, sub, hypo.)
>
> If the fig 8 sensitivities are matched between mid and side
> and the M is a true card then the +-45 degree virtual LR
> mics will be hyper cardiod because their fig 8 components
> will have sensitivities that are the sqrt(2) times that of
> the actual mics while the omni component is one times the
> omni component of the mid. Thus, going somewhat
> hypercardiod with the mid, as you suggest, makes the virtual
> LR mics even more hypercardiod.
>
> In practice, the M and S sensitivities are nowhere near as
> carefully controled if one is setting one's own relative MS
> gains and it is virtually impossible to say what virtual LR
> patterns you have. For that reason, you experiment, listen
> and tweak. :-)
>
> If you further take into consideration that these patterns
> are highly frequency dependant, even if symmetric front to
> back, then it is _very_ hard to generalize what you get from
> a coincident (intensity based) stereo configuration, MS or
> XY. That's not to say, however, that they can't sound great.
>
> One thing I have not been able to get away from with MS or
> XY is that if I have a drum kit that is a fair bit to the
> side then the image separation between the kick and cymbal
> is very highly exagerated and the cymbal can even swap
> sides. This is because of the frequency dependant patterns
> and because phase matching becomes very important at the
> higher frequencies due to the MS->LR summing.
>
> The more I study this stuff the more I come to realize that
> there really isn't a theoretical basis for stereo
> configurations that holds any water because all the premises
> of the theories are idealizations that are terribly far from
> reality. It's all hueristic in the end. Try things without
> much worrying about what is right or wrong and see what you get.
>
>
> Bob

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David Satz wrote:

> If the M microphone emphasizes certain sound components (e.g. the high
> frequencies) while the S microphone doesn't, then in the eventual L/R
> stereo output of the matrix, those components will tend to gather at
> the image's center more than the midrange sound does. The apparent
> left-right position of any given instrument or voice would thus be
> blurred. Conversely, if the S microphone boosts the highs while the
> M microphone doesn't, high frequency energy would tend to be shifted
> more toward the left and right than the midrange sound--increasingly
> so with individual voices or instruments that are already off-center.

Yes. But even if they are matched blurring will occur
because frequency response is angle dependant or inversely,
the polar plot is frequency dependant. The consequence is
that the virtual mics given by the vector sum of the real
mics have axes that move about with frequency.

> It will take me another little while to say where I don't agree; the
> main issue is the fact that most microphones (except for the best
> small-diaphragm figure-8s and certain rather noisy omnis) don't have
> the same frequency response at all angles of incidence. So all our
> "virtual microphones" have rather complex, irregular response--that's
> another reason I tend to favor a super- or hypercardioid for "M".

I hadn't read ahead. You clearly understand the point I
made above.

>
> However, I'll also point out that the analog of using a non-flat S mike
> is processing the S channel independently of the M channel--and there is
> a long tradition of doing exactly that. One of the attractions of M/S
> (whether the recording is made originally that way, or whether another
> type of X/Y recording is matrixed to M/S) is that the M and S channels
> can be equalized independently or processed in other ways independently,
> then rematrixed to L/R stereo.

You want to make sure that any such manipulation that is
frequency dependant be done with linear phase filters and
that the channel not processed always be delayed by the
group delay of the filter to keep the two channels time
coherent. Changing the relative phase of M and S outputs
also has a large effect on source placement within the image.

All of this having to do with frequency dependant polar
responses and the consequence on imaging applies as well to
the XY configuration. At one extreme, look at the
frequencies where the polar plot gets close to round and all
those frequencies will be moved to the center of the image.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

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In article <cneicv01447@enews3.newsguy.com>,
Bob Cain <arcane@arcanemethods.com> wrote:

> But why would one be doing stereo with sound reinforcement?
> The few times I've tried it the variation due to position
> in the audience has made it useless unless you are really
> close to center and even then it just doesn't come out right.
>
>
> Bob

I don't think that the poster was referring to stereo sound
reinforcement, but recording an event that had sound reinforcement as a
variable, as opposed to a straight acoustic event.


Edwin

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Edwin Hurwitz wrote:

>
> I don't think that the poster was referring to stereo sound
> reinforcement, but recording an event that had sound reinforcement as a
> variable, as opposed to a straight acoustic event.

Thank you, Edwin. Confusion resolved. I was baffled by the
responses to my question and now I know why. :-)

I've been to a few large-hall surround supported shows put
on by some local Creative Labs folks who are into that and
avante garde arts and I've tried to get binaural recordings
of them. I was utterly frustrated by the extent to which
_everything_ changes with the slightest head motion.

It's not nearly so bad if the reinforcement is mono but
still, the slightest motion from left to right can
dramatically pull the apparent source to one side or the
other. I've about given up trying to get anything live in
stereo that isn't up close and cozy.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Archived from groups: rec.audio.pro (More info?)

> > This is leading towards a debate over whether two matched cardioids
> > are in fact a truer match than either side of a fig-8. I'm of the
> > opinion that the matched card's are a truer match, mostly because you
> > can't as easily test the internal bipolar matching on a mic-by-mic
> > basis like matching two card's.
>
> May I take a closer look at this rather mysterious course of logic? If
> I didn't know better, I'd think you were saying that the ease of testing
> which you imagine in a thought experiment (!) should take precedence over
> the accuracy of competent real-world measurements.

[snip]

Reversing cardioid signals is hardly experimentation. Two card's can be
trusted as a 100% match when they produce no perceivable signal when one is
inverted against the other. That catches aspects that aren't even
understood, much less measureable. That is a far more reliable test than
any that can be applied to a fig-8, except if you had a matched pair of fig
8's that stay matched if you turn one around, something I've never heard of
happening. If you reverse one or both of the fig-8's in Blumlein format
you'll get different imaging every time. The dependence on a balanced fig-8
in MS format is equally severe.

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hank alrich wrote:

> Since there is no way in the presently known universe to put two objects
> in the same place at the same time, how can wavefronts that arrive at
> different times null? Is this a fantasy test?

Not at all, Hank. While they can't be at the same place,
they can be at the same distance by placing one atop the
other pointing in opposite directions with their diaphragms
in the same plane and with that plane passing through the
source.

Here's a pic of a MS employing three little Panasonic WM55A
cards that I made to experiment with:

http://www.arcanemethods.com/MS-Ball-Off.gif

Yes, things arriving from off the horizontal plane will have
some TOA difference so there is assymetry that way but for
the direct sound, it can be quite time coherent.

That there is a front to back distance between M and S on
axis is ameliorated by the M being in the null of the S
there. At 90 degrees the distance between M and S is the same.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

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<< While they can't be at the same place,
they can be at the same distance by placing one atop the
other pointing in opposite directions with their diaphragms
in the same plane and with that plane passing through the
source. >>

Which is great for sound arriving from a single direction, i.e. an anechoic
situation. In any desirable recording venue, obviously the distance thing again
becomes slightly approximate. In the end, everything we do is slightly
approximate anyway, so what's a few millimeters this way or that?

Scott Fraser

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ScotFraser wrote:

> In the end, everything we do is slightly
> approximate anyway, so what's a few millimeters this way or that?

Possibly quite a lot if looking for complete null with two opposite
polarity, separately housed cardioids?

--
ha

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Ty Ford wrote:

> Then there's the consideration of how the mic bodies might alter the results
> because of their obstructional presence.

For sure. Grills and bodys have very large effects above 10
kHz. That's why I made my DIY MS a front address with an
axially symmetric body behind it. It's way too blunt but
that's what I had on hand. I've spent very little time at
this point evaluating that particular iteration. I know the
stereo image is good but haven't characterized the response.

If I were to ever build a commercial version of the the 3
capsule M/S I'd be paying special experimental attention to
that factor. I'd like to do one with the array at the end
of a body shaped like an Earthworks TC30K for example. One
of these days.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Archived from groups: rec.audio.pro (More info?)

ScotFraser wrote:
> << While they can't be at the same place,
> they can be at the same distance by placing one atop the
> other pointing in opposite directions with their diaphragms
> in the same plane and with that plane passing through the
> source. >>

>
> Which is great for sound arriving from a single direction, i.e. an anechoic
> situation. In any desirable recording venue, obviously the distance thing again
> becomes slightly approximate.

Correct, but my thinking is that for the usual focus of
attention, the direct sound from what's arrayed in front and
to the sides, it will be pretty optimally captured from an
M/S relative delay standpoint and the diffuse or reverberant
sound arriving with a signifigant azimuth angle will be what
is time skewed. Since that part is naturally skewed with
strong frequency dependancy and without any kind of precise
image requirements, inaccuracy there shouldn't matter too
much. I may be wrong but I don't think the time coherence
of ambience is very important.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Archived from groups: rec.audio.pro (More info?)

Bob Cain wrote:

> If, OTOH, you are multi-tracking with MS and your source is
> always on axis and compact so that you are relying on the S
> for ambience only you won't be as sensitive to mismatch and
> the MS panning plugins like Waves' "Stereo Imager" will
> preserve the spatial coherence while rotating the image.

Thanks for the point - I get it, and hadn't considered that before.

generally I do use MS in situations where most of the direct signal is in
front of the array, with most of the sides being ambience. In that case, I
like the color of the sound I get with the U87 and Royer R121. I'm guessing
that the 87 has more top, so perhaps high end will be biased to the middle
in this setup.

I hadn't encountered the situation of instruments to the side that you're
talking about, so if (when) that situation does arise, I'll listen hard for
discrepancies such as the ones you describe.

Thanks for the education.

Kyle