M-S with an Omni?

[Tommy-boy]

Maybe this is a silly question, but here goes. Has anybody tried using an M-S configuration with an omni as the mid? How did this impact the stereo image when compared to using a cardiod as the mid? Does the fact that the omni pattern also covers the fig-8 pattern create a build up of sound at the L/R edges creating a hole in the middle?

-Tom

[boojum]

MS with omni is not uncommon. I have played with it a bit now that I have a mic which allows this. You will get more room sound/ambiance.

[superwack]

Actually, I kinda of think MID-SIDE is "supposed" to be an omni + a figure 8 (but obviously you can use cardioid or figure 8 as well)... so, yes!

[John Willett]

Originally Posted by superwack

Actually, I kinda of think MID-SIDE is "supposed" to be an omni + a figure 8 (but obviously you can use cardioid or figure 8 as well)... so, yes!

I think the first MS was two fig.8s - Blumlein used this.


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[richgilb]

Will this not result in less stereo-like separation when splitting the fig 8 signal into 2 channels?

[John Willett]

Originally Posted by richgilb

Will this not result in less stereo-like separation when splitting the fig 8 signal into 2 channels?

Two fig.8s in MS is exactly the same as Blumlein XY when equal in level.

But, uniquely, you can widen or narrow the image without changing the polar-pattern of the resultant left and right patterns.

[timlloyd]

Originally Posted by John Willett

Two fig.8s in MS is exactly the same as Blumlein XY when equal in level.

But you would want the focal point on-axis for MS and 45degrees off-axis for xy.

[JEGG]

Originally Posted by Tommy-boy

Maybe this is a silly question, but here goes. Has anybody tried using an M-S configuration with an omni as the mid? How did this impact the stereo image when compared to using a cardiod as the mid? Does the fact that the omni pattern also covers the fig-8 pattern create a build up of sound at the L/R edges creating a hole in the middle?

-Tom

I use MS with omni very frequently, and have for many years. It's nice for almost anything if the room supports it, very full and big sound. 'Nothing esoteric or strange here.

It can rescue of very bizarre placements of chorus and/or orchestra that are dicated by the physical attributes of some buildings.

I'm completely lost with regard to your last question.

Anyway, common practice, no worries.

With this MS arrangement, you're using the two "pure" microphone types: omni, and 8. Assuming both your omni and 8 are "real."

[Torea]

Someone posted this article on the Decca Tree. It has quite a bit on M-S and the different patterns. Sorry, I forgot where I found it, but I think it was in the Remote forums, sometime in the last few days.

Surround_Sound_Decca_Tree-urtext.pdf

[panatrope]

An M-S pair comprising omni and fig-8 in equal ratio ends up as back-to-back cardioids facing L and R*. Less of the fig -8 can give you varying degrees of fat mono ...

(*Look up the Western Electric 639A - an early "directional" mic which used separate omni dynamic and and ribbon elements combined to produce a cardioid pattern.)

[leddy]

I've made a few recordings with omni MS.

It's not as spacious as other methods IMO, but it can be useful.

[JEGG]

Originally Posted by panatrope

An M-S pair comprising omni and fig-8 in equal ratio ends up as back-to-back cardioids facing L and R*. Less of the fig -8 can give you varying degrees of fat mono ...

True, but that factoid belies the real world result-which is quite a different animal from a pair of cardioids!

Cardioid, of course, is the most compromised mic design.

Figure 8 and omni are the two uncompromised designs.

With omni and 8, one has the strengths of each.

Omni with ratios of S<M are not mono when the result is stereo, right? The side mic would have to be at a level where it is contributing no L/R information. If mono is what is wanted, why put up to mic's? The 8 makes mono no fatter at any ratio. (Think of it-an 8 can only produce the opposite effect.)

Generally I use omni mid mixes where M=S or S is just a tiny bit less than M. There are occasions where a bit S>M works, as long as no problems occur with where the end product is going. Engineers at classical stations start getting concerned with event recordings employing higher ratios of S/M, but they'd not object to it on a commercial CD (which happens often) because they're never looked at that way!

If you want two cardioids with adjustable angle, look at the Schoeps product. A very nice sounding and well bit rig. With very good capsules. Other "compact microphones" like Schoeps, DPA, and the new Sennheisers are easier (than traditional mic bodies) to mount if this is wanted.

To get a better feel of varying ratios of M and S with *all* patterns for mid, consult a chart (actually, a bunch of polar charts) published by Sennheiser some years ago which offers a *visual* comparison. It's the only visually oriented chart for this information that I've seen.

IOW, if you wanted to *see* the recording angle of a particular M/S ratio for a cardioid and 8, and then *see* the same recording angle produced with an 8 and a hypercardioid, one can see that along with the corresponding ratios for the other set of mic's. As importantly, one can *see* the out of phase/polarity areas as well. Including S>M ratios for omni.

[OzGizmo]

Here is a link to a graphical display of various stereo mic techniques, change the mic types, and other parameters... well worth a play.

EBS Array XY 90° degrees Base 25 cm - Visualization of the Stereo Microphone System - Recording angle Time of arrical difference Level difference - sengpielaudio Sengpiel Berlin

[John Willett]

Originally Posted by timlloyd

But you would want the focal point on-axis for MS and 45degrees off-axis for xy.

Yes, exactly.

Two fig.8s in MS matrix out to a Blumlein pair - as I said.

If you alter the levels you can "steer" the matrixed pair closer or wider and the resulting polar-pattern does not change as you do this.

[roonsbane]

I use omni as the mid as well. I also sometimes use wide cardioid and my SF24 (stereo figure of 8) as the mid in M/S instead. I love the way these image. I hear it as emphasizing a solid middle rather than throwing folks at 11:00 and 1:00 a bit to the outsides. Of course with omni you also benefit from an extra octave in the low end that you won't get with two cards. I do love M/S by itself on solo classical guitar or lute. On the other hand, I usually don't use it by itself on ensembles, but instead along with flanks. Actually, I almost never use cardioid as the mid. Have fun with it!
Cameron

[_Morph_]

Mid-Side with an omnidirectional Middle microphone is a great way to record group vocals. I've done this a few times and, with proper acoustics, it's quite effective for recording every single person AND allowing to widen or squeeze the stereo effect after the recording has taken place.

It's perfectly mono-compatible - the omnidirectional microphone ensures that everyone is heard - and allows the engineer to adjust how much will be heard from the sides. Particularly effective in three part vocals: keep the main vocals in the fig-8 nulls and the other voices in the fig-8 ends. This way it's possible to balance the voices during mixing.

[Tom McC]

A wry, historical note: In his 1984 book "Musikaufnahmen", handling all facets of recording technology and techniques (including his own JD baby), Jürg Jecklin devoted an end chapter to a detailed description of the mic layouts deployed in a series of real concert events. These concerts covered all genres from solo piano to large symphonic works, and were generally multimiked.

The main pair listed in 16 of his 28 examples, was an omni-MS array (Neumann KM83 / KM88), with his JD system (KM83) only listed as main in 7 cases :-)

Many of the concerts, however, did concern Swiss Radio productions, so broadcast compatibility considerations might have influenced the choice of main pair.
　

[aracu]

I find ms with omni to be too "mono-ish" if placed in front of an
ensemble, but in unusual situations where the array can be placed in
the middle of an ensemble, it can produce a very nice stereo image.

[Yannick]

MS with omni results in more ambient pickup. To get the stereo image as wide as with a cardioid with same output, you have to add more S signal.

But there is a big difference that is often unmentioned, when changing the M mic:

the playback of the diffuse reverb is totally different !
With M=omni there are almost no out of phase cues in the LR mix, so the natural reverb is correlated and placed entirely between the loudspeakers.
With M=cardioid quite a big amount of reverb is recorded by the back/top of the stereo pair, which results in a reasonable amount of uncorrelated reverb material, which is played back outside of the speakers, which can actually result in a more spacious image, more of a being in the room impression.

[Corran]

Interesting, I need to put but an omni and cardioid capsule up sometime to test the real difference. I don't find myself using MS as much as I used to but I usually liked the results with an omni + fig8 than cardioid.

[panatrope]

"Fat mono" is a term I learned in early "coarse broadcasting" where a mono mix from the PA was combined with a stereo ambience pair. This was mainly for my own edification as the resulting recording was broadcast in mono, anyway, but it was surprisingly effective!

Of course, as a compromise between omni and cardioid, one can use a "wide cardioid" such as the Schoeps MK21 as the 'M'. Better ambience but more sensitive to annoying side-wall issues. A good stereo spotter combination on the right occasion.

[Remoteness]

That's funny because that's what I call my mixes when I listen to them in mono.

My stereo mixes usually sound best in mono.
It's what I'm going for when mixing...

Meaning, if your 5.1 mix sounds great in (downmixed) stereo and that sounds best in mono, you really got something special going on.

[panatrope]

It was also used recently where, due to a faulty cable, a stereo recording of a quartet in a chapel-like acoustic ended up effectively as a mono file. The performance was too good to throw away, so a closely matching reverb was found, added judiciously to the mono recording - fat (reverberant) mono, good enough for FM (where 90% of the listeners don't listen in a situation where stereo can be appreciated anyway).

As I said, "coarse broadcasting"!

[Marik]

Originally Posted by Tommy-boy

Maybe this is a silly question, but here goes. Has anybody tried using an M-S configuration with an omni as the mid? How did this impact the stereo image when compared to using a cardiod as the mid? Does the fact that the omni pattern also covers the fig-8 pattern create a build up of sound at the L/R edges creating a hole in the middle?

-Tom

Hello Tom,

In MS every pattern used for the mid after matrixing has its mathematical stereo analog. For cardioid it is XY, for fig8--Blumlein, for omni it is binaural. You can use it as a guide.

Hope it helps.

Best, M

[Jimbo]

I tracked a studio grand with an Avenson STO2 (omni) as mid, and a 414 xlii as side.

It sounded good and was pretty effortless.

[leddy]

Originally Posted by Marik

Hello Tom,

In MS every pattern used for the mid after matrixing has its mathematical stereo analog. For cardioid it is XY,

Though MS with a cardioid mid = XY hypers.

Originally Posted by Marik

for omni it is binaural.

How does this work? It is certainly my experience that omni MS sounds better in headhones, but I've never heard this explained this way.

[Roland]

Originally Posted by leddy

Though MS with a cardioid mid = XY hypers.



How does this work? It is certainly my experience that omni MS sounds better in headhones, but I've never heard this explained this way.

Although MS "technically", produces the equivalent of Cardioid XY, Blumlein, hypercardioid, etc, it must also be remembered that the end result of MS techniques do not sound the same as if these techniques were employed.

The key for me is that the side mic is exactly that, addressing the side. In my view this leads to better extended frequency pick up of the off axis sound (I'm talking about room reflections and ambience) which can lead to a pleasing sense of the space that is being used to perform in. Even with really good Omni mics, for example DPA 4006's the off axis response is considerably worse than on axis.

[loujudson]

Originally Posted by panatrope

As I said, "coarse broadcasting"!

!!! Did you learn this in a Broadcasting Coarse? '-)

[Marik]

Originally Posted by leddy

Though MS with a cardioid mid = XY hypers.

In case you use hyper cardioid for the mid...

Originally Posted by leddy

How does this work? It is certainly my experience that omni MS sounds better in headhones, but I've never heard this explained this way.

It is just a simple mathematical summing/subtraction of different patterns.

Originally Posted by Roland

Although MS "technically", produces the equivalent of Cardioid XY, Blumlein, hypercardioid, etc, it must also be remembered that the end result of MS techniques do not sound the same as if these techniques were employed.

The key for me is that the side mic is exactly that, addressing the side. In my view this leads to better extended frequency pick up of the off axis sound (I'm talking about room reflections and ambience) which can lead to a pleasing sense of the space that is being used to perform in. Even with really good Omni mics, for example DPA 4006's the off axis response is considerably worse than on axis.

Indeed, they do sound different and you are correct, this is due to the off axis response. While the DPA 4006 is a wonderful mic, the differences will be more prominent than mics with 12mm and smaller capsules (like 4004--4007, or mics using 1/2" measuring capsules, which I greatly prefer).

Best, M

[Tom McC]

Originally Posted by Marik

In case you use hyper cardioid for the mid...

Sorry, but that's incorrect: cardioid + Fig8 does approximate to hypers at ca. 130°.

The dB calculations of mic polar patterns ensuing from MS -> XY transformations has been pounded to death in earlier Gearslutz threads, e.g.:

(#77)
Excellent X/Y stereo SDC cardioid mic for field use? Schoeps X/Y CLONE?

(#72)
M-S mic technique--the lazy man's lazy way