MS mics placement

[Toobme]

Is this mic pair noisy on its own?
ie the S mic double capsule by itself and the M mic by itself - maybe a fault in the electronics of one.?

Not on their own, but using as MS i’m noticing a touch more noise or maybe I mean graininess.
This is on quiet sources like solo classical guitar, or harp, or ambient/nature recordings.
On those, noise is exposed.
There, I’ve noticed I’ve preferred the AB pair of omnis, same mic bodies.
It’s not a fair comparison, though, and should be disregarded.

BUT I will say I’ve never had the results I really wanted from MS, but this may be because I prefer the sound of 2 spaced omnis over any coincident setup (excluding ambisonics). It could be me, my preference, or it could be genre-centric with most of my work being classical stuff.
Since one may not want to be that limiting to their craft, I usually roll with 2+ setups on a bar - like ORTF with an AB omni on the bar, or the addition of spots/flanks/outriggers to the main pair.

Like without the omnis, or at least one in the picture, I feel the absence of low freq and it’s in that way more pleasing to listen back to the recording with an omni(s). Not always, but for example, as was mentioned above - the organ; I gotta grab the lows on that, so the directional setups on their own never cut it, compared with the AB.

But those Oktavas aren’t noisy at all, but it’s a subjective thing for me - they just seem to feel grittier in MS or XY than in AB and that’s what I was meaning by noise.
They’re not quite like my Schoeps, but they make it into most sessions. The MS I’m just using for docs where it’s simple and sufficient.

Anyway, thanks for this cool thread!!

 

[RoadrunnerOZ]

The further the M/S are from the source, the narrower the stereo field and consequently the more side reflections from walls - this can lead to a perception of confused reflected sounds affecting the primary source and can also result in phase cancellations with a loss of performance. I’ve found for me this array only really works with fairly tight grouping around the mics.
With X/Y the further from the source, the less the centre is apparent and the bottom ends drops off, then you start having more reflected sound causing phase issues.

 

[Toobme]

This is a good read for anyone into recording, which you prolly came across already: https://mymic.rycote.com/uploadresources/images/The_Stereophonic_Zoom.pdf

 

[k brown]

I would imagine the grit you hear with the Oktava MS setup is HF combing due to the considerable distance between the capsules in the fig 8 head. Though Sony MS mics also use back-to-back cards for the fig 8, they are much closer together.

 

[Bert37]

There is one thing that most people disregard: Figure 8 ribbon microphones are velocity transducers. Omni and cardioid condensers are (mostly) pressure transducers. Thus, when you place a mix of these microphones as close as possible, you get a phase difference of 90 deg. Therefore a MS mix of ribbon and condesner will not work, as there is no correct sum and difference processing !

 

[kingkorg]

There is one thing that most people disregard: Figure 8 ribbon microphones are velocity transducers. Omni and cardioid condensers are (mostly) pressure transducers. Thus, when you place a mix of these microphones as close as possible, you get a phase difference of 90 deg. Therefore a MS mix of ribbon and condesner will not work, as there is no correct sum and difference processing !

Could you elaborate some more on this, seems interesting, but i don't get it.

 

[k brown]

Could you elaborate some more on this, seems interesting, but i don't get it.

A lot of people do this, and find it works quite well.

 

[zamproject]

but i don't get it.

Me neither ?!?
Maybe statement related to EM field for -dynamic- mic ?
But IIRC only the fields or vectors point at 90° in space, not the energies which are in sync in this case?

 

[Murdock]

Maybe he has the orientation in mind? That the "positive" lobe/side of the figure 8 mic should be pointing left when viewed from behind the array.
But that is also true for condenser figure 8 mics.

 

[emrr]

There is one thing that most people disregard: Figure 8 ribbon microphones are velocity transducers. Omni and cardioid condensers are (mostly) pressure transducers. Thus, when you place a mix of these microphones as close as possible, you get a phase difference of 90 deg. Therefore a MS mix of ribbon and condesner will not work, as there is no correct sum and difference processing !

There's a thread at Gearspace about it, some knowledgable people get into it.

 

[abbey road d enfer]

There's a thread at Gearspace about it, some knowledgable people get into it.

Do you have a link?

 

[abbey road d enfer]

There is one thing that most people disregard: Figure 8 ribbon microphones are velocity transducers. Omni and cardioid condensers are (mostly) pressure transducers.

This is a quite extraordinary claim. Actually, ALL figure-8 mics are velocity transducers, whatever the technology. Omni are strictly pressure transducers. Cardioids of all variations are pressure-gradient transducers.

Thus, when you place a mix of these microphones as close as possible, you get a phase difference of 90 deg.

I'd like a demonsration of this ASSertion.

Therefore a MS mix of ribbon and condesner will not work, as there is no correct sum and difference processing !

Demonstration of how a wrong analysis leads to a wrong conclusion.

 

[Bert37]

It is exactly the other way around. When I checked my own built ribbon prototypes against condensers to define the correct phasing I found this differene of 90 deg. even at moderate frequencies!
A pressure sensitive transducer provides maximum amplitude at the peak of sine soundwave --> maximum pressure. A veloctity transducer provides maximum amplitude at the stepest part of the sine wave --> maximum velocity. These are 90 deg. apart.

 

[abbey road d enfer]

These are 90 deg. apart.

Who said that two soundwaves with a 90° difference summed together result in a non-valid signal?

 

[emrr]

Do you have a link?

https://gearspace.com/board/geekzon...-pressure-velocity-sensitive-microphones.html

 

[emrr]

I have a fairly deep selection of mic types that could be used for MS. Ribbons, LDC’s, SDC’s. My Sennheiser MKH30 paired with MKH20/30/40 hands down have the best imaging results. Good ribbons, second best. LDC’s definitely the worst.


Building a horizontal B format array with (2) MKH30’s and a 20 delivers a better result than a couple low end ambisonic mics I’ve tried.

 

[molke]

Actually, ALL figure-8 mics are velocity transducers, whatever the technology. Omni are strictly pressure transducers. Cardioids of all variations are pressure-gradient transducers.

Aren’t the usual studio figure 8 microphones still (pure) pressure gradient transducers? I have a German book here (“Handbuch der Audiotechnik” with a chapter on microphones by Martin Schneider), which claims that, strictly speaking, only very special types of microphones react directly to velocity. Pressure gradient is proportional to velocity, so the distinction might be irrelevant. Cardioids would then be part pressure gradient, part pressure transducer.

 

[zamproject]

Who said that two soundwaves with a 90° difference summed together result in a non-valid signal?

I agree ?!?
In this case there is no time delay, the wavefront produce the same signal at output, this is coherent signal,
it's just signals amplitude that differs at defined time ?
To me it's -pure- phase, so theoretically the sum get +3dB instead of +6 ?

 

[Philbo King]

The 90 deg phase shift this is interesting. I plan to do some testing on this once I return home.

 

[abbey road d enfer]

Aren’t the usual studio figure 8 microphones still (pure) pressure gradient transducers?

Most often they are not, "pure" that is. Particularly condensers, most of them are fig-8 by virtue of cancelling their pressure component.

I have a German book here (“Handbuch der Audiotechnik” with a chapter on microphones by Martin Schneider), which claims that, strictly speaking, only very special types of microphones react directly to velocity.

It is true. A "pure" native velocity mic requires a diaphragm exposed symmetrically to soundwaves. Ribbons are naturally in this case, condensers are challenging because the "backplate" must be acoustically transparent.

Pressure gradient is proportional to velocity, so the distinction might be irrelevant.

Correct.

Cardioids would then be part pressure gradient, part pressure transducer.

They are indeed.