Excellent X/Y stereo SDC cardioid mic for field use? Schoeps X/Y CLONE?

[roonsbane]

I have always done it exactly like it is pictured in your post. This works perfectly with all of the front fire schoeps mics. There is a reason why it is positioned like this. When the array is positioned above the ensemble this will make for the least amount of interference between the two mics and if you look closely you will notice the cardioid is set back to be located at the center of the MK8 capsule. Time arrival at the two capsules is as close as it's going to get. I have never used the side fire cardioid though I have used the Mk6 set on cardioid. My gut reaction without directly A-B-ing the two in cardioid is that the dedicated front fire patterns are better, certainly in omni.
Cameron

[boojum]

My experience and thinking tells me that doing it exactly as the manufacturer suggests in MS recording is the wisest way to go. After all, they did the experiments and design. They want the best possible sound from the setup for us.

I believe that when the backs, the threaded ends, of the capsules are aligned the diaphragms are also aligned. This is front address capsules only.

A quick note to Jerry at Posthorn in your fair city would verify this.

[666666]

Originally Posted by roonsbane

...you will notice the cardioid is set back to be located at the center of the MK8 capsule. Time arrival at the two capsules is as close as it's going to get...

Thanks Cameron

IF, with all these Schoeps capsules, the exact point where the sound hits the capsules is in the true "center" of the capsule "barrel", then in the picture I posted in the last post, the sound arrival points would be approximately 20mm away from each other (being as the "barrels" are 20mm in diameter).

With this in mind, if I place a side-addressed MK4V in "front" of an MK8, the distance between the actual capsule points would be the same. The only difference would be that the MK4V capsule would be in "front" of the MK8, and is thus between the MK8 and the source... but it IS the null area. I'd hope that this wouldn't make for any severe side-effects as it is not TOO different ultimately than what Schoeps shows at their site using a front-addressed cardioid for mid.

I hope that my "plan" works out ok, putting an MK4V in "front" of the MK8, and thus being able to hold the mics "upright" (so the sound enters the sides)... because this would be the ultimate Schoeps MS set-up for my needs.

I also thought about exploring the Schoeps miniature CCM compact capsules etc and could then do something like this:

Very small and compact indeed. But considering the cost of all this stuff, I prefer having the CMC6 bodies as they are just more versatile in general, at least for the type of things I do most. I think the CMC6 bodies offer a great deal of overall flexibility in a studio, utilize standard mic cables, fit into standard SDC mic clips, etc, etc, etc... as I will be using them in a recording studio as well as for field use.

[666666]

Originally Posted by boojum

My experience and thinking tells me that doing it exactly as the manufacturer suggests in MS recording is the wisest way to go. After all, they did the experiments and design. They want the best possible sound from the setup for us...

I certainly agree with this mode of thinking 100%.

But this doesn't necessarily mean that what I'm trying to do will not work as well. Schoeps has not specifically stated anywhere that doing what I'm thinking of doing is not a good idea... or if they have, I have not seen it.

I believe they show their mics in MS using a front addressed cardioid (and pointing at the source) because it's simply a more common way of arranging it. Perhaps most (or just about all) other professional recordists out there do not feel a need to be able to hold mics in an upright position, so this arrangement is not commonly considered. Though I could be wrong of course!

I'll have to poke around more and perhaps ask a knowledgeable Schoeps person. And I may never really know anyway how it will work for me until I try it first-hand. As many others have said though, I can't go wrong picking up some extra Schoeps caps anyway. The MK8 can be used regardless. And I still might wish to experiment with a pair of 4Vs in X/Y anyhow. Absolute worst case scenario, I pull out one of my front-addressed MK4s (that already reside in my current kit) and use it along with the MK8 for MS... and I'll just have to suck it up and point the mics at the source in frontal-addressed fashion.

[boojum]

You can write Schoeps directly or Jerry at Posthorn. Jerry has along history with them, has an excellent background recording and designed one of Schoeps' recording spheres. He knows his stuff. Either way will get you a definitive answer. DSatz who is on this board is also extremely knowledgeable about mics in general and Schoeps in particular.

I like to learn from others' mistakes rather than my own. Also, starting from a proven technique allows you to experiment from there rather from some unknown spot.

Good luck and let us know how it goes.


Cheers

[Matti]

This was my standard ( with 41 capsule ) when I was in the documentary bussiness years ago. The editors have to know its recorded in MS to keep the tracks paired for the sound department if there is post prod audio as should.

Matti

[aracu]

Originally Posted by 666666

Interesting. But what about the "rear" pick-up from a figure 8 in mid position? Or perhaps I am misunderstanding something? Let's say you're in a music club, and behind you is a large, noisy crowd, plus a lot of general muddy reverberation from the room / ceiling etc, wouldn't this then be picked up to a large extent by a figure 8 in mid position? And if so, you would not be able to separate it later from the subject (in front of you) that you are TRYING to record. Correct?

What you are saying makes sense, and I can't guarantee that the figure 8 capsule will create a less noisy recording in every situation. However, if you are able to test both cardioid and figure 8 in the same situation, you may find that the fig 8 will
give you a less noisy recording in a MS configuration, but especially the kind of noise produced by air conditioners,
lights etc. I say this based on testing them in a few different situations. The fig 8 rejects more from the sides and more from above and below. It could be tilted downward so as not to pick up much of the crowd.

You can also try a pair of coincident cardioids to try to isolate the source from the crowd. The stereo image will tend to clump together in the center.

[Matti]

As you understand a cardiod is a mix of 8 and omni

Matti

[richgilb]

Originally Posted by 666666

These above mentioned mics are not stereo, they have absolutely nothing to do with my question. But thanks for the thread bumps.

what are these then? Peluso CEMC6 Two Acoustically Matched Solid State Microphones

[666666]

Originally Posted by richgilb

what are these then? Peluso CEMC6 Two Acoustically Matched Solid State Microphones

These appear to be two separate "mono" microphones. I was asking about a single stereo microphone, meaning one single microphone with two individual capsules / channels built-in.

Of course you CAN use two separate mono mics together for stereo use, but that's not what I was originally interested in doing... reasons described in first post and following posts.

But thanks anyway for the recommendation.

[666666]

Ok... I wrote to Schoeps directly and received a very prompt reply, all the way from Germany... very impressive.

I will paste the reply below, but I'll just jump ahead here and mention that Schoeps suggests that my idea of placing an MK4V in "front" of an MK8 for MS use is a bad idea... due to time arrival issues.

In an earlier post I suggested that the distance between the actual diaphragms should be the same with my plan verses the way Schoeps recommends. BUT one thing I did not take into consideration, now thinking more about it... even though the diaphragms are the same distance from EACH OTHER with both plans, the diaphragms are also the same distance from the targeted SOURCE with the Schoeps arrangement, where as with my plan, the figure 8 mic will be 20mm farther away from the targeted source than the MK4V.

Here is Schoep's exact reply:

"...if you place the MK8 behind the MK4V the sound does not reach the capsules at the same time anymore as the MK8 is farer away from the sound source. As MS uses sum and difference of the capsules' signal this will lead to significant decoding errors. We do not recommend to place a MS microphone pair that way.

You could use our UMS20 stereo bar for your purposes. You can mount your microphones like on the attached picture then. This way you will reach perfect MS results..."

Ok, makes sense.

What this ultimately means is that I will not be able to do MS with a mic arrangement that allows me to hold the mics upright in a "compact", "side-addressed" manner. Oh well. BUT, I can still always use two MK4V mics "upright" for XY use.

And thinking about it further, as much as I am more excited than ever to rigorously explore MS recording, there IS one main advantage to XY:... instant gratification. If I want to check the recording quickly in the field, I can just stick some headphones into my Tascam portable CF recorder, and hear XY stereo, ready to go. If I record MS, it will be way more difficult to check anything without "decoding" it first, and I won't be able to decode out in the field... and I do not plan on adding any "decoders" in front of the recording device, etc... this is a small, portable rig that runs on batteries, I do not wish to add any extra "accessories" if not absolutely necessary.

Oh yeah, and here is the picture Schoeps sent me to exemplify the proper way to use an MK4V and MK8 together for MS use.... as you can see, not a very "compact" arrangement. I'd be much better off just using an MK8 with regular MK4 and point them at the source.

[boojum]

There are recorders which decode MS on the fly and you can monitor MS in its decoded state. The result is that you have the same control as if you were doing regular XY. One of the great beauties of ms is the degree of control you have "after the fact" in post.

And, yes, Schoeps support is excellent. They are famous for that and quality gear. Hard to beat that combo. ;o)

[richgilb]

Back to the Pelusos then? I am just waiting for a ups delivery on them right now.....

[666666]

Originally Posted by boojum

There are recorders which decode MS on the fly and you can monitor MS in its decoded state. The result is that you have the same control as if you were doing regular XY. One of the great beauties of ms is the degree of control you have "after the fact" in post....

I am indeed very excited to explore MS more thoroughly soon.

My field recorder (Tascam 2-channel HD-P2) I'm pretty sure does not have a built-in MS decoder on the headphone output. But I'll check. I don't remember ever noting such a feature on that unit, then again it does have a very large amount of features, might have missed it.

I wonder if anyone sells a super small passive MS decoder that could be plugged in between the recorder and headphones... or perhaps be fed from the main audio outs and then have a headphone output jack on it.

The more I think about it, due to this decoding issue, I could see myself potentially using XY in cases where I'm recording something for someone else (often just a favor) and just want to be able to shoot them the stereo audio file quickly, as is, right out of the recorder, without having to bring it into a mixer to decode / tweak etc. There's something to be said for being able to upload a stereo audio file from a recorder into a computer and then instantly upload to a server, all done before you even finish your first cup of coffee.

However, for things I'd be recording for my own purposes where I DO wish to have maximum tweaking control later in the studio, MS sounds like an awesome strategy. I have to question if I really need to monitor a decoded signal anyway in this case. Usually when I'm recording in a club etc, I am not wearing headphones / not monitoring on the fly anyway. So perhaps I do not even need a decoder. BUT, if there was one available, super small and inexpensive, I'd probably pick it up, just to have... I'm sure it might come in handy.

[boojum]

FWIW - you can convert XY to native MS and adjust the ratios of side and mid and then code it back to XY.

[NorseHorse]

The imaging STILL won't be the same though. The patterns of each mic overlap significantly in XY, creating a center-heavy image. The ambience is collapsed to the center, making it more difficult for the mind and ear to isolate and focus on the sound.

OP, check your PMs if you want to hear comparative samples.

[didier.brest]

Yes XY and MS are equivalent if X, Y and M are exact cardioids (1 + cosine) and M exact figure of eight (1 + sine) directivity. It result from simple trigonometry. With true mics, it may not be exact.

[Tom McC]

.. and M exact figure of eight (1 + sine)...

Sorry, but the Fig-8 polar patten is actually cosine(theta), with angle 'theta' referenced to the mic's main response axis.

With an omni = 1 and a Fig-8 = cos, a cardioid (which is omni plus Fig-8) becomes 1 + cos.

[didier.brest]

Yes, my mistake. I wrote sine because in the case of a S channel, the source direction is at 90° with respect to the mic pattern axis. So implicetely I took the source direction as a reference. Then the X and Y patterns are 1 + cosine( angle - 45°) and 1 + cosine(angle + 45°). As a brief, if angle defined for all patterns with respect to the source:

M pattern = 1 + cosine(angle)
S pattern = sine(angle)
X pattern = 1 + cosine(angle + 45°)
Y pattern = 1 + cosine(angle - 45°)

Then
M + S pattern = 1 + sqrt(2) x cosine(angle - 45°)
M - S pattern = 1 + sqrt(2) x cosine(angle + 45°)

where sqrt(2) is square root of 2 = 1.414...

Eh... I don't get what I was expecting. The M+S and M-S patterns are not exactly the X and Y pattern, although they are maximum at 45° and -45° and minimum at the opposite directions. I don't see my mistake if any.

[Tom McC]

Originally Posted by Tom McC

Sorry, but the Fig-8 polar patten is actually cosine(theta), with angle 'theta' referenced to the mic's main response axis.

Nerdy follow-up: I just realized that Didier may have intended the polar pattern equations all to be referenced to the same angle direction in real space, namely that of the forward-facing cardioid, with the Fig-8 mic in the MS array having its plus lobe pointing left. Referenced to the cardioid main axis, the Fig-8 pattern then becomes cosine(theta - 90deg) = sine(theta). But not 1 + sine.

[pkautzsch]

Originally Posted by NorseHorse

The patterns of each mic overlap significantly in XY, creating a center-heavy image. The ambience is collapsed to the center, making it more difficult for the mind and ear to isolate and focus on the sound.

You can easily increase the angle of an XY setup to decrease (!) the recording angle, ie. to widen the image. But with cardioids in XY, you'll usually pointing way past the source if your recording angle is small enough, and you'll be coloring the sound more or less depending on mic type. (For recording angles, see Image Assistant )
In MS, you have one mic pointing directly to the source, and a fig-8 condenser mic usually isn't very colored off-axis.

Originally Posted by didier.brest

Yes XY and MS are equivalent if X, Y and M are exact cardioids (1 + cosine) and M exact figure of eight (1 + sine) directivity. It result from simple trigonometry. With true mics, it may not be exact.

XY isn't exact with true mics, either. Nor is spaced pair, ORTF, or any real mic setup, for that matter. The good thing about it is that our speakers and our ears aren't exact, either.

[didier.brest]

From my previous post, it seems that even if X, Y and M are exact cardioids and S exact figure of eight, MS cannot be made exactly the same like XY.

[Tom McC]

Originally Posted by didier.brest

From my previous post, it seems that even if X, Y and M are exact cardioids and S exact figure of eight, MS cannot be made exactly the same like XY.

When you generate a "virtual" XY pair by sum & difference matrixing of an MS pair, the included angle of the virtual pair will of course vary with M/S ratio, but the polar pattern of the new directional mic also varies. If you matrix a cardioid M with a narrower Fig-8 S, it's logical to expect that the new virtual mic will have narrower pattern than the mother cardioid, because it has a tad more cosine stuff in its maths.

Only when a Fig-8 mic is used for both M and S does the X and Y polar patterns stay invariant of M/S weighting (viz. Fig-8 shape; ignoring the trivial case of two coincident omni's <g>)

Consider the case of MS using an ideal cardioid and Fig-8, with the mics having equal sensitivity and equal gain settings: Referenced to the cardioid straight-ahead angle,x, = 0 deg., the virtual mics will have the polar patterns:
L = 0.5(1 + cosx + sinx) R = 0.5(1 + cosx -sinx]

This will deliver an XY array with main axes 63.4 deg. left- and right of straight ahead, i.e. an included angle (not recording angle) of 127 deg. And their X,Y polar patterns? They will be ca. 12dB down at 90 deg. off their major axis, i.e. hypercardioid-like (a cardioid is 6dB down at 90 deg. off axis). I find it helpful and illuminating to set up a simple spreadsheet to run various scenario's of M pattern and M/S gain ratio.

[didier.brest]

Originally Posted by Tom McC

Consider the case of MS using an ideal cardioid and Fig-8, with the mics having equal sensitivity and equal gain settings: Referenced to the cardioid straight-ahead angle,x, = 0 deg., the virtual mics will have the polar patterns:
L = 0.5(1 + cosx + sinx) R = 0.5(1 + cosx -sinx]

This will deliver an XY array with main axes 63.4 deg. left- and right of straight ahead, i.e. an included angle (not recording angle) of 127 deg.

No, the main axes are at 45° left and right because
1 + cos(x) + sin(x)= 1 + cos(x - 45°) x sqrt(2), the maximum of which is for x = 45°.
Anyway my point was that this was not a cardioid pattern and we agree on that. More generally, I would state that M-S from cardioid and figure-of-eight cannot be made equivalent to some non null angle cardioid XY whatever is the mixing coefficient of M and S.
I agree than figure of eight MS can be made equivalent to any figure of eight XY.

[Tom McC]

Originally Posted by didier.brest

No, the main axes are at 45° left and right because
1 + cos(x) + sin(x)= 1 + cos(x - 45°) x sqrt(2), the maximum of which is for x = 45°.
Anyway my point was that this was not a cardioid pattern and we agree on that. More generally, I would state that M-S from cardioid and figure-of-eight cannot be made equivalent to some non null angle cardioid XY whatever is the mixing coefficient of M and S.
I agree than figure of eight MS can be made equivalent to any figure of eight XY.

Didier, we do agree on the general principle outcomes of the MS -> XY transformation, but we differ in the mathematics. Frankly, I don't understand where you are pulling this mysterious "sqrt(2)" from.

But luckily for me <g>, my results are in complete agreement with those of the illuminaries, Wes Dooley and Ron Streicher in their seminal paper (which I believe was mentioned earlier in this thread?):

"M-S Stereo: A Powerful Technique for Working in Stereo" W.L. Dooley and R.S. Streicher, J. Audio Eng. Soc, vol 30, No 10 (1982), pp 707-718.

On p 708 of that paper, they even give a general trig formula for calculating the half-included-angle of the resulting XY pairs.
Appled to our discussed example, that formula simplifies to:
angle = arctan(2) = 1.1071 radians = 63.43 deg.

regards

[didier.brest]

Just a bit of trigonometry:

cos(a+b) = cos(a)cos(b) - sin(a)sin(b)

Let put a = x and b = -45°

cos(x - 45) = cos(x)cos(45°) - sin(x)sin(-45°)

cos(45°) = sin(45°) = -sin(45°) = sqrt(2)/2

Then it comes

cos(x-45°) = (sqrt(2)/2) x (cos(x) + sin(x))

that is

cos(x) + sin(x) = sqrt(2) x cos(x - 45°)

thumbsup

[Tom McC]

Originally Posted by didier.brest

Just a bit of trigonometry:



thumbsup

Didier, we risk changing this into Geekslutz <g>.
It's late in the day to discuss your maths line by line, but let me instead return to your post #49 and make some points:

In that post you had:

a) M pattern = 1 + cosine(angle) <= agreed
b) S pattern = sine(angle) <= agreed
c) X pattern = 1 + cosine(angle + 45°) <= No. 1 + cos(angle - 45°)
d) Y pattern = 1 + cosine(angle - 45°) <= No. 1 + cos(angle - 315°) = 1 + cos(angle + 45°)

Assuming the usual convention that the angle starts at straight ahead ("North", say), increases in counterclockwise direction, and that the X mic represents the "North-West" pointing one. But, what is the point of tussling with the mapping formula for the 1 + cos cardioid patterns for the angled X and Y mics, for we have already found that a virtual mic at 45° won't be inherting a cardioid pattern, anyway?.

Look, "the proof of the pudding is in the eating thereof" <g>, so I would urge you to try the following: take equations (a) and (b) - that we all agree are OK - and compute "M + S" on a spreadsheet for a range of angle values. I would suggest displaying angle values in columns at 5 deg. intervals (thus +90, +85, 80, 75, 70....5, 0, -5, -10, -15°..etc.).

By inspection you can locate the maximum value that M+S takes. This represents the angle that the main axis of the virtual mic lies on, or in other words the half-included-angle. You'll discover that it lies between 60 and 65°, and indeed is the 63.43° as calculated by Dooley, Streicher and lil 'ol me <g>. At the same time, you could convert the obtained M+S values from voltage into dB, to get a handle on the new polar pattern.

And by then I'll have gone through your maths.

regards,

[7rojo7]

The big diference is in mono, S disappears, in xy it doesn't. You may want this.
Your M better be pretty good!
Originally M/S was used with an omni and a fig8, to me, this makes better recordings for music (if you have to use M/S) and like this you can control the lobes of the omni pickup besides synthesizing stereo.
For 'Stealth' recordings in noisy places, indeed this is where cardioid and fig8 M/S would be useful as you will need to be able to 'focus', however, you still lose the S in mono. xy can be encoded to M/S as can any stereo source, and when xy is encoded to M/S you will not lose the S. if someone is brave enough to trig it out go ahead, make my day.
I find M/S to sound like an effect, as I do Blumlein (I use blumlein for recording BKG VOX with a pair of reflective gobos at 60 deg 3 times the distance as the mic to source, I had the pleasure to record the Roches like this once, with a C24), xy may be boring but its detail is realistic (discrete), just put it in the right place.
For me M/S has worked only when it's very close to the subject, but it lacks realism, the further away it is the more mono it becomes (like any other array), with a cardioid, the proximity effect is going to make you go searching for an eq, you'll have to be far away so that you're M can pick up the whole subject, can't get too close or you lose your sides with the cardioid pickup and too far it starts to sound weak and honky and the sides also (as fig8 has a more pronounced proximity effect than cardioid) this gives you a very limited range of distance to where you can place this array, with an omni you have a larger leeway. All in all it's never been practical for me, audience mic, but ORTF works better there, SFX if you don't need to catch the Doppler effect faithfully.
I have an ATM825 and it is LR, not xy, good for OH, stereo Ac Gtr. The Schoeps looks like an LR also, the Rode is xy but not adjustable (for stealth this is good) but seem 'fragile' for stealth, great specs, I wonder how it's voiced. I would use 2 CCM4v configured like a standard side address stereo mic (C24, 424, SM2, U69, etc...), I'm sure you could figure some way to mount them sturdily. The mount for the side address M/S for the CMC bodies would work, maybe they have that for the CCM also. OMD. I have 6 CCM mics and I adore them. Line makes some interesting mics as does Josephson, I'm dying to be able to hear them.

[didier.brest]

Originally Posted by Tom McC

I would urge you to try the following: take equations (a) and (b) - that we all agree are OK - and compute "M + S" on a spreadsheet for a range of angle values. I would suggest displaying angle values in columns at 5 deg. intervals (thus +90, +85, 80, 75, 70....5, 0, -5, -10, -15°..etc.).

By inspection you can locate the maximum value that M+S takes. This represents the angle that the main axis of the virtual mic lies on, or in other words the half-included-angle. You'll discover that it lies between 60 and 65°,

If you will do this, you will find that the maximum of M+S and M-S are at -45° or +45° (or vice versa), because it's a consequence of the trigonometry relations here above.

[Tom McC]

Originally Posted by didier.brest

If you will do this, you will find that the maximum of M+S and M-S are at -45° or +45° (or vice versa), because it's a consequence of the trigonometry relations here above.

Didier, the trig relationships in your post # 56, while mathematically sound (apart from small typos), don't serve any logical purpose: Why do you even have to introduce the terms 45°, or (X - 45°) or cos(X-45°) into your formulae in the first place?.This only puts an extra layer of complexity onto the calculations. There is no justification for doing it . Indeed, by doing so, you are essentially already imposing an _assumption_ that +/- 45° angles should somehow be playing a significant role in the analysis. Small wonder then that a +/- 45° emerges from the output (though I've still to pinpoint the flaw <g>)

An M + S or M - S can most certainly have a maximum beyond 45°. For example, consider the case of MS from an omni with a Fig-8: This has a maximum signal level at 90° (i.e. yielding back-to-back side-facing cardioids). You should be able to visualize that from symmetry considerations alone. Or are you perhaps talking about maximum signal power rather than maximum voltage level?

Let's revisit the case of doing MS from a front-pointing cardioid (1 + cosX) with a plus-lobe left-pointing Fig-8 (sinX). You agree that the L-oriented virtual mic takes the pattern M + S = (1 + cosX) + sinX

Now that's a pretty lean, ascetic trig relationship. They don't come much simpler, so it's easy to compute for a range of X values. And the arctan formula gives the exact value of the virtual mics included angle. (There is no need to undertake the academic exercise of reworking the "1 + cosX +sinX" into, say, an "A + Bcos(X-C)", cardioid-like format, in order to allow a quick 'n dirty visual estimate of the mic pattern and included angle).

Have you done the (spreadsheet) calculations yet? I have, 30 years ago. Have you read the Dooley and Streicher paper?.

I think it's maybe time to wind down this theoretical sub-thread. After all, it's been only about idealized mic patterns. But I've nagged on because it had occurred to me that if folks carry the misconception that an MS from equal dosage of M-cardioid with S-Fig-8 produces hypers at +/- 45°, or, even worse, cardioids at +/- 45°, then that could be the source of the widely-circulating mantra: "MS technique gives inadequate stage width".

Tom
"Music is the greatest silent force in the world" - Lionel Richie, interview .