Topic: how close is too close for ORTF?

[trajhip2000]

I'm trying to emphasize the center/drums for onstage recording, just wondering whether it's possible to get a "hole in the center" effect by setting up too close?

Steve

[goodcooker]

if the drummer is centered use X-Y. Stagelip subcards in X-Y ~110 degrees worked out well for me with no hole in the center (running Peluso subcards).

[BC]

I'm trying to emphasize the center/drums for onstage recording, just wondering whether it's possible to get a "hole in the center" effect by setting up too close?

Steve

I assume you are going to be using cardioids? The "hole in center" effect will be strongly dependent on the polar pattern. I have not heard a "hole in center" problem on stage tapes with near-coincident patterns such as ORTF, but what I HAVE heard sometimes is excessive L/R stereo separation between the instruments (for my tastes, of course YMMV). For this reason I personally like to run XY on stage with my cardioid mics since it narrows the soundstage/stereo separation a bit and to my ears has a more natural perspective on playback. I do think that the stereo separation of ORTF is more true to the original sound and separation with respect to the mic location, but on playback, I personally do not like to feel like I am listening to the concert "on stage". I guess it depends on what type of playback perspective you find appealing, maybe try it both ways, coincident and near-coincident, and see what you like.

 

[DSatz]

Answer #1: ORTF is too close if it sounds closer than it's generally comfortable to listen to. You don't usually want "the hi-hat that ate Manhattan" unless you're doing the sound track for a horror film.

Answer #2: ORTF is too close when the total angle of the sound sources (as "seen" from your microphones) extends beyond an arc of around 100 degrees (50 degrees either way from center). Thus the stereo coverage area for an ORTF pickup is a little narrower than the angle defined by the main axes of the two cardioids.

If you put the mikes so close to the sound sources that there are sources at (or beyond) where the axes of the microphones are pointing, you're going to get an odd effect: All the sources to the extreme left and right will sound as if they are coming from your left or right loudspeakers themselves. That undermines the whole illusion of a stereophonic pickup--you don't want listeners to be able to identify the loudspeaker positions by ear; you want the stereo image to extend across the space between the loudspeakers.

--best regards

[BC]

Answer #2: ORTF is too close when the total angle of the sound sources (as "seen" from your microphones) extends beyond an arc of around 100 degrees (50 degrees either way from center). Thus the stereo coverage area for an ORTF pickup is a little narrower than the angle defined by the main axes of the two cardioids.

--best regards

Sounds like a good rule of thumb.

[Tim]

Answer #1: ORTF is too close if it sounds closer than it's generally comfortable to listen to. You don't usually want "the hi-hat that ate Manhattan" unless you're doing the sound track for a horror film.

Answer #2: ORTF is too close when the total angle of the sound sources (as "seen" from your microphones) extends beyond an arc of around 100 degrees (50 degrees either way from center). Thus the stereo coverage area for an ORTF pickup is a little narrower than the angle defined by the main axes of the two cardioids.

If you put the mikes so close to the sound sources that there are sources at (or beyond) where the axes of the microphones are pointing, you're going to get an odd effect: All the sources to the extreme left and right will sound as if they are coming from your left or right loudspeakers themselves. That undermines the whole illusion of a stereophonic pickup--you don't want listeners to be able to identify the loudspeaker positions by ear; you want the stereo image to extend across the space between the loudspeakers.

--best regards

great post

[trajhip2000]

Thanks much for the replies. I am using cards, and have also been finding that the outside instruments do tend to sound a little wide. I'm not generally a big fan of XY since it does tend to squeeze things towards the center and also sounds a little closed in to me compared to ORTF, but in this situation I agree that it looks like a good option. The suggestion of using subcards is an interesting one, I do have the MK21s and will give that a try - after I run with the cards to see how that sounds first.

Steve

[Tim]

try x/y with a wider angle, like 100* or 110*

[DSatz]

trajhip, cardioids aren't usually an ideal choice for X/Y recording and vice versa, for exactly the reason you noted. A cardioid pattern is like the sum of an omni plus a figure-8; thus when you put two cardioids in the same location, at least half their "stereo" output will be mono ("coincident omnis") from the get-go, regardless of what angle you set between the capsules--even back-to-back!

For commonly-used angles between the axes, such as 90 degrees (bah, ptui, grrr, arrgh) the directivity of the cardioid pattern is so relatively weak that for much of the overlap area, the two capsules have approximately equal sensitivity. That's what causes the crowding that you've observed of the apparent sound sources toward the center in playback--again, the two mikes are picking up pretty much the same stuff so it comes out in or near the center of the stereo image. That's a form of angular distortion, which coincident cardioids give you rather a lot of.

In addition, a coincident pair of cardioids picks up all diffuse sound and portrays it as coming from the center line between the two loudspeakers--an odd effect indeed. This is lessened if you use a pattern such as supercardioid, hypercardioid or figure-8 instead, since the rear lobes of those patterns pick up diffuse sound in inverse polarity. You also get less angular distortion in the image of the direct sound.

So I strongly recommend supercardioids for the majority of coincident setups, or ORTF if you want to use cardioids. With your MK 21 capsules (Schoeps wide cardioids) you could try 25 cm spacing and the familiar 110-degree included angle; this will also give you a slightly wider pickup area than ORTF does. Schoeps actually offers a stereo bar for exactly that configuration. It isn't listed in their catalog--not even in the new Catalog 6 that's coming out shortly--but it is available through their dealers and distributors on request.

--best regards

[it-goes-to-eleven]

Sometimes the performers are setup too wide to capture within the mic angle in the space available.  Having a playback system that can image decently outside the speakers helps.

There are a lot of cases where I prefer the soundstage depth of ortf cards over mk21's. Or so my ears say.

[jhfinn]

Schoeps actually offers a stereo bar for exactly that configuration. It isn't listed in their catalog--not even in the new Catalog 6 that's coming out shortly--but it is available through their dealers and distributors on request.

--best regards

Is this stereo bar similar to the STCg or more like the UMS20?
Would you know the model#?

thanks in advance.
Jim

[boojum]

I have had great success with the Williams techniques for spacing and angling omni's, cards, hypo-cards and hyper-cards.  You can download a paper which sums it up nicely and supplies the graphs needed for the spacings and angles.  It takes the guesswork out.  You can fine tune your setup in one more step if needed.  But for on-the-fly this cannot be beat, IMO.

http://www.rycote.com/assets/documents/technical_files/The%20Stereophonic%20Zoom.pdf

[Doc]

Have you considered M/S ? I was converted by Moke and friends last and have been using it ever since.

[Brian Skalinder]

I have had great success with the Williams techniques

I've really enjoyed applying my learning from the Stereophonic Zoom (and with which I continue to experiment).  In order to increase my options beyond the limited spacing of the Vark bar, I've combined a pair of KM235 T-bars so I have the option of up to a ~40cm spread (though I typically use the Vark bar for 0 - ~20cm).  It's basically 2 x KM235 bars + a jam nut + a Bogen Rapidapter / thread adapter.  Cheap, compact way to achieve wider spacing, especially if one already has a KM235 bar (as I did).  I'll post pics if people are interested.  The longer bar is great for situations in which I need a smallish SRA, allowing me to increase spacing and reduce included angle in order to minimize angular distortion and reverberation.  Fun stuff!

[boojum]

^^^^ Great to see that someone here is using this technique.  Williams is not pulling it out of his ass.  He has actually tested mics against various sound stage breadths to get his figures.  The result is that he eliminates the guesswork ("Well, I always use NOS" or "I find DINa to be superior." "X-Y works for me" or "M-S covers it best." etc) and developed rules that tell us how it works.  We are dealing with physics here.  There have to be rules.  I bought his book from Jerry at Posthorn and carry it with me.  It is my security blanket as I have the figures stored in my PalmPilot that I carry with me, too. 

I find that using Williams techniques has raised the successes in my recording.  And that's the point.

Cheers