Topic: how close is too close for ORTF?

[rockthing]

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

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

3 great posts in just one page of a thread. A great way to start my morning with a few heaping spoonfuls of recording knowledge. I'll need to set aside some extra time to check into that Williams pdf.
Thank you.

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

[boojum]

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!

Brian, post away.  I do my omni work with the DPA mic bar which came with the 3506 kit and will be adapting it for work with the Schoeps cards, too.  I think Williams has done the leg work for us lesser mortals.  Did you build the "Crocodile"?

Cheers

[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.

Looks like its just a longer version of the STC-g ortf bar and the model# is STC-W.Its listed in the new retail price list for $155 same price as the STC-g......."Special version of STCg for (2) MK21 capsules with active cables or (2) CCM21"

regards,
Jim