ORTF details?

Discussion in 'Microphones (live or studio)' started by took-the-red-pill, Apr 29, 2005.

  1. took-the-red-pill

    took-the-red-pill Active Member

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    How picky does one have to be about the exact angle, and distance between capsules when using ORTF?

    If 'very picky,' why?

    What works best, cardioid, hypercardioid, or omni?

    Cheers
    Keith
     
  2. ghellquist

    ghellquist Member

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    May 25, 2004
    If you want to do ORTF you should probably be very picky. As it stems from a state owned radio channel, they are probably very detailed in the requirements when done by their engineers in house.

    On the other hand, if what you are trying to do is to make stereo recordings just about any setup will give you a sound. A few variations on the theme has even got their own names, one example is the so-called DIN setup.

    Any change from the ORTF setup, will give some kind of difference, which might give a better sound in a specific situation. So go ahead.

    ORTF is specified with standard cardoid mics. But you can use any kind of mic really, if you like the sound you get.

    Gunnar
     
  3. zemlin

    zemlin Well-Known Member

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    Different mics have different patterns. You may need to tweak the angle to keep from getting a hole in the middle of your stereo image.
     
  4. Midlandmorgan

    Midlandmorgan Active Member

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    Jul 21, 2002
    ORTF standards (IIRC) call for a closely matched cardiods approx 7" apart, at a 110 degree angle between capsules...)approximately the typical size of a human head...

    DIN specs at a 90 degree spread with just under 8" between capsules.

    According to things I've read (Audio in Media, Alten, and many others, precision placement is critical. Minor degree changes between capsules and slight skewing off the 0 degree line can result in phasing, imbalances, etc...

    ORTF and DIN call for cardiods...others ( Blumlein and Faulkner techniques, both VERY cool!) call for figure 8s...
     
  5. rojarosguitar

    rojarosguitar Active Member

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    There is a very cool applet you can use to visualize the effect of changing about everything in ORTF: mic distance, angle, directional characteristics...
    It is set up to ORTF proper by default, but if you start to play with it you will see how much changes you can make and you will see the stereo soundstage and angular distribution of the positions in the soundstage between the loudspeakers.

    http://www.sengpielaudio.com/Visualization-ORTF-E.htm
     
  6. paulears

    paulears Well-Known Member

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    isn't the point that the name is the standard? Coincident or or near coincident morph into spaced at some point people argue about, and how the mics work is worthy of some study. However - with ORTF, there is a standard. If you change it, then it's NOT ORTF, but something else. If you take a Blumlein technique and change the 90 degrees to 80 degrees, it's not Blumlein any longer.

    In the theatre lighting area, where I spend lots of time, people bang on about the technique invented by McCandless (an ironic name for a person who replaced candles with incandescent lighting). The trouble is that his technique is like Blumlein - 45 degrees in and 90 degrees between them, but loads of theatres simply cannot do these angles, because of the shape of the building - so lighting people argue that they don't use McCandless, because they can't. Is 50, or 40 degrees effective? yes - but it not McCandless.


    'Based on' or 'similar too' - is good enough for most of us. As few of us have the luxury of perfect environments, my own feelings are that the official techniques are invitations to experiment. I find it difficult to listen to any recording and spend any brain power on wondering exactly what the angle was, or what the spacing was.
     
  7. rojarosguitar

    rojarosguitar Active Member

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    My point in sharing the above applet was not that it is still ORTF - if you change it, it is not, there is nothing to argue about - but rather that with ORTF as starting point you can kind of better predict what is actually to be different in terms of spatial distribution on the soundstage instead of guessing.

    What is not at all covered by this kind of calculations is how actually the tonal character, the 'sound' will change. So far I fully agree with the last post.
     
  8. cyrano

    cyrano Active Member

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    ORTF, NOS, RAI, Olson and a few others are all variations on the same theme.

    RAI = Italian broadcast
    NOS = Dutch broadcast
    ORTF = French broadcast

    They all stem from DIN (Deutsche Industrie Norm) and are time based stereo techniques. XY might look like DIN with zero spacing at an angle of 90°, but it's intensity based.

    There's even one for Korean school radio, IIRC :D

    Which means you're free to experiment with spacing and inclination. And I have no idea why the French won this war :D
     
  9. rojarosguitar

    rojarosguitar Active Member

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    I think an attempt to an answer can be found in the book by Bruce Bartlett on Stereo Recording Techniques. ORTF seems to combine the most positive qualities one could look for in a stereo recording according to listening tests.

    But: which technique or a variation on it is the most suitable really depends on what one wants to achieve...
     
  10. BusterMudd

    BusterMudd Active Member

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    As others have intimated, the "official" (named) techniques are starting points. If you have no idea how/where to start, resorting to a technique with very explicit parameters allows you to continue with a system that at the very least you can be assured will work.

    But I have never brought a protractor into a recording studio or concert hall, and the few times I've ever whipped out a tape measure it was not to measure the distance between two near-coincident capsules, so in strictest semantic terms I have no idea whether I have ever literally employed an ORTF (or NOS, or RAI) array.
     
  11. rojarosguitar

    rojarosguitar Active Member

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    I have cardboard templates for most of the standard near coincident arrays; but I never stuck with any of them in any strict sense, because departures from there worked better for the situations I was in.
    But I have never recorded large orchestras which is the scenario most of the 'official' arrays have been developed for.
     
  12. cyrano

    cyrano Active Member

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    I think it has a lot to do with the venues they recorded in. In France and Italy, the venues were somewhat larger than in Holland, fi.

    The rest is just having a standard for all recording technicians within an organisation to adhere to. Don't forget that in these days classical venues were often recorded by more than one person. You'd want to avoid differences between recordings.

    And all of it was based on research by the BBC. They developed standards too, but so stringent that their colleagues around Europe felt they needed a local standard.
     

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