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Pseudo ORTF question?

Discussion in 'Recording' started by took-the-red-pill, Jul 21, 2005.

  1. took-the-red-pill

    took-the-red-pill Active Member

    Hi guys
    There is actually a question at the end for those who don't get too bored

    I bought one of those little bars that allows you to put two mics on one stand. I happen to have HM-1's, so the way the holders are I can place the mics anywhere from 3" apart to 10" apart, which is cool. I place mine about 7" apart, like an ORTF array.

    To record stereo acoustic guitar:

    1-I place my array in front of the 14th fret of my guitar at about 12-14" out.

    2-Then I rotate the whole thing 90° so one is pointing up, and the other down(otherwise, one is pointing at the sound hole and gets really boomy, and the other is pointing up the strings and picks up all the squeaks.)

    4- Now we start breaking rules, I point my mics 90° INWARD instead of outward, so they're pointing more or less at that 14th fret.(I figure I want to record the guitar, not the player breathing in one ear)

    5- I then make sure the bar that holds the array in place is parallel to the top of the guitar, so the mics are the same distance from it, to minimise phase problems.(or is it "comb filtering"...you konw what i mean)

    So doing this I get an easily created and reproduced stereo recording where both mics are pointed at the sweet spot on the guitar. I have tried summing to mono but don't hear any bad phase issues so far. All I hear are good things, but remember, mine are not professional ears.

    My question is: Is there something I'm missing? Is there some reason why this might be a generally bad idea and should be avoided? Nobody wants to be the guy famous for working to perfect a completely flawed technique, right? .:shock:

    Thanks gents. I value your opinions.

    I was next going to try this ORTF thing, with the mics pointed inward, on vocal. I figure that at best I could get a good stereo recording. At worst, if I end up with horrendous phase issues, or a plosive in the perfect take, I can always go back down to one channel, and since the two mics are 7" apart, it means that if one side got nailed with a plosive, the other will be free and clear...That's my thinking anyway.

    Any opinions on that one?

    Cheers
    Keith
     
  2. TornadoTed

    TornadoTed Guest

    If you want to have a go using ORTF then have the mics at 110 degrees facing outwards, 7" apart. In my experience you need the array to be AT LEAST 18" from the guitar which will counteract the booming sound hole problem. The room you record in makes or breaks this technique because the distance involved brings in a lot of room reflections. In a nice sounding room though ORTF gives the most natural acoustic guitar sound IMHO. I record acoustic guitars and group backing vocals with this method all the time. You get a lovely sound and spread with 3-4 people singing round an ORTF array.
     
  3. TornadoTed

    TornadoTed Guest

    Sorry I missed the bit about using ORTF on vocal, that's what you get from scan reading :oops: :oops:

    I don't see the value in recording a solo voice in stereo but as I mentioned it does work fantastic on a vocal group. I would have a go at the technique I suggested for recording guitar as it pays to try as many ways as possible, but if your way works then go with it. It's always the end product not the means of getting there with any music recording IMHO.
     
  4. David French

    David French Well-Known Member

    ORTF is meant for picking up a group of sound sources at a distance. It is just one arrangement of mics and is not special or great or anything like that. Also, if you use it close on a 'point' source, any slight side to side movement of the source will cause the image to shift drastically.
     
  5. ghellquist

    ghellquist Member

    Hi Keith,
    what you are describing in mic setup sounds more like XY to my ears. That is a well-tried technique for close micing stuff and can work also further away. The idea is to put the mic diaphragms as close to each other, but pointing in two different directions. A good starting point for angle between the mics is 90 degrees.

    ORTF is something different from what you are describing. It has the two mic diaphragms exactly 17cm from each other and pointing outwards at 110 degrees. 17cm comes from the ORTF beeing the french state radio, and I would expect any institution like that to train their operators carefully in using their approved techniques.

    Of course ORTF setup is only one of a million variations on setting up a stereo pair of mics. A very close variation is called DIN, short for German industry standard. And of course the two cannot be the same.

    Meanwhile keep on recording, if it sounds good it is good. But stop call it ORTF because it simply is not.

    Gunnar
     
  6. took-the-red-pill

    took-the-red-pill Active Member

    thanks guys.

    In response to your various posts:

    Gunnar

    I'm aware that this is not ORTF, and that's why I referred to it as "pseudo ortf." I don't know what to call this since it shares ORTF spacing but the XY angle.

    I guess we should call it: Pseudo Ortf Option Project...or POOP for short. :D

    Tornado Ted

    I am currently not in the greatest room in the world, as my studio is not built, hence the close micing to take out some room noise, instead of backing it off to get the benifit of the room, as ORTF is usually used.

    I will try an actual ORTF acoustic guitar once the room is built.

    I've tried an actual XY array and it was an ungainly pain in the caboose to work with. This is just a hundred times easier to work with, and the results seem to come out well.

    David

    I have listened to the guitar throgh my cans and I don't hear any wild variations from movement, though I could just be lucky.

    So other than not following the rules it sounds like it's not a tremendously bad idea, as long as I am aware of these issues. That and the results I'm getting are encouraging.

    Thanks again all

    Keith
     
  7. took-the-red-pill

    took-the-red-pill Active Member

    So I realise every room is different, but I'm just wondering what sort of distances you find to work well for acoustic guitar and BG vocals respectively.

    Thanks
    K
     
  8. TornadoTed

    TornadoTed Guest

    Took-The-Red-Pill. There aren't any hard and fast rules as you well know but generally 18"-36" on acoustic guitar and with backing vocals gathered around the mics about a 48"-60" away. I am in the enviable position that I have a lovely wood live room at my disposal with excellent acoustics. David French is right the image can change drastically with very little movement so I always get the guitarst to sit on a stool when using the ORTF method. I would also say that I only tend to record acoustic guitar with the ORTF method when it is in a solo situation. It gives a lovely natural sound with little or no processing. I usually close mic in mono when used with other instrumentation so I have more options on fitting the sound around other instruments in the mix.
     
  9. took-the-red-pill

    took-the-red-pill Active Member

    Thanks. Good info.

    K
     

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