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Earthworks ORTF -- in action! Condenser Microphones
Old 27th May 2006
  #1
Talking Earthworks ORTF -- in action!

Truth is, there's not much to see. If these didn't have to be big enough for the XLR cable, you probably wouldn't see anything. Any yet... and yet... I find that placing these infront of anything... full orchestra, drum kit, typewriter... you get a perfectly honest and beautiful image of what's there, the real true-life enchilada.

Which works for me.
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Earthworks ORTF -- in action!-earthworks-orft-action.jpg  
Old 27th May 2006
  #2
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GP_Hawk's Avatar
Beautiful sight! And what may I ask was this for?
Old 27th May 2006
  #3
I've been using these little beasties for anything and everything, ever since I got them about a month ago. Live choruses, chamber singers, orchestras, piano recitals, twenty-piece jazz bands. You prop them on a mic stand and they deliver a crystal-clear image of whatever's infront of them. It's so accurate you would swear that's exactly what that [whatever it was] sounds like.
Old 27th May 2006
  #4
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Umm, they look like omnis. Yes?

ORTF is cardioids, yes?

If they are omnis, I'm interested in how you handle phase and panning issues, and summing to mono.

I love the sound of omnis. So any advice or suggestions is welcome.

Cheers,

Haigbabe
Old 27th May 2006
  #5
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Earthworks

Yes they are omnis & I agree, they sound great. I use them with a Jenklin disk to help improve stereo imaging & separation.
Old 27th May 2006
  #6
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Quote:
Originally Posted by dtmprod
Yes they are omnis & I agree, they sound great. I use them with a Jenklin disk to help improve stereo imaging & separation.
It is Jecklin
Old 27th May 2006
  #7
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Haigbabe's Avatar
 

Quote:
Originally Posted by dtmprod
Yes they are omnis & I agree, they sound great. I use them with a Jenklin disk to help improve stereo imaging & separation.
Thanks.

So not ORTF.

ORTF is cardioids, yes?

Always with Jecklin?

Quote:
I use them with a Jenklin disk
Except in the photo?

If not, how do you handle imaging and phase?

Cheers,

Haigbabe
Old 27th May 2006
  #8
They are indeed omnis, so an ORTF array might seem counterintuitive... but in actual practice they work great without any phase anomalies. How can this be? I dunno.... panning the tracks hard left and right gives a really nice stereo image. And the one time I broke ALL the rules and faced them both forward, so you got two capsules six inches apart, tailor-made for weird phasey distortions... they sounded fine. I was all set to use one, or the other, but not both together... but it was fine.

Something about these things... they are not really "microphones" so much as "reality capture devices."
Old 27th May 2006
  #9
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Quote:
Originally Posted by joelpatterson
They are indeed omnis, so an ORTF might seem counterintuitive
ORTF is cardioids, yes?

Cheers,

Haigbabe

PS It was when I worked for Radio France in the 80's
Old 27th May 2006
  #10
Right, right, the ORTF spec is for two cardioids, about six inches apart, facing away from each other at 110 degrees.

So this breaks all the rules.
Old 27th May 2006
  #11
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Just to clarify - it might not be obvious to all who read this thread: You don't get ANY phase issues as long as one mic goes to L and the other to R. Phase issues occur only when the signal is summed in some way (ie, by panning them not fully to L and R).
Using omnis with less than 2 ft space between them is common practice in recording soloists: they don't "jump" between the speakers since the time differences between the signals are too small to really put something into one speaker only, and it still sounds spacious - BECAUSE of the phase differences and, to a certain extent, because of the non-directionality.
Angled omnis normally will produce frequency-dependent level differences correlated to the direction the sound comes from, just like with a Jecklin Disc. I don't know how strong this effect isw/ the Earthworks mics (probably not very strong, since the diaphragm is very small), but there are many people who think that such frequency-depeden level differences are not desirable. Theoretically, they're right. In practice, I've seen and heard lots of angled omnis and didn't find anything bad about it. If it sounds good, it is good, as someone said.
Old 27th May 2006
  #12
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Haigbabe's Avatar
 

Quote:
Originally Posted by pkautzsch
Just to clarify - it might not be obvious to all who read this thread: You don't get ANY phase issues as long as one mic goes to L and the other to R. .
Interesting.

I can post you some examples if you like which may give pause for thought.

And there are quite a few people who might view your opinion as, well, let's say, different.

But you may well be right.

Quote:
Phase issues occur only when the signal is summed in some way
Such as clock radios, TV, some car radios, elevators, hair salons, supermarkets, music-on-hold, shopping malls, etc

Cheers,

Haigbabe
Old 1st June 2006
  #13
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Dale's Avatar
 

Quote:
the ORTF spec is for two cardioids, about six inches apart, facing away from each other at 110 degrees.
https://www.gearslutz.com/board/images/sm...nu/yinyang.gif
there is a discrepancy, ORTF is either 16.5 or 17 cm spacing.
that is 6 3/4 to 6 7/8 approx.
they work well using the NOS position too, ( 90 degree / 30 cm) which yields a stereo perspective that is flatter then the ortf, great left to right but...
it works real well with big band gigs.
which model do you have there? the QTC 40 or 50??

dale
Old 1st June 2006
  #14
My chums that record military & 'big bands' love these & use em for main pair..
Old 1st June 2006
  #15
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Dale's Avatar
 

Quote:
Originally Posted by Haigbabe
...If they are omnis, I'm interested in how you handle phase and panning issues, and summing to mono.

that is the beauty of ORTF / NOS they were devised by radio france and radio netherlands
their setups are optimized for summing to mono. broadcast radio and tv were mono.

dale
Old 1st June 2006
  #16
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Quote:
Just to clarify - it might not be obvious to all who read this thread: You don't get ANY phase issues as long as one mic goes to L and the other to R. Phase issues occur only when the signal is summed in some way (ie, by panning them not fully to L and R).
To what does this statement refer to, listening on headphones or listening from a pair of loudspeakers?
Old 1st June 2006
  #17
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The statement about phase issues refers to all kinds of two-channel playback. To get a really natural sound on headphones it is necessary to record in a head-related way (i.e. dummy head, Jecklin disc or other separation devices) to get the typical HRTF response. When listening to speaker playback, the listener's own head produces this HRTF response (of course...), so we don't need ear signal for speaker-based playback. As the signals of both speakers reach an ear AT DIFFERENT TIMES and different levels - the "correct" one being earlier and louder and thus making the mind suppress the "wrong" one (Law of the First Wave Front), phase issues should not occur.

But, as Haigbabe points out very correctly, there *is* of course summing in any mono playback device, and thus for music intended to be played back on such mono devices one should theoretically only use coincident techniques that pan only by level differences. I may, however, add that people who buy classical CDs usually have stereo playback that often comes near the 60° triangle studio standard, and thus one can safely do spaced setups for classical. As is discussed in that other thread about mono compatibility checking and mono mixing, it all depends on where the recording is to be played back.

The original ORTF setup developed by French Broadcasting Association is 170 mm between the centres of the two capsules and 110° as is the Schoeps ORTF mic which was developed for the French broadcasters. I don't think, though, that those 5 mm will result in audible differences. Personally, I prefer the term "equivalence setup" since this means all setups involving both time and level differences and allows for lots of variations.
Old 1st June 2006
  #18
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Well, in my experience, spaced mic techniques do have phase issues when listening on loudspeakers and not just when summed to mono. One only has to listen to solo oboe or clarinet recorded with a pair of spaced omnis to hear interferance and comb filtering.

I think the main mechanism is that each ear hears both loudspeaker sources (mics) where wavefronts were recorded with a time/phase difference due to the spacing. If you block one ear and listen with the other, you will hear interferance.

For solo winds or other sources where the wavelength nicely couples with the normal spacing distance of a spaced pair, I always reach for a Blumlein pair to eliminate this significant problem and bring clarity to the recording.
Old 1st June 2006
  #19
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pkautzsch's Avatar
 

Quote:
If you block one ear and listen with the other, you will hear interferance.
This is, in a way, summing to mono. Funnily, you won't hear interference when listening with both ears...

BTW that's a great idea you gave me. Blocking one ear as The Safe Way to Find Out Whether a Recording was Made with a Spaced Setup
Old 1st June 2006
  #20
Quote:
Originally Posted by Dale
which model do you have there? the QTC 40 or 50??

dale
Uh... the QTC 30. But it's almost a QTC 40!
Old 1st June 2006
  #21
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Quote:
Originally Posted by pkautzsch
Funnily, you won't hear interference when listening with both ears...

...unless you (the listener) move.
Old 1st June 2006
  #22
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Quote:
This is, in a way, summing to mono. Funnily, you won't hear interference when listening with both ears...
I disagree with this as well. My point is that both ears hear interference, two slightly different mono versions of it, which clouds and confuses the sound. A blumlein pr on the same source is like focussing a lens, all the confusion and smearing goes away. Its not pronounced, but I can tell a spaced omni recording of solo winds a mile off.
Old 2nd June 2006
  #23
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Quote:
Originally Posted by Bob Ross
...unless you (the listener) move.
...Exactly...I admit it's sort of idealistic. But the over-serious hi-end consumer will probably not move a lot, and the not-so-serious consumer who moves will probably not hear such details.
Coincident setups usually have less "spaciousness" than spaced setups (I explained in another thread that spaciousness has to do with the lack of phase correlation - precise image has to do with the presence of phase correlation...) - so it's a question of aesthetics. Personally, I (and my customers) prefer spacious sound with muddy imaging for larger ensembles, and less spacious sound with good imaging for smaller ensembles where each instrument has their own part.
Old 2nd June 2006
  #24
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Plush's Avatar
That's called a spaced omni--that's what it's called.

Perfectly useable--you may want to try spacing them farther apart, however
Old 3rd June 2006
  #25
I always thought that the correct included angle for the ORTF array was twice the angle that produced a sensitivity drop of 3 dB in the particular mic being used, that angle being typically 55º in a typical hypercardioid. The purpose of this is simply to prevent overemphasizing the centre of the soundstage.

In thinking it through, I don't know why a pair of omnis in this arrangement would be much different from cardioid or hypercardioid when it comes to the phasing weirdness, mono compatibility or panning issues that are a given with any A-B stereo micing technique. You would think the Decca tree is particularly susceptible, given the very wide spacing of the outboard omnis.

I would expect a substantial build up of centre of the soundstage with omnis - even slightly directional ones - but maybe that just happens to work in most cases.
Old 3rd June 2006
  #26
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Mr. Dawkins has brought up an interesting and little known fact. That is that the original spec for French Radio ORTF specified that hyper-cardioid capsules should be used. They still can be used, but cardioid is much more common and have been chosen for the MSTC64 ORTF stereo mic "system" made by Schoeps.

Included in the above thinking, one cannot expect good performance from omni's used in ORTF arrangement because you have removed the time of arrival cues that make ORTF work.

A-B technique includes omnis spaced much wider than used the Decca Tree. Decca Tree side mics are not all that wide in comparison to some A-B set-ups that have, as their desired result, enhancement of spaciousness in the recording.
Old 3rd June 2006
  #27
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Dale's Avatar
 

Quote:
Included in the above thinking, one cannot expect good performance from omni's ORTF arrangement because you have removed the time of arrival cues that make ORTF work.
this might have been the original theory, using the existing technology(1930's).
this setup is what Earthworks recommended to me.(qtc-1mp)
I had my doubts but when I put it to the test (real life use)
I have found it to work extremely well, a balanced soundstage with great left to right and front to back depth which also includes summing to mono.

dale
Old 3rd June 2006
  #28
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pkautzsch's Avatar
 

Quote:
Originally Posted by Plush
Included in the above thinking, one cannot expect good performance from omni's used in ORTF arrangement because you have removed the time of arrival cues that make ORTF work.
I don't understand this: the time cues depend on the spacing between the mics, right? Why is the spacing removed by using omnis?
What *is* removed is the level differences though, except for possible frequency-dependent directivity. Or am I missing something?

Quote:
Originally Posted by Russell Dawkins
to prevent overemphasizing the centre of the soundstage
Looking at a typical orchestra setup, it is obvious that the instruments in the centre are farther to the back than the instruments beside the conductor. They make up a semi-circle. In a typical ORTF position this can do something like 3 - 4 dB difference. That they still come up by about 2 dB is, to my perception, not bad, since it gives the violas a little bonus against violins and celli. I don't think (yet not positive) that ORTF setup was developed for drums or straight lineups, but mainly for orchestra recording. If soloists are preferred a little, this seems good to me...
BTW: all conventional setups prefer the centre of the soundstage, since this always is the nearest. It doesn't necessarily mean the centre is louder, but it's always more "present" in terms of treble. That's why with main-only setups you usually have to be a lot farther away to get a good balance than with main+outrigger+spots.
Old 3rd June 2006
  #29
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EDIT : I was replying the same time as pkautzsch. Sorry for the double thing. But i leave my post because my question is a bit different.



Quote:
Originally Posted by Plush
.

Included in the above thinking, one cannot expect good performance from omni's used in ORTF arrangement because you have removed the time of arrival cues that make ORTF work.
I don't understand this. Why are the time arrival cues removed when you use omni's ?

I thought time arrival differencies "make" the stereo in spaced techniques. In coincident techniques the level differencies give the stereo effect because the left pointing (cardiod) mic is picking up less of the right soundstage and vice versa. This mimics the masking effect of the head .
Or so i thought.

The ORTF arrangment is a mixed spaced/coincident technique, isn't it ?

Or do you mean the distance between the mics is too small as a SPACED PAIR in this arrangement.

Could you please explain ?


Thanks, Hans
Old 3rd June 2006
  #30
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I think what Plushy meant is that with omnis, you have removed the intensity differences which is one "half" of the cues produced in an ORTF pair, the time of arrival cues being the other "half" which are still there with spaced omnis, due to the spacing.

But I have found that with omnis, you need much more than 110cm to get any sort of useful image cues, more like 400-600mm.

So the original post in this thread with picture, while calling it ORTF, is in fact no-where near it.
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