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Pair matching microphones
Old 3 weeks ago
  #1
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Pair matching microphones

I was wondering about how much better pair matched microphones might be. They usually cost a bit extra. Then I wondered how matched some of my microphones were. So decided to test them. I set up a mike stand middle of a fair sized room. 12 feet from a single speaker. Used REW to test them. REW calculates the impulse response from a frequency sweep. Run the sweep swap mikes in the same exact position. Run the sweep again.

I was surprised the response and matching is mostly pretty good. You get some small differences from noise sources even just running the sweep twice especially below 50 hz. So I thought I would post the results and ask for discussion about it. Most of the up and down is the speaker/room. I also used 1/6th octave smoothing. This seemed to show the general response differences well. Even without smoothing these are the same response at high detail. Differences seem to be gentle and broad.

First I had three Shure KSM 32s. Pretty close match. Purchased 2nd hand and spanning a few years. The earliest with a different metal mesh on the cover was 1.9 db more sensitive than the other two though with the same response curve.
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Old 3 weeks ago
  #2
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Next up are three Audio Technica AT4033a mikes. I didn't adjust the level of any of them. All 2nd hand at various times of manufacture.
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Old 3 weeks ago
  #3
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A pair of Avantone CR 14 ribbons. Purchased several months apart. One was 1.3 db louder than the other.
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Old 3 weeks ago
  #4
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A pair of Avantone CK1 with the omni capsule. Serial numbers differ by a couple hundred.
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Old 3 weeks ago
  #5
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Avantone CK1 with the cardioid capsules. These differed by 1.3 db in level.
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Old 3 weeks ago
  #6
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Next a pair of CAD M179 microphones made about a month apart. First up is the omni mode.
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Old 3 weeks ago
  #7
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Same pair of CAD M179 microphones in cardioid mode.
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Old 3 weeks ago
  #8
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Now the CAD M179 microphones in figure 8 mode. There was a 1.5 db level difference in this pattern.
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Old 3 weeks ago
  #9
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I think un-matched pairs are mostly fine, as you have shown . . .except when they aren't

I have two pair of DPA 4011a, two matched at the factory, two not. The two that are not matched are from pretty differences in year of manufacture and they sound not alike in a very audible way. They both sound good, as expected, but they don't match as a pair. Perfectly good as solo spots, maybe even on a piano but I wouldn't use them as a main pair. A casual listener wouldn't hear it but I'd know

D.
Old 3 weeks ago
  #10
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Recently bought a pair of Sennheiser MKH30's and the matching consistency was incredible. My matched pair of MKH8040 are not as tight in matching. Also have 2 not matched MKH8020 without XLR part and matching is a little more off but barely audible. Also my Beyer MC930 are extremely well matched.
Old 1 week ago
  #11
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Best piano recording I ever made was with two completely different microphones (that was all I had at the moment). So for recording piano, I wouldn't worry about whether a mic pair is matched or not.
Old 1 week ago
  #12
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Well, guess what, none of us have matching ears, either. But that is not the point, is it?
Old 1 week ago
  #13
Quote:
Originally Posted by dseetoo View Post
Well, guess what, none of us have matching ears, either. But that is not the point, is it?
You are quite right, that is not the point. Our ears have nothing to do with this.
Old 1 week ago
  #14
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Quote:
Originally Posted by dtf View Post
You are quite right, that is not the point. Our ears have nothing to do with this.
Come to think about it, our ears have everything to do with it. Ultimately, all the recordings we make have to please some ears, recording engineers’ first I would hope.

Having totally matched microphone as main pair helps to bring our ears closer to the recording venue, in a particular seating. However, it certainly is not detrimental if the mics are not matched, especially if the mismatch is minor. Technically speaking, the only time a matching pair mic matters is if one wants to record a point source that is placed right in the middle of the two microphones and that particular recording needs to be mono compatible. Personally, I think matching main stereo pair is overrated. Frankly, how can any listener tell if the pair is not perfectly matched from a live concert recording? As I stated before, our ears are not perfectly matched.
Old 1 week ago
  #15
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In a worst case scenario, if we are listening to a pair of stereo arrayed mics with say a dip in a frequency area on one mic and a corresponding lift in that same frequency in the other mic. When that frequency is reproduced by an instrument in the soundfield, it will appear to move towards the mic with the lift...especially if in the zone of the ear's maximum sensitivity.

Yes, 'tis an extreme example, and not likely with the calibre of mics we generally use, but such a phenomenon could still account for image wander or imprecise stereo stability even in a 'typical' pair of same model, non-matched mics ?
Old 1 week ago
  #16
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Matched pairs

Well, anyway it makes me feel better.
Old 6 days ago
  #17
Quote:
Originally Posted by dseetoo View Post
Personally, I think matching main stereo pair is overrated.
This, in principle, I agree with. And you are right that listeners will likely not know if your mics were paired, or not. But that is true of many situations - a listener will not know if one of the mics gave 12 dB less output and I had to compensate on the preamp (though they might notice a bit more hiss, depending on the quality of the amplifier).

With omnis, I do think it matters, because e.g. with an A/B, both your ears hear the signal of the left loudspeakers, as well as the right loudspeaker.

Added to that, I want tools that do not introduce mistakes - an A/B of 2 microphones with a different frequency response will result in frequency dependant problems in imaging.

You should not forget that the real world situation is that most microphones (Neumann, Schoeps, Sennheiser etc.) simply are already well-matched to begin with, so any differences are often within critical tolerances.
Old 6 days ago
  #18
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Quote:
Originally Posted by dseetoo View Post
Personally, I think matching main stereo pair is overrated.
When recording with a pair AB, XY, ORTF etc. Matching is not optionnal.
I had a pair of cardoid sdc that had some problems : sometimes they matched very well but sometimes their responses didn't match (humidity sensibility of one mic ?). Not a big difference but when listening stereo recordings with headphones the stereo image was destroyed. I had to change this pair with a really matched pair.
Old 6 days ago
  #19
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Quote:
Originally Posted by dseetoo View Post
Well, guess what, none of us have matching ears, either. But that is not the point, is it?
Headphone listening? Or matching loudspeakers in symmetrical lounge-rooms?
Old 6 days ago
  #20
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Quote:
Originally Posted by mathieujm View Post
When recording with a pair AB, XY, ORTF etc. Matching is not optionnal.
I had a pair of cardoid sdc that had some problems : sometimes they matched very well but sometimes their responses didn't match (humidity sensibility of one mic ?). Not a big difference but when listening stereo recordings with headphones the stereo image was destroyed. I had to change this pair with a really matched pair.

In your case, one of the microphone is defective. There is nothing to talk about if it is a defective microphone.

I am saying that with a pair of reasonably unmatched microphone will be just fine as a main pair.

I have perfectly matched Schoeps capsules and capsules far apart in vintage(30+ years apart) and they all sound fine used as main pair. The unmatched capsules can be as far as 3dBs apart but they are still fine as a pair with gain compensation.

Frankly, where you stick the microphone on the stage will make far greater difference in stereo image. Besides, I never record single stationary sound source placed right in the middle of two microphones.
Old 6 days ago
  #21
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Quote:
Originally Posted by David Spearritt View Post
Headphone listening? Or matching loudspeakers in symmetrical lounge-rooms?

If the source is a big orchestra or a such asymmetrical sound field, it does not really matter if the main pair is perfectly matched, or not.

You can easily test your ears by listening to some pink noise on a pair of can and hard pan left to right. I am almost 100% certain you will find your ears are not that well matched, at least less well matched than your microphones and headphones. As we age, our hearing will age and age unevenly but we learn to compensate. But that is another conversation.
Old 6 days ago
  #22
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Quote:
Originally Posted by David Spearritt View Post
Headphone listening? Or matching loudspeakers in symmetrical lounge-rooms?

Suppose you have a pair of well-matched speaker placed in a perfectly symmetrical room, you sit in the middle of the room between the two speakers. Now, place a test microphone at your left ear and do a sweep of the left speaker, then place the test microphone at your right ear and do the same sweep of the right speaker. What is the likely chance that the two test results will be remotely close? If you think the poor result is due to the speakers not being well matched, you can use the same speaker for this test and move it from left to right position.



What I found was that it is much more forgiving using a pair of unmatched microphones than that of front to back symmetry of a figure 8 mic used in a MS configuration. I think most of time, we can tweak the gain and possibly a little EQ between the microphones to make them work well enough whereas you can't really compensate easily with a figure8 microphone that is not symmetrical.
Old 6 days ago
  #23
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Quote:
Originally Posted by dseetoo View Post
I think most of time, we can tweak the gain and possibly a little EQ between the microphones to make them work well enough...
I suspect this is true. But... isn't the point of having a factory matched pair that we don't have to do this work in post?

Really, I'm perfectly happy to give Schoeps it's $50 USD matching fee just so I can avoid tweaking gain and playing with EQ to make my stereo pair match.
Old 6 days ago
  #24
A comment from the cheap seats...
We have 250 Schoeps, Neumann, DPA...etc. There are a total of 0 matched pairs.
Well made microphones that are working correctly do not need to be matched. When we sent a a dozen or so Schoeps MK2, 2s and 5 to get refurbished, we found that they all were within the matched pair tolerances.... Some of them were made in the early 80's
All the best,
-mark

Last edited by mpdonahue; 6 days ago at 01:20 AM..
Old 5 days ago
  #25
Quote:
Originally Posted by mpdonahue View Post
Well made microphones that are working correctly do not need to be matched.
Of course, but that is because they already are matched - in other words, when the mics are within the tolerances of companies such as Neumann, Schoeps, DPA etc., they are similar enough for making great recordings. So, it is not necessary to order and pay extra for a specifically "paired" microphone.

However, dseetoo was arguing something else, namely that it is not so important that mics for stereo pairs share the same frequency response (which I do not agree with).

Best,
Dirk
Old 5 days ago
  #26
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Quote:
Originally Posted by dtf View Post
Of course, but that is because they already are matched - in other words, when the mics are within the tolerances of companies such as Neumann, Schoeps, DPA etc., they are similar enough for making great recordings. So, it is not necessary to order and pay extra for a specifically "paired" microphone.

However, dseetoo was arguing something else, namely that it is not so important that mics for stereo pairs share the same frequency response (which I do not agree with).

Best,
Dirk
I am sorry, but that is not what I am arguing about, at least I didn't intend to. I am talking about within the same model of microphones that are not "factory matched".

However, as I said before, I do have same type of Schoeps capsules that are 3dBs apart (not just in sensetivity domain) but with a slight amount of adjustment in the mix they function perfectly fine as a pair.

Further more, I had experimented with two entirely different microphone as a pair, one MKH8020 and one Schoeps MK2H. Afterthe correction profile was inserted (either direction) I came to the conclusion that they worked just fine as a pair. Granted, both are highend mics to begin with. I have no need to ever do this in a real recording project but it was interesting as a study.

Best regards,

Da-Hong
Old 4 days ago
  #27
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Maybe an advantage of doing MS recording. One mic is a figure 8. One is a cardioid (or fig 8). These essentially form a composite virtual microphone for right and left channels. They aren't going to match for directionality or frequency response. However by definition the virtual right and left microphone inherently have completely identical responses.
Old 4 days ago
  #28
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Quote:
Originally Posted by esldude View Post
Maybe an advantage of doing MS recording. One mic is a figure 8. One is a cardioid (or fig 8). These essentially form a composite virtual microphone for right and left channels. They aren't going to match for directionality or frequency response. However by definition the virtual right and left microphone inherently have completely identical responses.
For sure! I use 'mismatched' mics for MS often - typically playing with different cardioids or sub-cardioids for the mid. I usually use mics with similar voices, but I am not sure that is a requirement. Some experienced folks here even pair an LCD with an SCD. However, if you are going the 'purist' route with two figure 8s in MS (like Rolo46) I think matched mics are recommended.
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