Topic: mics recommended for close micing live acoustic classical music?

[digifish_music]

You can buy them in matched pairs too.

How important is it - in general - to get a matched pair? Does it vary from one maker to the next, depending on how consistent their production runs are?

For an NT1-A probably not that important, their production is highly automated and has per-unit quality control. I remember hearing someone note that a Rode Matched pair was just consecutive serial numbers. It doesn't cost any more from what I have seen.

digifish

[RebelRebel]

well, it certainly makes life easier..Of course  microphones from "QUALITY" companies(if it were me I would go with the big 3..Gefell, Neumann, Schoeps(or DPA) are going to be so close that it wont matter necessarily whether they are matched(meaning on and off axis response, sensitivity "output") or not, but with some of the cheaper brands, it can be an issue. 

You can buy them in matched pairs too.

How important is it - in general - to get a matched pair? Does it vary from one maker to the next, depending on how consistent their production runs are?

[DSatz]

MRC01, for the kind of stereo recording techniques in which the main (or only) signals come from two microphones which are coincident or closely spaced, those two microphones must be well matched. With modern-day production techniques and automated quality control, the "serious" manufacturers can produce entire batches of microphone amplifiers which are matched well enough that they don't need to be specially selected. However, microphone capsules are still another matter. That's the critical component of a condenser microphone which mainly determines the sonic characteristics that people get all excited about one way or the other. It is the transducer which converts minute amounts of acoustical energy into electrical energy; it has one foot in both worlds, so to speak.

The problem is a conflict between marketing requirements and technical capabilities. If you are a microphone manufacturer and can convince the public that your microphones are so uniformly produced that no special matching is ever necessary, you've accomplished a valuable marketing feat. And it's certainly true that the better manufacturers' production tolerances have improved considerably in the past several decades. A typical pair of microphones from one of the better manufacturers (not specially selected) could be within 2 dB across the entire audible range at any chosen angle of sound incidence (excluding the region of a null in the pattern, of course). And that's a huge manufacturing achievement--but it's still wider than the tolerances on, say, an off-the-shelf Radio Shack receiver. This is not a problem that can be waved away with marketing slogans.

Again, the "serious" manufacturers make their capsules as uniform as possible, but typically, the actual variations in production are still several times greater than the variations in the response of microphone amplifiers. Mainly the variations are in overall sensitivity and the response at both ends of the frequency spectrum. For any given capsule type, if you know its 1 kHz sensitivity and its 40 Hz and 16 kHz response relative to 1 kHz, you can match a pair on that basis and do well.

Some manufacturers offer pairs of capsules that have been selected and matched on the basis of their actual production curves, which are not normally released to the public. Some importers claim to match pairs of capsules or microphones by ear; that could be feasible using a direct difference (subtraction) method of some kind, though it would still require careful measurement and record-keeping; otherwise the effort and concentration required would be almost unbearable. If anyone really can make such selections entirely by ear without difficulty, that would mainly imply an appalling lack of quality control at the factory! Even highly trained, talented listeners can't usually identify differences of (say) 1/2 a dB correctly even if they do perceive that something is different about the sound.

Meanwhile when you buy a pair of microphones it usually is only the amplifiers whose serial number you get to see. Not very many manufacturers serially number their capsules in a way that lets the customer see this numbering without disassembling the capsule head--and even if you can see the capsule serial numbers, that still doesn't tell you what you need to know (i.e. how closely did they turn out, and was there some other available pairing of equally good capsules that would have matched more closely?).

One prominent manufacturer (Neumann) recently changed over from offering "stereo sets" which their national distributors simply put together based on consecutive microphone serial numbers (which, of course, are the serial numbers of the amplifiers--not where the real problem is!) to "stereo sets" in which the factory selects the capsules and deliberately installs them on consecutively serially numbered amplifiers. Again, from the outside, the customer can't tell which procedure was followed, nor whether perhaps someone has meanwhile exchanged the capsule head(s) of one or both microphones, so this solution is helpful only up to a point. But for those who keep careful track of their equipment, it's a welcome improvement.

--best regards

[Gutbucket]

Hesitant to revive this thread, but I'd love to hear those 4050 samples of Teddy's.  Are they posted anywhere?  I'm considering having busman mod my ADK TL's which I use primarily for acoustic work, but would like to evaluate some other options as well.

[MRC01]

Actually I was going to suggest a pair of NT1-A's. To my ear this mic is the steal of the century. The low self noise is amazing in the studio setting. I often pair the NT1-A with a Sound Devices MixPre and together you can hear the termites eating the neighbours house    

The NT1-A does have a hump around 12K in the frequency response, however that said I have never noticed the mic to sound unnatural or brittle. some gentle EQ can fix that if it's an issue. Also being a large diaphragm it's supposedly not as good on fast transients, but again, I have never noticed anything but superb results on acoustic instruments and vocals.

Well I finally got a pair of NT1-As. I am driving them with my Zoom H4 and I'm happy with the results. Super clean, high resolution, great sound. As you mentioned, these mics are a little bright but not excessively so. For close-up recording which tends to enhance the brightness I EQ it down *slightly*, like -3 dB @ 11 kHz Q = 1.2. But to be fair I would probably do that with any other mic to avoid the artificially bright sound you always get with close micing. The noise level is incredibly low. Even with my cheap portable recorder I'm getting ambient noise about -66 dB on its highest gain setting (very quiet room...). And that's too much gain for recording my chamber ensemble, so the noise level is really even quieter. So low it is just not an issue.

I recorded full spectrum frequency sweeps to see how well matched they are. At all frequencies the levels match within 1.5 dB, and that includes whatever imbalances may exist in my recorder. I reversed the inputs and got the same. And it is not a matched pair, so either I got lucky or Rode has very consistent production.

Incidentally, no issues driving them with the H4. They are quieter than its built-in mics and they are sensitive enough to put out the same recording level at the same gain setting. I've done spectrum analysis on the recordings looking for problems but it's super clean.

[MRC01]

I forgot to ask my question: is a cardiod mic's response pattern spherical? That is to say, does it have the same response pattern in the vertical plane, as it does in the horizontal plane?

If the diaphragm is circular, I can't think of any reason why it wouldn't be symmetric vertically & horizontally - the pattern should be the same. Except perhaps for extreme angles where the mic body gets in the way. Is that true?

[ghellquist]

I forgot to ask my question: is a cardiod mic's response pattern spherical? That is to say, does it have the same response pattern in the vertical plane, as it does in the horizontal plane?

Well, sort of yes and no. If you take a good end-adressed small diameter microphone, say Neumann KM-184, the answer is quite much yes. This is because the whole design is "circular". If you take one of the side adressed large diaphragm mics, looking something like a U-87, they are pretty much spherical, but not totally so. The body is not quite "circular".

And then there are mics that are by purpose not spherical, two examples here:
http://www.microtechgefell.de/eng/prod/konden/kem970/kem970_0.htm
http://www.pearl.se/estart.htm  (check the Pearl Elm).

Gunnar

[DSatz]

MRC01, actually there is a bit of a paradox in the situation. ghellquist's reply is perfectly correct, but the directional pattern of an end-addressed, cylindrical microphone can never be perfect at high frequencies--while with a side-addressed microphone, the polar pattern in the horizontal plane can be audibly more consistent (though still not perfect) across the high-frequency part of the spectrum. So you generally have to choose between freedom of orientation and having the best available pattern at all frequencies.

In other words, fact #1 is that in an end-addressed cylindrical microphone, the pattern will be essentially the same in both the vertical and horizontal planes. That's just another way of saying that the microphone doesn't have a "top" or a "bottom" side--you can rotate it on its own axis while recording, and the sound you pick up won't change. But precisely because of the geometry which creates fact #1, fact #2 is that in either of the two planes (or any other plane that you choose), this pattern will vary at higher frequencies and at some angles of incidence. This is because sound at different angles of incidence will "see" a different shape than what front-arriving sound will "see", and will flow around or be reflected or diffracted differently.

Contrast this with a side-addressed cylindrical microphone: fact #1 will not be a fact any more (because in the vertical plane, the microphone has an entirely different shape than in the horizontal). But the situation for fact #2 changes, too, since no matter what the angle of incidence may be in the horizontal plane, the sound waves still come up against an identically-shaped and -sized side of the cylinder. As a result, the directional pattern in the horizontal plane can be somewhat better at high frequencies (of course that's just the housing--the capsule has its own acoustical properties, including its flat surface in the front and back). But you lose rotational symmetry completely, and the horizontal and vertical patterns can no longer be identical.

Does this make sense? It has some pretty interesting practical implications, I think. The cardioids I own which have the least peakiness off-axis at high frequencies are side-addressed, single-diaphragm cardioids. I like these microphones very much, as do many other classical musicians I've recorded with them. I'm at least as much of a gear slut as anyone else here is, yet as of autumn this year, I'll have owned these same microphones for 35 years--and if I absolutely had to sell all but two of my microphones, I would keep those two. (To be fair, I should explain that they're three-pattern microphones of a kind in which the omni setting is a true pressure transducer, unlike most other switchable-pattern microphones. Thus I would still have a considerable range of recording techniques available even if this gruesome choice were forced upon me.)

However, cardioids with a slightly brighter diffuse-field response seem to be more widely preferred in general. I don't always agree with this preference, but I do sometimes--for more distant miking in large, reverberant halls with smooth high-frequency absorption. Of my two favorite microphones of this second kind that come to mind, both are end-addressed--and that's no surprise when you consider the effects of the geometry.

--best regards

[MRC01]

Contrast this with a side-addressed cylindrical microphone: fact #1 will not be a fact any more (because in the vertical plane, the microphone has an entirely different shape than in the horizontal) ... you lose rotational symmetry completely, and the horizontal and vertical patterns can no longer be identical.

Hmmmm... so it would be useful for makers of side addressed mics (like the NT1-A) to provide two response graphs - one in the horizontal plane, one in the vertical plane. Mine came with only one graph. I assume it is in the horizontal plane.

That means if I mount my mics sideways, I do not know what the pattern will be, because it won't be the same as the graph in the manual.