combined reply to a few different messages above:
-- At the AES show, actually I don't see myself in the above photo; the darker-shirted belly is that of Dr. Helmut Wittek, co-CEO of Schoeps in Germany, while the guy with the Starbucks cup, perhaps inadvertently showing "the finger" while talking, is Scott Boland from Redding Audio, Schoeps' distributor in the U.S. and Canada. -- About 90% of the smaller, easily stolen items on display (e.g. the majority of the amplifiers and nearly all of the capsules) are dummies with serial number 00000 or the like. They might give disappointing results if you tried to record with them. From time to time some of them get stolen, and I've always wondered what people actually do with them. A kind of "collector" mentality is fairly prevalent among people who record sound, though, so maybe it's not that mysterious.
-- About shotgun mikes, the thing that always needs to be remembered is that their pickup pattern gets narrow only above some frequency that's generally in the upper midrange. That frequency is a function of sound wavelengths in comparison to the length of the interference tube in front of the capsule; the longer the tube, the lower the transition frequency. If a sound source is (say) 90° off-axis, its pickup isn't affected by the tube in the bass or most of the midrange. Then above the transition frequency it starts to be filtered--but irregularly so, with peaks and dips depending on the frequency, the exact angle of arrival, and certain details of the tube's construction.
If you're recording outdoors, or in a dry indoor acoustic and/or close to the intended sound source, this is all fine. The sound source that you want comes in on-axis, while any/all other sound sources are both (a) weakened by the mike's directional pattern in general and (b) filtered by the interference tube so that their treble content is weakened even further. The intended source will be distinctly the clearest-sounding thing that you pick up. All well and good. Note however that film and video sound mixers still have to get even a shotgun mike as close to the talent as the frame of the shot allows, and they also pay a lot of attention to precise aiming.
But if you use a shotgun mike in a reverberant space that has one predominant sound source (being spread throughout the space by a P.A. system) and you're not close to that sound source, the material reaching the sides of the mike will be largely the same as what's also arriving on-axis. The direct and reflected sound arrives via different paths within the room, each with its own path length (= delay time). So you're mixing together the original source plus multiple, filtered versions arriving at slightly different moments and various angles. Under those conditions, the effect of the interference tube is to create highly irregular phase cancellations in the upper midrange and treble--I mean peaks and valleys of 6 - 10 - 12 dB or even more in the response at various frequencies.
Shotgun microphones are thus a poor choice where diffuse sound is predominant. They're usable in such situations, but can't create a better balance of direct vs. reflected sound energy than what exists where you place them. They may look as if they were designed to solve the distance problem, but that's a category error/illusion. The only real solution is to place your microphones where a basically good balance already exists.
So much for mono pickup. If you want to use a pair of shotguns for stereo, remember once again that their directional pattern is quite different above the transition frequency than below it. So what distance and angle do you set between them? All the usual suggestions and formulas go out the window, being based on the assumption of a consistent frequency response across the microphone's pickup angle, which no shotgun microphone can possibly have. That leaves either spaced microphone (A/B) stereo or mid-side (M/S) recording, which nearly all "stereo shotguns" are based on. But M/S doesn't work well in diffuse sound fields. The "M" microphone needs to be where it could make a satisfactory mono recording if it were there by itself. (When the M/S technique was introduced in the early 1950s, all recording engineers were experienced at recording in mono, since that's all that had existed up to then, and European engineers went heavily for M/S stereo because it was compatible.)
In general the "reach" of a shotgun, even a long one, isn't much greater than that of a supercardioid--and of course below the transition frequency it's no greater at all -- zero. I think people really need to get the visual image (the "telescope" concept, or the telephoto lens) out of their heads.
Topic: Schoeps Shotgun Capsule: KMIT (Read 9614 times)