Hands On - Quality Microphones (part 2)
So why spend all this money on a microphone, or microphones, when you can spend much less and still get a flat frequency response and a crisp clear sound? The answer is that some mics have that certain something that make them special. Its very difficult to say what it is but once you have compared one of these mics against an ordinary £300-£400 model then youll know what the difference is. This difference is most marked when you are recording in stereo with two mics for overall pickup and also when you are recording vocals, which brings me back to my first point With relatively few exceptions you will find that most commercially successful recordings are made using these very high quality mics for the vocals. It makes the difference between a product that will stay on the shelf and a product that people in their thousands will buy. Yes really!
Way back in the mists of history, the engineers at Neumann decided to make a mic that would beat the best then currently available. As was the style at the time, it would have a fairly large diaphragm, and it would operate with those new-fangled transistors which were just beginning to oust valves as the active circuit device of choice. Add to that powering from a 48 volt phantom power supply, when it was still quite common for mics to use inconvenient dedicated mains power supplies, and the option of an internal 22.5V battery (which now appears in Neumanns price list at £13!) and you had what was considered in those days a very desirable mic. The strange thing is that the Neumann U87, now reincarnated as the U87 Ai, is still a very desirable mic after all these years. I find it very surprising that as technology makes such tangible improvements in every other field of sound recording equipment, that the old mic designs, tweaked for lower noise and higher SPLs, are still subjectively among the best.
Like the AKG C414 and Beyer MC740, the Neumann U87 is a multipattern mic with a double diaphragm. The outputs of the two diaphragms are combined within the mic to give omnidirectional, cardioid or figure-of-eight patterns. Id be willing to bet however that most U87s are left set to cardioid for at least 364 days out of 365. Compared to modern compact microphones the U87 is big and bulky, which is partially the result of the large diaphragm. Once upon a time, diaphragms had to be large to capture enough sound energy to produce a reasonable signal to noise ratio at the output. In fact, even now you would expect a large diaphragm mic to have a better noise performance. The problem the engineers had with the large diaphragm, of this mic and similar ones, was that the mass of the diaphragm created a resonant frequency which was within the audible range. If you look at the frequency response chart of the Neumann U87 Ai you will see a peak at around 10kHz which is probably produced as a result of this resonance. The engineers had a problem with this because it didnt look right on paper, so they started designing small diaphragm mics which measured better but somehow didnt have the same sound that people liked, and still like.