Why so many microphones? Well, the short answer is that some microphones are better at some tasks than others. For example, if you are recording a bass guitar or a kick drum (base drum), you want a mic that will be sensitive to and respond smoothly to very low frequencies (in the 20 to 100 Hz range). [Hz is a unit for measuring frequency and means cycles (or vibrations) per second.] Such a mic typically has very poor response to frequencies over 10,000 Hz (See Figure 1), but you really don't care since bass guitars and kick drums reproduce essentially none of those frequencies. However, if you were to use that same mic to record an acoustic guitar or a violin, it would sound pretty "muddy," because those instruments create many frequencies in the 10,000 to 20,000 Hz (10kHz to 20kH) range, and those frequencies produce the brilliance that you associate with violins and acoustic guitars.
Let me digress for a second and give you a little technical information about microphones. (If you find the technical stuff boring, you may want to skip ahead about 4 paragraphs.) The purpose of a microphone is to turn sound waves into electric currents so they can be amplified or recorded. There are several varieties of microphone types, and each type performs this function in a slightly different way. The three types of mics typically found in a recording studio are: (1) the dynamic microphone, (2) the ribbon microphone, and (3) the condenser microphone (sometimes called a capacitor microphone).
With a dynamic microphone, the diaphragm (the part receiving the sound waves) is attached to a coil within the field of a permanent magnet. As sound causes the diaphragm to vibrate, it induces a current in the coil. This is the exact same principle as a loudspeaker, except in reverse—an electric current causes the coil in the speaker to move producing sound in the diaphragm (speaker cone). Dynamic mics are rather robust and are often used on-stage by singers. They are also good for recording speaker cabinets of electric guitars. They are called dynamic because they require no external power.
The ribbon microphone is actually another type of dynamic mic in which a thin metal ribbon (instead of a diaphragm) is inserted into a magnetic field. Sound vibrating the ribbon causes a current to flow. Ribbon microphones reproduce a wide range of frequencies fairly accurately and are often used for voice as well as instruments. The biggest disadvantage to the ribbon mic is that the ribbon is very delicate and can be easily damaged by loud sounds or someone simply blowing on the mic. For that reason many recording studios today do not use them, although some still do.
The condenser microphone works on the principle that changing the distance between the two plates of a condenser (capacitor) causes the capacitance to change inducing a change in current in the circuit. The microphone diaphragm is actually one plate of the condenser. In order to function, an electric current must be maintained on the plate. Therefore, these microphones require an external power, unlike dynamic mics. The external power is called phantom power for reasons that escape me. A condenser mic is capable of reproducing a much wider frequency response than is typical for dynamic mics.
Now back to our discussion of why so many mics. For decades microphone manufacturers have been trying to design a better microphone, one that has a flat response curve from 20 Hz to 20 kHz. And microphones have improved immensely over the years, getting closer and closer to the goal of flat response. However, a funny thing happened on the way to the "perfect" microphone. To some people's ears, some of the microphones built back in the '40s, '50s, and '60s sounded better than some of the new mics with relatively flat curves. They were described a "warm," "smooth," or "rich." So what happened? Well, by happenstance or design (who knows?) these classic microphone emphasized certain frequencies that tended to make vocalists sound better. Today many of these classics are very much sought after. However, some of the "classics" may not be all that great, since as various parts of the microphones have worn out or failed, many of the parts are no longer available (in particular, the vacuum tube and diaphragm parts). As a result some people say that refurbished classics may no longer exhibit the sound for which they have become famous.
To my knowledge, no one has yet manufactured that "perfect" mic. If you look at the response curve of a typical condenser microphone made today you will still see hills and valleys in that curve (See Figure 2). For that reason, each microphone will sound slightly different. A microphone that sounds very good for one vocalist may sound completely wrong for the next. Also a mic that makes male voices sound great may do nothing for female voices, and vice versa. For that reason, we have a number of large-diaphragm condenser microphones. (Typically the small-diaphragm condenser mics are used for instruments and large-diaphragm mics are used for vocals, but not exclusively—whatever works best.) Our collection of mics allows our clients to audition various mics to find the one that sounds just right. Two of our best mics are the Neumann M-147 and the Neumann U87. Arguably some experts say these mics come very close to sounding like a Neumann U47, probably the most famous of the classic mics. We also have an AKG C414, which some vocalist swear by. We have several other condenser mics that work well for some vocalists. We will find the mic that works best for your voice.
So there you have it in a not-so-much-of-a-nutshell the answer to why so many mics. If you have questions about microphones or any of our equipment, please contact us.