The next step is getting sound into the recording device. Sound gets into a recorder either by being plugged directly into the recorder with a cable, or by using a microphone to pick up the sound.
If you're recording an acoustic instrument or vocals, a microphone is necessary to convert the sound waves into electrical signals. What makes one microphone different from any other microphone? As a budding sound engineer, you should understand why engineers choose different microphones for different purposes.
Every microphone “hears” sound differently. Unidirectional microphones only hear what's directly in front of them, while omnidirectional microphones pick up everything from all sides. And figure eight microphones hear sound on two distinct sides. If you were trying to use one microphone to record a room full of sound coming from all sides, you would choose a microphone that hears sounds from all sides, the omnidirectional microphone. If you were trying to zero in on just one instrument without picking up other sounds, you would want to use a unidirectional microphone pointed right at the sound source.
Knowing what direction a microphone hears is usually the determining factor in choosing which microphone to use. You must choose the one that works best for what you're trying to record. See Chapter 9 for more information about different microphones and how to use them.
Some microphones also are more sensitive to certain frequencies of sound than others. This is called frequency response. You wouldn't want to use a microphone that can't hear very high signals clearly on a high-pitched instrument, or low signals on a low-pitched one. Microphones also color the sound they transmit; this is tied into frequency response. These colorations are what give microphones their distinct sound—“warm,” “clean,” or “clear” are terms commonly used to describe sound colorations. Because of construction differences between microphone manufacturers, every model sounds unique. With some training and experience, you'll be able to pick the right microphone(s) for your setup. Getting the right type of microphone is more important than buying a particular brand.
Microphones don't produce much signal by themselves. If you plugged one directly into a recorder, the sound level wouldn't be high enough to register a signal on your recording device. You could try to compensate by turning up the entire track, but unfortunately you'd turn everything up, including the noise. You need a preamplifier to raise the output of the microphone enough to make the signal clear and strong.
How many microphone preamps will I need?
You will need one preamp for each microphone you record at a time. If you don't record live groups, you might need only a few microphones, recording one or two tracks at a time.
Preamps are commonly built into mixing boards, studios-in-a-box, and computer interfaces, so you might not need to purchase these separately. You can also buy individual microphone preamps if your device has none or you need more. The number of microphone preamps that your mixer or other recording device has is a critical factor in determining if the gear is right for you. This is the time for you to evaluate how many microphones you plan to use simultaneously.
An instrument that plugs directly into the recorder is called a direct input. Microphones aren't necessary in these cases. Keyboards, synthesizers, drum machines, and certain guitar and bass amplifiers are equipped with “line outs” that can be plugged directly into a mixer or a recording device. A guitar or bass plugged in directly via a cable won't be line level, however; that is, its signal won't have enough juice to be heard. It also has the wrong impedance, which is an electronics term referring to how much force the signal has due to the way it impedes the outward flow of electricity.
Guitar and bass are very high impedance sources and generate very low output levels. Even though it appears that you can connect a guitar or bass directly to a recorder, you'll need a direct box, or DI, if you want to record a guitar or bass without an amp. A direct box simply takes a signal that is unbalanced or has the wrong impedance, and converts it to a perfectly balanced output suitable for plugging into a mixer. It's a common misconception that a DI box is all you need for guitar and bass. It's not. After the DI takes care of the impedance, you'll still need preamplification of some sort. This can either be a mixer or a computer recording interface.
Direct boxes come in two flavors: passive and active. Passive DIs don't require extra power to run; active DIs do. Active direct boxes require power for changing impedance and outputting balanced signals, while passive DIs do all their work through transformers. Every studio should have at least one direct box.
Another nice benefit of a direct box is that it can isolate nasty buzzes that studios encounter from time to time via a button called a ground lift. Even if your amplifier or keyboard has a line out, if you are getting buzzing that's driving you crazy, try a direct box between the output and the recorder's input, and flip the ground switch. Many times this will do the trick. Anyone who has played on stage has encountered a direct box; it's indispensable. If you plan to record bass, guitar, or certain keyboards that aren't line level, you will need a few direct boxes.