Whether you’re experimenting in your basement or laying down tracks at a large format studio, your microphone choice will impact the outcome of your recording. There are many ways to achieve a great sound and it all depends on what works best for you and your project.
Let’s start with the basic functions. Microphones are acoustic-to-electric transducers that convert sound waves into an electric signal that is able to be amplified, recorded and played back. All microphones have a diaphragm. This is a thin piece of material suspended within the microphone that vibrates when struck by a sound wave. This causes other internal components to vibrate and induce a small electric signal.
Microphones are commonly categorized by their transducer principle – how they convert acoustic sound waves into an electric signal. In this installment, we’ll discuss a few of these types and how they differ.
Dynamic mics work by electromagnetic induction.Simply put, the diaphragm is attached to a small wire coil that is fixed around a permanently placed magnet. As sound waves enter the mic, the diaphragm vibrates causing the attached coil to move around the magnet. This produces electric signal within the coil. Dynamic mics are the most rugged and durable of all. They handle high levels of signal and are often used to record drums or loud amplifiers. In general, they are less expensive than ribbon or condenser mics (read below). If you’re looking for something solid, versatile and dynamic, try the Shure SM57 as a starting point. It costs about $100 and can be used in a huge variety of recording situations. For drums, the 57 is a standard snare mic. Throw one on your amp speaker and move it around to see how it picks up sound in different positions relative to the center. If your amp has two speakers, try pointing one towards each for a thicker sound. Several manufacturers make low cost dynamic mics, such as the Audio-Technica ATR2100USB and the Nady SP4C, which run for less than $15, and are great for experimenting on a budget.
Ribbon microphones also work by electromagnetic induction. The diaphragm is a small piece of extremely thin ribbon that is corrugated and suspended into a magnetic field. As sound waves enter the mic, they cut across the ribbon’s slits and cause it to move back and forth. This creates an electric signal within the magnetic field. Because of this fragile design, generally ribbon microphones are more sensitive than dynamic mics and have a lower output (lower sound/signal). If used on a guitar or bass amp, make sure to either point it off-axis (not directly on the speaker) or keep the gain level at a reasonable level. Many ribbon mics offer a darker, warmer sound and can sound great on certain acoustic guitars, as drum room microphones or on reed instruments. Historically, ribbon microphones feature a bi-directional polar pattern, meaning they pick up sound from the front and back but reject it from either side. However, innovations in ribbon design mean modern ribbon mics are now able to handle more signal and feature alternative pickup patterns. The Beyerdynamic M160 is a perfect example of this. It features a hypercardioid pattern, meaning it picks up sound from the front and sides and rejecting sound from the back.
Condenser microphones function differently than dynamics and ribbons. These mics have two plates inside. One is stationary and one fluctuates as it responds to changes in pressure from sound waves entering the mic. These movements between the plates induce an electric signal. Because they are generally more sensitive to the nuances of sound than dynamic mics, condensers are often used on string instruments and vocals. They require an external power source, usually in the form of 48V phantom power which can be activated on most audio interfaces and recording consoles. Neumann’s U87 and KM184 stereo pair, as well as AKG’s C414, are all notable condenser mics found in many professional studios.
Slight variations in mic placement can alter the captured sound, however there is no right or wrong way to mic your instrument or amp. Finding out the best sound for you may take time. Don’t be afraid to try something outside of the box! It may lead to something we haven’t heard before.