How does a microphone work?
A microphone is a type of transducer. It converts sound pressure waves into electrical signals that can then be manipulated and amplified. Different technologies are used in different types of microphone to pickup the sound pressure wave. Some are better at picking up different frequencies compared to others and are therefore more suited to particular jobs.
A dynamic microphone works similarly to a speaker. It has a diaphragm that moves a coil over a magnet and creates an electric current in the coil that represents how the sound waves are moving the diaphragm.
The Shure SM58 (pictured right) has become the industry standard go-to microphone. At a high-end level, many will carry some in their kit as a just-in-case; but they are the most commonly used microphone for vocals just about everywhere.
A condenser microphone works similarly to a dynamic microphone but has a capacitor in it instead of a magnet and coil. As the sound waves enter the microphone, the distance between the two plates of the capacitor varies; producing the varying voltage for the audio signal.
Many manufacturers have their own condenser mics all with different frequency responses, frame shapes and sizes – all suited to doing different tasks. Remember there is no one correct mic for anything. It’s simply what you think sounds best for the job.
A Ribbon Microphone has a thin corrugated strip of aluminium suspended between two strong magnets. This strip vibrates when the sound waves hit it and create a tiny Voltage. This small voltage is then amplified to a more useable level encountered with most other microphones. Unlike the other types of mics mentioned above, this type of microphone responds to sound velocity rather than pressure. The ribbon in the microphones is very delicate and will break easily if not used properly when exposed to high sound pressure levels.
These mics are mostly found in Studio environments, but it’s worth knowing about them as you never know what you may encounter. Some people have experimented with them for all sorts of live sound use but their delicacy often means they aren’t used.