Microphones convert sound energy to electrical energy, using mechanical motion. How they do this gives us the two main categories of mics – dynamic and condenser mics. This article also looks at how the two differ in their quality and function because of the difference.
Two kinds – Dynamic and Condenser
How does a dynamic microphone work
A dynamic mic has a diaphragm to convert mechanical to electrical energy. The diaphragm is attached to a coil placed in a magnetic field. When hit by sound waves, the diaphragm moves, which in turn moves the attached coil. Moving a metal coil in a magnetic field makes electricity (electric signal). This way sound is converted to electric signal, which we record.
How does a condenser microphone work
A condenser mic has a capacitor or a condenser, (the older name, which is still used for the microphone). A capacitor is an electrical component that stores energy. It has two plates and the energy is stored as electrostatic field between the two plates.
In a condenser microphone one of the plates is light in weight and movable. As sound waves touch the plate, the distance between the plates changes. When the distance between the capacitor leaves changes, a current is formed, which we record.
For a condenser microphone to work, a voltage is required across the leaves. That is why we need a phantom power supply or battery power to use a condenser microphone.
Using Condenser (capacitor) microphone
Fast response of condenser mics
Condenser leaf moves much easier on facing a sound wave than a heavier diaphragm in a dynamic mic. So condenser mics are very good at recording to nuances, detailed changes over very short time periods, when compared to a dynamic microphone, whose diaphragm has inertia and hence does not move so easily.
So we can use condenser microphones for vocals and other instruments where the nuances and fast response matters.
Capacitor mics record the frequencies very well, producing a more open sound with much more clarity and definition than a dynamic mic. Dynamic mics are not very good with recording high frequencies. So to record instrument whose high frequencies are important (high hats, cymbals), and where clarity is needed (lead vocals), using condenser mic has its advantages.
Condenser mics need very less equalizing
Since condenser mics are good at picking up the sound without losing much frequencies, condenser mics need very less eqing.
Considering that any processing, eqing included, degrades the signal, using condenser mic has the advantage that we record the signal as close as possible to the final result we want in the mix.
I use aRode NTK Tube Condenser Microphone. The only eqing I do is to cut away some frequency at around 10kHz, and the unnecessary bass part below 100Hz (slow slope to zero)
Condenser mics need less preamp gain
Capacitor or condenser mic is more sensitive than a dynamic mic and therefore needs less preamp gain.
A few more things about condenser mics
Condenser microphones are not suitable for loud sources since it distorts owing to its sensitivity.
A condenser mic will pick up sounds from the surroundings much more than a dynamic. This is one reason using a condenser mic for vocals on stage can be difficult. The vocal condenser mic will pick up all the other sounds as well, much more than a Shure SM58 – a cardioid, directional, dynamic microphone.
With a condenser mic you will have to use a pop filter, since syllables like b, p, f, etc will cause a wind blast into the mic.
A condenser mic recording benefits from using a shock mount when attaching the mic to the stand.
Dynamic Microphone for vocals
Shure SM58 – probably the most popular mic – widely used for onstage performances.
Its main advantages is that it is affordable within the most basic budgets (less than Rs.5000 new).
SM58 is easy to handle.
Its cardioid pattern and directional nature helps record the vocals with least bleed from the surroundings.
To make a SM58 vocal recording to sit well in a mix, Eqing, compression, reverb, delay and panning techniques are used.
Condensers are superior to dynamic mics for their sensitivity, especially high frequencies. Recordings through a condenser mic represent the original sound very well with the need for EQing kept at a minimum.
Rode NTK Tube Condenser Microphone is a good large diaphragm condenser mic in the budget range. Audio Technica has some good affordable large diaphragm condenser mics too. Audio Technica AT4040 and Audio Technica AT4050 Condenser Microphone are two examples.
A large diaphragm condenser mic like RODE NTK records the sound better than a dynamic mic like SM58.
But an SM58 is still useful because it is more affordable, easy to handle and picks up the surroundings less. For stage performances SM58 is still preferred.