Microphones

The directional response of microphones is an important consideration during sound recording. The directional response varies greatly will angle of incidence for high frequencies. Consider high and low frequency waves incident on a microphone diaphragm shown. At an steep angle of incidence there are proportionality less nodes and antinodes over the same surface area, hence a much reduced response. At low frequencies the effect is much less significant and the microphone can be though of as omni directional.

Cardioids are also the preferred mic to use on stage for sound reinforcement applications, since they are less likely to feedback through a PA system. On the downside, cardioids are more susceptible to handling and wind noise, so if you can't secure your mics firmly or have to record in windy situations and don't want to use large windscreens, omni-directionals would be a better choice.

(above diff types of mics - expand a lot)

Transient Response

Transient response is a measure of how quickly a microphone's diaphram can respond to changes in waveform. This can lead to wide differences in the resulting sound between microphones, particularly when used with percussive sounds.

Condenser Microphones

A condenser microphone is essentially a capacitor, with one plate of the capacitor moving in response to sound waves. The movement changes the capacitance of the capacitor, and these changes are amplified to create a measurable signal. Condenser microphones usually need a small battery to provide a voltage across the capacitor.

Advantages:

* Best overall frequency response makes this the microphone of choice for many recording applications.

Disadvantages:

* Expensive

* May pop and crack when close miked

* Requires a battery or external power supply to bias the plates.

Frequency Response

The frequency response of a microphone is the characteristic graph obtained by recording the voltage output level in dB, while the microphone is exposed to a range (sweep) of pure sinusoidal tones of equal intensity. The frequency response is often given as a graph or stated as variation within a given range, e.g.

Frequency response ±3dB from 20Hz - 20kHz

The frequency response gives important information about the tonal balance of the microphone under different acoustic conditions. For high quality instrument grade microphones a large flat range (20Hz to 20KHz) is required. However different microphones exist for different types of application. For example when recording vocals a presence boost around 2kHz to 5kHz improves diction and intelligibility. Many celebrated studio microphones are chosen for their own distinctive warmth and clarity in much the same way as musical instruments.