User guide

Other Types of Microphones

For the same ratio of direct/reverberant sound, omni-directional

microphones must be closer to the sound source than cardioid or

bi-directional microphones. Microphones should generally face

the sound source head-on; if not, treble losses due to phase loss

will result. The exception here is for large condenser micro-

phones, which often give the flattest response at an angle of about

10-20 degrees (off axis), where phase loss and diffraction effect

offset each other somewhat.

Proximity Effect and Working Distance

The Sound That Is “More Real than Real”

Ribbon microphones have long been renowned for “rich bass”.

This effect is largely due to the fact that ribbon microphones gen-

erally have excellent bass response to begin with, and at the same

time exhibit an effect known as “proximity effect” or “bass tip-

up”.

As illustrated in the following graph, a typical bi-directional rib-

bon microphone will have a flat frequency response at a distance

of about six feet from the microphone but at shorter distances the

bass response becomes boosted; the effect becomes increasingly

pronounced as the distance between the microphone and the

sound source is reduced.

This bass-boosting characteristic can become quite intense and, if

desired, can be corrected by equalization. However, for a multiple

microphone setup, the pronounced bass boosting (due to prox-

imity effect) can be turned to an advantage. If an instrument,

such as a trumpet, is extremely close-miked and the bass is cut to

restore flat response, unwanted low-frequency sounds are cut

back by upwards of 20 dB compared to an unequalized micro-

phone with a flat response. This discrimination is independent of

the microphone’s polar response.

Typical relationship of microphone distance to frequency response for ribbon-

velocity bi-directional microphone.