User's Manual
5
In other words, there is a sound pressure level that matches the inherent noise of
the microphone. This sound pressure level is the equivalent noise level (self-noise)
of a microphone.
Example: if a microphone has a self-noise value of 10 dB (A) SPL and picks up
a sound source with 10 dB (A) SPL the signal to noise ratio is 1:1 or 50/50.
// Frequency response
The frequency response shows the sensitivity over the microphone’s frequency
spectrum and has a huge inuence on the “sound” of a microphone. See tech
graph section for the frequency response chart.
// MAX SPL
LCT 240 PRO - Max. SPL for 0.5 % THD: 142 dBSPL
Manufacturers state the maximum sound pressure level a microphone can handle
before the signal starts to distort. In sound recording, we often aim for a “pure”,
undistorted signal. When distortion becomes audible, depends on the source
material and the listener‘s perception. Most manufacturers state the MAX SPL at
0.5% THD (Total Harmonic Distortion), measured at 1kHz.
4.4. Important specs of a condenser microphone
// Sensitivity
LCT 240 PRO - Sensitivity: 16.7 mV/Pa, -35.5 dBV/Pa
You can often read that a condenser microphone has a “high” sensitivity. What
does that mean in practical terms? In short, it means that a more sensitive
microphone is “hotter” – i.e. it requires less gain (amplication) to achieve
a certain output level. You can specify a microphone’s sensitivity in two ways:
in mV/Pa or dBV/Pa.
“16.7 mV/Pa” means, the microphone produces an output signal of 16.7 mV
when it is being exposed to 1 Pascal (1Pa = 94 dB SPL). “-35.5 dBV/Pa“ means,
the microphone produces an output signal of -35.5 dBV when it is being exposed
to 1 Pascal (1Pa = 94 dB SPL). This value is practical, as dB values are easily
comparable.
LCT 240 PRO: -35.5 dBV/Pa.
Microphone X: -55.5 dBV/Pa.
Microphone X would need an extra gain of 20 dB to produce the same output
level as the LCT 240 PRO.
// Equivalent noise level or self-noise
LCT 240 PRO - Equivalent noise level: 19 dB (A)
Self-noise or, more accurately, equivalent noise level is the sound pressure level
that is equal to the RMS voltage that can be measured at the output connector of
a microphone without an external sound source being recorded.