Lewitt LCT 240 PRO, User Manual

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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 influence 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 (amplification) 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 .