5
Example: if a microphone has an equivalent noise level (self-noise) 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 .
A low noise level helps to keep the signal clean when recording quiet sources!
The range between the equivalent noise level and the maximum sound pressure
level is referred to as the dynamic range of a microphone .
Spoken in practical terms, low self-noise does not limit your freedom of
microphone positioning . With noisy microphones, you need to get very close to
the recorded sound source to get a good signal-to-noise ratio . A low self-noise
microphone, on the other hand, can record not only distant but also very quiet
sound sources . With its 7 dB (A) of equivalent noise level it is guaranteed that
your studio microphone is never the cause of noise problems .
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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 section
9 Tech graph for the frequency response chart .
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MAX SPL
LCT 440 PURE - Max . SPL for 0 .5 % THD: 140 dBSPL
Manufacturers state the maximum sound pressure level a microphone can
handle before the signal starts to distort . In sound reproduction, 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
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Sensitivity
LCT 440 PURE - Sensitivity: 27 .4 mV/Pa, -31 .2 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 .
“27 .4 mV/Pa” means, the microphone produces an output signal of 27 .4 mV
when it is being exposed to 1 Pascal (1Pa = 94 dB SPL) . “-31 .2 dBV/Pa“ means,
the microphone produces an output signal of -32 .7 dBV when it is being exposed
to 1 Pascal (1Pa = 94 dB SPL) . This value is more practical, as dB values are easily
comparable .
LCT 440 PURE: -31 .2 dBV/Pa .
Microphone X: -51 .2 dBV/Pa . Microphone X would need an extra gain of 20 dB to
produce the same output level as the LCT 440 PURE .
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Equivalent noise level or self-noise
LCT440 PURE - Equivalent noise level: 7 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 . In other
words, there is a sound pressure level that matches the inherent self-noise of the
microphone . This sound pressure level is the equivalent noise level (self-noise) of
the microphone .
