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Since condenser microphones incorporate a preamplifier, they introduce a low amount of self-noise which appears at the microphone output as an unwanted signal voltage. This noise voltage is measured using standard weighting filters and the result stated as the equivalent noise level in dB. An equivalent noise level of 20 dB, for instance, means that the self-noise of the microphone is as loud as a sound at 20 dB SPL (see dB SPL). Noise level in quiet recording studio A low equivalent noise level means that the microphone's self-noise is low. The self-noise voltage is weighted either conforming to IEC 268-1 and DIN 45 405 using the filter according to CCIR 468-3 with the "quasi-peak" value being quoted, or in accordance with IEC 651 or DIN 45 412 using the A-weighting curve with the rms value being quoted. Studio engineers seem to prefer the CCIR weighting while A-weighting is still accepted as well. |