MICROPHONE SELF-NOISE EXPLAINED
MICROPHONE SELF-NOISE LEVELS
The electronic circuitry inside a condenser microphone generates background noise. The most commonly used term for it is “self noise” since this signal is produced by the microphone itself even if there is no sound present.
There are lots of ways to measure self-noise. Like many other specifications and the way they’re gathered various manufacturer’s use different techniques to arrive at the numbers provided on the printed specifications they provide through their marketing efforts.
Self-noise is usually specified in dB-A where the A stands for A-weighting which seeks to mimic human sound perception. Without further qualification the specification is like the gas gauge in your car, it gives you an idea about how much gas you have left but it’s not necessarily an exacting measurement between product brands.
HOW MUCH SELF-NOISE IS BAD?
Self-noise below 10 dB-A is very low, below the typical energy present in any normal space so self-noise this low is imperceptible
11-15 dB-A is low, barely detectable, best for classical and critical applications (Neumann TLM-103 listed as 7 dB-A equiv. noise level)
16-19 dB-A is good enough for most recording applications
20-23 dB-A is considered high self-noise level, it’s clearly audible .
24 dB-A and up is considered very-high self noise for studio recording and professional applications though it is not uncommon in SDC type designs.
SELF-NOISE IN DYNAMIC MICROPHONES
Self-noise in dynamic microphones is strongly dependent on the preamp being used with the microphone. If used with very low-noise preampfification the equivalent self-noise would be in the vicinity of 18 dB-A.
SELF NOISE IN LDC vs SDC MICROPHONES
It is easier to make a large diaphragm condenser microphone with very low self noise than it is to make a small diaphragm type. A properly designed LDC microphone will always exhibit lower self noise and makes this type an obvious choice for classical and critical recording applications.