Behringer SNR2000 - Manual (Page 21)

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DENOISER SNR2000
The usable dynamic range of electro-acoustic equipment is limited to both the low end and the high end. The
thermal noise of the electrons in the components results in an audible basic noise floor and thus represents the
bottom limit of the transmission range. The upper limit is determined by the levels of the internal operating
voltages; if they are exceeded, audible signal distortion is the result. Although, in theory, the usable dynamic
range is spreading from low to high end, it is considerably smaller in practice, since a certain reserve must be
maintained to avoid distortion of the audio signal if sudden level peaks occur.
Technically speaking, we refer to this reserve as “headroom”—usually about 10 to 20 dB. A reduction of the
operating level would allow for greater headroom, i.e. the risk of signal distortion due to level peaks would be
reduced. However, at the same time, the basic noise floor of the program material would be increased
considerably.
Fig. 4.2: The interactive relationship between operating level and headroom
It is therefore useful to keep the operating level as high as possible without risking signal distortion in order to
achieve optimum transmission quality.
4.2 Compressors/limiters
By measuring the dynamic range of instruments in live recording situations, you will experience that extreme
amplitudes occur which often lead to overload on the various devices in the signal chain. Especially in
broadcasting and record cutting techniques, these signal peaks can lead to heavy distortion. To avoid this kind
of distortion or, for example, to avoid loudspeaker damage, compressors or limiters are used. The basic
function used in these devices is dependent on automatic gain control as mentioned in the previous section,
which reduces the amplitude of loud passages and therefore restricts the original dynamics.
4.3 Expanders/noise gates
Audio, in general, is only as good as the source from which it was derived. The dynamic range of signals will
often be restricted by noise. Synthesizers, effects devices, guitar pickups, amplifiers, etc. generally produce
a high noise level, hum or other ambient background hiss, which can disturb the quality of the program
material.
Normally, these noises are inaudible if the level of the usable signal lies significantly above the level of the
noise. This perception by the ear is based on the “masking” effect: noise will be masked and thus becomes
inaudible as soon as considerably louder sound signals in the same frequency band are added. However, the
further the level of the usable signal decreases, the more the noise floor becomes a disturbing factor.
4. TECHNICAL BACKGROUND