Behringer SNR2000 - Manual (Page 14)

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DENOISER SNR2000
2.4.1 THRESHOLD control
The THRESHOLD control of the expander defines the operating level. It stretches across a very wide range and
therefore applies to all working levels. Input levels above the adjusted threshold point do not experience any
change. However, if the level falls below the threshold the dynamic process is active.
For example, if the THRESHOLD control was set at 0 dBu and the input signal drops below 0 dBu, downward
expansion will begin. In typical applications the setting of the threshold control should be between 5 and 20 dB
above the quiescent noise floor of the input signal. For example, if the quiescent noise floor was
-40 dBu, a setting between -35 to -20 dBu will produce the desired expansion.
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With the RATIO control set to maximum and the THRESHOLD control set at +10 dBu, an input
signal level would have to exceed approximately +5 dBu to produce an output signal.
2.4.2 RELEASE control
The RELEASE control determines the time the downward expander requires to decrease the level of the
output signal. The RELEASE control is variable from 0.2 to 4 seconds and refers to a 20 dB gain change. The
ultimate setting of the RELEASE control depends on your demands: When the expander sections are
supposed to function as gates, settings between 0.2 and 0.5 seconds are recommended.
For individual instruments or vocals use a setting between 0.2 and 0.5 seconds. For composite music a
setting between 0.6 and 2 seconds is recommended. If you want to use the expander section to reduce subtle
background noise from effects devices, a very slow release time (2 to 6 seconds) would be perfect.
2.4.3 RATIO control
The ratio between input and output level for all signals that fall below the threshold is called expansion
ratio. It is adjustable via the RATIO control. This control adjusts an important parameter: It determines whether
the section functions as expander or gate.
A ratio of 1:1 indicates that the output signal will correspond to the input signal, i.e. the level does not change.
A ratio of 1:2 indicates that for every 1 dB decrease in input level below the threshold, there will be resultant
corresponding decrease in the output level of 2 dB. A ratio of 1:6 indicates, that for a 1 dB decrease in input
level below the threshold, there will be a corresponding decrease in the output level of 6 dB etc.
Low ratios from 1:1 to about 1:3 produce precisely controlled downward expansion. At more pronounced
settings up to 1:6 the DENOISER functions as gate.
The scale of the ratio is calibrated in dB on the front panel. It indicates the decrease in output level, resulting
from a 1 dB decrease in input level.
The DENOISER works as an IRC expander. The interactive control function defines the soft onset of the
expander, according to the characteristics of human hearing during the fade out process. This allows for a
natural and thus inaudible elimination of interference noise. This means that, as the input level drops slightly
below the threshold point, the expander ratio will start at 1.1:1 and increase to an ultimate ratio selected with
the RATIO control. The correct setting of the ratio control depends on your demands: In order to achieve a
flat expansion curve, we recommend settings of 1:1 to 1:3. This provides soft and limited expansion for
difficult and noisy audio applications. Higher settings up to 1:6 are recommended for gating applications
which allow for noise reduction of more than 70 dB.
2.4.4 GAIN REDUCTION meter
The eight GAIN REDUCTION LEDs on the front panel of the BEHRINGER DENOISER function as follows:
If the input level falls below the threshold, the expander starts working with the current level reduction factor
being indicated by the GAIN REDUCTION LEDs.
Let us consider, for example, a specific signal that falls by 2 dB below the threshold: with a ratio setting of
1:6, the output signal is attenuated by 12 dB; in comparison to the input signal the output signal has been
reduced by 12 dB, which is indicated by the 10 dB LED.
Although the VCA of the BEHRINGER DENOISER provides a control range of 80 dB, it is not very useful to
display the entire range, since such drastic control processes are performed very rarely in practice. The
displayed range of the GAIN REDUCTION indicators is 40 dB.
2. OPERATION