1. POWER Switch:
This switches the AC power ON or OFF.
Note: In order to avoid possible undesired noise transients in a live sound reinforcement application, switch on the power to
your CL-5000 before switching on the amplification system.
Expander/Gate Section (Operation)
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 level of noise, 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 desired signal is significantly above the level of the noise. This perception by the ear is based on the “masking” effect:
noise will be masked and thus become inaudible as soon as considerably louder sound signals in the same frequency band are
added. Conversely, the further the level of the desired signal decreases, the more the noise floor becomes a disturbing factor.
Expanders or noise-gates offer a solution for this problem by attenuating signals when their amplitudes drop, thereby fading out
the background noise. Expanders extend the dynamic range of a signal and are therefore the opposite of compressors.
Expansion over the entire dynamic range is not desirable. For example, with an expansion ratio of 5:1 and a processed dy-
namic range of 30 dB, an output dynamic range of 150 dB would result, exceeding all subsequent signal processors, as well as
human hearing. Therefore the amplitude control is restricted to signals whose levels are below a certain threshold. Signals above
this threshold pass through the unit unchanged. Due to continuous attenuation of the signals below this threshold, this kind of
expansion is termed “downward” expansion.
The noise-gate is the simplest form of an expander. In contrast to an expander, which continuously attenuates a signal below the
threshold, the noise gate cuts off the signal abruptly. In most applications this method is not very useful, since the on/off transi-
tion is too drastic. The onset of a simple gate function appears very obvious and unnatural. To achieve an inaudible processing
of the program material, it is necessary to be able to control the signal’s envelope parameters.
The CL-5000 is equipped with an IRC (Interactive Ratio Control) Expander, so that its expansion ratio is automatically adjusted
dependent on the program material. Critical signals in the vicinity of the threshold level are processed with a minute expansion
ratio, whereas signals that reduce in level will be subjected to an increasingly higher ratio, which will result in greater attenua-
tion. The result is expansion, which is less critical to adjust and more tolerant of useable signals whose level is only slightly above
that of the noise floor. Expansion therefore occurs extremely “soft” with low ratio settings, while the known negative effects of
expansion are inaudible. The Attack time of the IRC expander is set automatically and program-dependent, i.e., extremely short
for quickly changing signals and slower for a more balanced program material. Since the expander/gate adapts itself automati-
cally to the program material, you will note that the IRC circuit produces considerably better results than conventional expanders.
2. THRESHOLD Controls:
Use the THRESHOLD controls to determine the threshold point below which expansion occurs. The range of these controls are
from OFF to +10dB.
3. INAUDIBLE Indicators:
For a signal above the threshold value, the “+” LED lights up. For a signal below the threshold, the “-” LED lights up, indicating
expansion mode.
CONTROLS, CONNECTIONS AND OPERATION
FRONT PANEL
3
9A
8
9B
12 13
1
7
10 11
6
