Specifications

CX335 Technical Manual Page 11
4.07 Understanding Compressor Limiters verses Peak limiting
Due to the range of the ratio control, the compressor can be set up to perform as a very
effective limiter. Further-more, with its soft knee operation, the characteristics of the unit
blend from gentle compression for signal just above threshold, through to hard limiting.
The intelligent control circuitry and programme dependent attack and release make the
audible effect almost un-noticeable. This compressor limiter section should not be
confused with the Peak limiter in the CX335. This is intended to be used as a system
failsafe for any high peaks that are still quite high even after some compression has
occurred.
For example; with signals above the compressor threshold, if the ratio is set to 3:1 and
the input rises by +15dB there will still be a +5dB rise at the output. This rise might cause
a system overload, except this can be trapped by the Limiter section providing the Peak
Limit threshold is correctly adjusted. The optimum use of the Peak Limiter is when used in
this method. It is difficult to give a generalisation for limiter threshold settings as many
factors govern this value:
Firstly, how much level can be sent from the mixing console? In a well configured system
this will average around 0dB, but with only slightly too much gain at each mixing stage
this level can soon rise far higher. The Peak limiter can be set to capture this overload.
Secondly, how much signal is required by the amplifier or crossover inputs? If the Peak
Limiter is set too high then any peaks allowed through the CX335 might cause input
distortion or overload to the following amplifier. It is more likely that the amplifiers will clip
before the output signal clips
4.08 Other nomenclature.
Side-Chain - The control circuit that decides how much gain reduction to apply
at any one instant, depending on the input level and the front panel controls is called the
side-chain. In a standard compressor the circuitry only has two main sections: the audio
path and the side chain.
Gain Reduction - The difference between the measured output level after the
compressor taken effect and the level that would be output if no processing was
happening.
Controls
5.01 Slow switch:
This push switch modifies the programme-dependant circuitry to allow fast dynamic
peaks through unprocessed, yet still monitor and control level when the input is above the
threshold for periods of a second or more. If this switch is depressed it is strongly advised
that the Peak Limiter should be used as an additional trap to capture very loud and quick
dynamic peaks.
5.02 Hard switch:
Modifies the Knee of the compressor by affecting the Ratio control so that gain reduction
takes place linearly once the threshold level is exceeded. It is strongly advised that the
unit be configured in its intended mode of Soft-knee for a more transparent compression.
5.03 Threshold:
Determines the input level above which gain reduction will be applied and may be set in
the range +10dB to -20dB. This control graticule is accurate for compression with the
Hard switch depressed. In the native soft-knee mode, compression takes place gradually
once the threshold is just exceeded. The amount of compression rises, until the input
signal reaches approximately 10dB above the threshold setting, where upon conventional
compression is applied at the amount dictated by the Ratio control.