Cloud CX335 Specifications download pdf (Page 11)

Page 10 CX335 Technical Manual

4.04 Ratio explained.

For a hard-knee compressor, the effect of Ratio can be easily understood by

remembering that ratio is a comparison between input levels and output levels. For

instance; a ratio setting of 3:1 results in only 1dB of change at the output for every rise in

input level by 3dB providing that the input is greater than the threshold setting. A simple

rule of reading Ratio settings can be input:output, or input rise of xdB gives output rise of

ydB. For a soft-knee compressor, the Ratio control becomes a little less well defined

Soft-knee gradually changes the ratio as the signal rises above the threshold setting. On

the CX335 this change takes place for as much as 10dBs, so the selected ratio is only

reached once the signal is 10dB above the threshold setting. This changing ratio is far

more musical and disguises the fact that any manipulation of the dynamic range is taking

place.

4.05 What about Attack and Release controls?

The rate at which the compressor takes effect (once the threshold is exceeded) is called

Attack, similarly the rate at which the compressor subsides (after the input signal falls

below threshold) is called Release. The wrong attack time for a compressor will have

different poor results for differing input frequencies. For instance too fast an attack time

with low frequencies will cause distortion as the gain reduction changes during one cycle,

on the contrary, too slow an attack time on high frequencies will not process the signal

peaks quick enough, resulting in the possibility of system clipping and lack of speaker

protection.

The conclusion is, that for broad-band music programme a fixed attack time is virtually

useless. Similarly a release control that doesn't track the input programme envelope will

result in audible 'pumping' or breathing as the gain reduction changes. The CX335 gets

over this problem by constantly adjusting these two crucial 'parameters' internally

depending on the level and frequency of the incoming signal. For this reason the Attack

and Release controls have been removed from the front panel.

4.06 Gain requirements

When the signal exceeds threshold and the compressor takes effect, there will be a

reduction in the real output 'volume'. This volume reduction is made back-up to the

original level with the Gain control. In normal use, the average amount of level reduction

shown on the gain reduction meter, will be the position to where the Gain control is

rotated positively. A point to note is that this gain is applied to all signals, whether above

or below any thresholds, so quiet sounds will be louder by the amount of gain make-up,

even the residual background system noise!

LIMITING

SOFT KNEE

NO COMPESSION

HARD KNEE

GRAPH OF INPUT LEVEL

VERSES OUTPUT LEVEL

THRESHOLD

OUTPUT IN dBs

INPUT

IN dBs

-10

-5

0dB

+10

-15

-20

-25

-30

-10

-5

0dB

+5 +10

-15-20-25

-30

RATIO 20:1 OR GREATER

RATIO 10:1 OR LESS

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 21 22

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Cloud CX335 Specifications Page 11

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