Chapter 7: Using The Compressor
When LINK is switched on, the compressor sidechains of the linked channels are combined by a true power law summer such that a single source panned from left to right will not change the compression levels that have been applied to it.
Sidechain
For most applications the DN540 is triggered by the level of the incoming signal. Sometimes it can be useful to use a different signal to trigger the compressor; this signal is known as an “external sidechain”.
Each channel of the DN540 has a sidechain input for the compressor. In normal use, the amount of compression or expansion is related to the dynamics of the input signal. The sidechain allows the signal passing through the unit to be controlled by the dynamics of another separate signal.
Particularly in the case of drums, a very reliable trigger can be obtained by taping a contact microphone to the shell of the drum, using the clean signal it produces to trigger the compressor. An example of this set up is shown below.
DN540 (rear panel)
Snare 
Mic
Contact mic
Mic inputs
Send
External | (female | connector) | Output |
sidechain input | (male XLR | ||
(1/4” TRS jack) |
|
| connector) |
| Input | XLR |
|
|
|
| |
Channel insert point (contact mic) |
|
|
|
(snare mic) |
|
|
|
(snare mic) |
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|
|
Send | Return |
Console
Connection to the sidechain input is made via the rear panel jack sockets, see “Connecting the audio cables” on page 10.
| DN540 |
28 | Operator Manual |