Setting the Controls
If you are starting from scratch or have something out of whack and do not know exactly what to adjust‚ begin by setting the controls so that all functions are disabled. Here are the control positions for this:
Expander | |
Threshold | min (off ) |
Ratio | min (1:1) |
Compressor | |
Threshold | max (+20 dB) |
Ratio | min (1:1) |
Attack | center (50 mSec) |
Release | center (.5 sec) |
Limit | max (off ) |
Gain | min (0 dB) |
Low Cut | out (off ) |
De-ess | out (off ) |
| |
Naturally‚ the controls that need to be adjusted depend on what you want to accomplish. Below are some suggestions to get you up and running. Follow the order listed and leave the controls in the disabled positions if that particular function is not required.
1.Determine the maximum output level and adjust the Limit Threshold so that‚ at the loudest peaks‚ the output level never exceeds this point. (The action of the limiter can be seen on the Gain Reduction Meter. If it never activates‚ there will be no LED activity.) One way to do this is to deliberately increase the input to the compressor until the desired maximum level is exceeded‚ then turn the Limit Threshold control counter-clockwise until it limits it to the correct gain. Reset the input level to the nominal setting (0 dBu average). An alternate method is to turn down the Limit Threshold until gain reduction has just occurred. Then‚ adjust the output level control to set the desired output level. If the limit is set too low‚ the signal will lose its dynamic range and the sound will be squashed.
2.To set up a noise gate‚ first turn the Expander Ratio control fully clockwise (1:5). During quiet passages of the source (between songs‚ when the mics are not being used‚ etc.) adjust the Expander Threshold clockwise until gain reduction is indicated (a reduction of -9 dB is a good starting point). Re-adjust the Expander Ratio to set the desired gating action when the source changes from noise to signal. A setting of 1:1.2 has little action and can tolerate higher threshold settings without coloring the sound; 1:5 will cause an abrupt turn on and off when the signal changes and will probably need a lower threshold setting to prevent the signal from dropping off when you don’t want it to. You may need to go back and adjust the threshold after the ratio has been changed since the soft-knee circuitry has more affect at lower ratios‚ making the transition point less obvious.
3.For typical voice compression‚ set the Compressor Ratio control to 4:1 (a range of 2:1 to 6:1 is common) and adjust the Compressor Threshold until the desired amount of gain reduction is seen on the meter. This is a personal preference but continuous gain reduction greater than -9 dB (especially with higher ratios) could be excessive and create pumping/breathing artifacts as the signal rises and falls. Lower ratios will have a more gentle affect. Adjust the Attack control to low values to suppress leading-edge spikes or to high values to let them through (often used to pass through the click of a drum hit). The Release control is adjusted to smooth the transition as it comes out of compression. Too quick a release will cause the signal to sound artificial. A fast attack and a short release time will cause the compressor to track the signal very closely (and keep the dynamic range very limited)‚ but can severely impact the sound. (A 50 millisecond attack and a .5 second release time are good starting points.)
