User guide

Radial Engineering Ltd.
PreComp™ Preamp and VCA Compressor
True to the Music
®
5
ADDING COMPRESSION
From the starting position, as described on page four, activate the compressor by depressing the
IN switch. There should be little or no difference in the sound with these settings.
Threshold: This control is used to set the signal level where compression will occur. The
middle and bottom LEDs on the three stage meter are used to help set the threshold level. The
bottom green LED illuminates when the signal is below the set threshold and no compression
is occurring. The middle yellow LED illuminates when the signal crosses above the threshold
and indicates the compressor is working.
THRESHOLD LEVEL
+10dB -
0dB -
-10dB -
+10dB -
0dB -
-10dB -
ABOVE
BELOW
THRSH
-20
-10
+10
0dB
ABOVE
BELOW
THRSH
-20
-10
+10
0dB
THRESHOLD LEVEL
When the input signal is below the threshold
level the green LED indicator illuminates.
When the input signal is above the threshold
level the yellow LED indicator illuminates.
Speak into the mic and turn the threshold control counter clockwise until the center yellow
LED starts to fl ash. Lowering the threshold further will compress most of the audio signal
and severely reduce the dynamic range. Raising the threshold leaves most of the dynamics
unchanged and only compresses the loudest peaks.
Ratio: The ratio control is used to set the amount
of gain reduction applied when the signal goes
over the threshold setting. For each decibel the
signal rises above the threshold the compressor
reduces the output by the ratio factor. For
instance, with a ratio setting of 4:1 a 4dB signal
peak above the threshold will produce a 1dB
increase at the output. The table below outlines
the general effect of different compression ratios
and examples of their use.
1.2:1 2:1 5:1 10:1
Slight Moderate Signifi cant Heavy
Mostly unnoticed Smooth dynamics Controlled dynamics No dynamics
Used for master bus
compression and music
Used to smooth out
vocals and instruments
Used for instruments
with wide dynamics
Highly compressed with
narrow or no dynamics
Music program playback Ballad vocals & strings Slap bass & percussion Sound effects, Announce
Set the control to a moderate ratio of 2:1 and speak into the mic. Each time the yellow threshold
LED lights the output is compressed. If the yellow threshold LED is not fl ashing on the signal
peaks, turn the threshold level down until it does. Now increase the ratio control to 5:1 and then
10:1 and observe how the dynamic range is reduced at each setting.