User`s manual

10
4.2.2 Ratio control
4.2.3 Attack control
Output
Threshold
Gain 0 dB
Ratio 2:1
Ratio 4:1
Limiter :1
Input
Chart.5: Ratio control characteristic of the compressor section
4.2.4 Release control
4.2.5 Auto switch
4.2.6 Output control
4.2.7 Effect switch
This control sets the change of input level to output level but only for the signals that exceed the threshold.
The scale of the ratio control on the front panel (calibrated in dB) indicates how much input level is required
to increase the output level by 1dB. If you have a ratio equal to 1:1 you will get the same level of input and
output signal: So, no level change.
If you have a ratio of 2:1 this means that for every 2dB increase of the input level (above threshold) you will
get an increase of output level of 1dB. On the same way, a ratio of 10:1 means that for every 10dB increase
of the input level (above threshold) you will get an increase in output level equal to 1dB, and so on.You need
to be aware that higher ratio settings produce less natural sounds so if you wish a more minute effect on the
dynamic range of a program you should use a ratio of 4:1 or lower.
The attack time represents the amount of time that passes before the compressor start to lower the output
level when the signal is above the threshold point.
For very fast transients such as drums, handclaps, etc, a short attack time will be used. These peaks are
consequently carefully regulated by the compressor. Sounds of other nature will get advantages if longer
attack times are used. Anyway, our advice is always to begin the process with longer attack times. Then you
can start gradually to reduce the attack time. In the ACL2 the attack time can be set in a range of 1 to 200
milliseconds.
This control determines how much time the compressor needs to get back to normal gain when the audio
signal falls below the set threshold.
A too short release time will make the volume to fluctuate and you will experience pumping effect. A too long
release time will give you pumping and breathing effect especially when you have loud passage followed by
a quite passage. The release time on ACL2 can be set from 0.05 to 4 seconds.
This switch turns off the possibility of manually set the attack and release time. An intelligent program re-
cognition circuit will automatically set the attack and release time. In such way, undesirable effects such as
distortion and pumping will be avoided.
This control is indispensable to compensate the loss of level at output level generated by the gain reduction
caused by the compression and limiting processing
This switch simply turns off the correspondent channel. This is useful to compare quickly the processed and
unprocessed signal.