Operation Manual

30 Parameters

Tuning

The level at which the Compressor starts to enter into action is determined by the value of the

Threshold parameter. This value is in dB and corresponds to the amplitude of the input signal as

monitored by the ﬁrst level meter of the module.

The amount of compression applied to the part of the signal exceeding the threshold value

depends on the Ratio parameter which varies between value of 1:1 and 1:16. This parameter

represents the ratio, in dB, between the portion of the output signal from the compressor above

the threshold value and the portion of its input signal also exceeding the threshold value. As one

might expect, increasing the ratio also increases the amount of compression applied to the signal.

For example, a ratio of 1:5 means that if the input signal exceeds the threshold by 5 dB, the output

signal will exceed the threshold by only 1 dB. Note that the Ratio parameter can also be adjusted

from the Play view.

Two other controls affect the behavior of the Compressor. The Attack knob is used to set the

time, in milliseconds, before the Compressor fully kicks in after the level of the input has exceeded

the threshold value. A short value means that the compressor will reach the amount of compression

as set by the Ratio knob rapidly. With a longer attack, this amount will be reached more gradually.

In other words, the attack time is a measure of the attack transient time of the compression effect.

The Release parameter is similar and represents the amount of time taken by the Compressor to

stop compressing once the amplitude of the input signal falls below the threshold value.

The Makeup knob is used to adjust the overall level at the output of the Compressor module

and is used to compensate from an overall change in signal level due to the compression effect.

The location of the Compressor in the signal path depends on the setting of the Pre button.

When this knob is on, the Compressor is located at the output from the piano, just before the EQ

module. In this position, the input signal of the Compressor and its control signal are both the

output signal from the piano. When the Pre button is off, the Compressor is located after the EQ

module. In this conﬁguration, the control signal of the Compressor is then the output signal from

the EQ module. The input signal to the compressor is determined by the position of the SC button.

When it is on, the Compressor is in a side-chain conﬁguration. The input of the Compressor is

then the output signal from the piano. When it is off, the input of the Compressor is the output

signal from the EQ module.

Using the compressor in side chain conﬁguration is useful when one wants to trigger the com-

pressor using other criteria than the general level of the signal to be compressed. For example, a

sound with a lot of bass would easily trigger the Compressor when playing low notes. In order

to avoid that, the EQ module would be set to ﬁlter out low frequency components. This signal

would then be used to control the Compressor while the input signal to the Compressor would

still include these low frequency components.

The attenuation or gain reduction level meter, located in the middle of the module, indicates

the amount of compression applied by the module. It is the difference between the input and output

signals of the module before makeup gain is applied.