The Compressor - Novation X-Station User Manual

DETAILED OPERATION
The Mod Centre function moves the middle point between the Min and
Max values. Turn the BOTTOM LINE knob to experiment with this con-
trol for the desired effect.
Press the BANK PAGE Up button and a final Menu display page
appears as below :
Feedback :
Feedback
This function controls how much of the delayed signal is fed back to the
input of the Chorus generator. The Chorus effect benefits from low lev-
els of feedback. When acting as a Phaser (see the Chorus Type setting
on Page 22), the effect often requires higher levels of feedback. Turn
the TOP LINE knob to experiment with this control for the desired
effect.

The Compressor

In music, it is the dynamic performance that will captivate the audience.
Although this is good for the listener it is often difficult for the recording
engineer and the associated recording equipment the keep the wide
range of signal levels resulting for the dynamic performance 'under con-
trol'.
'Under control' means that the peak levels must reduced to prevent
overload and subsequent distortion.
The Compressor provides this control, it simply reduces the difference
between the loudest and quietest parts of the input signal by automati-
cally turning down the gain when the signal gets past a predetermined
level.
In order get the compressor to behave in the correct manner for differ-
ent input signal conditions (the settings when recording a vocalist may
be quite different from those required for a Guitar solo), various controls
are provided.
These are: Compression Ratio, Threshold, Attack, Release, Auto gain
and Hold controls. To adjust the controls for the Compressor use the
UP and DOWN arrow until the Compressor LED next the Compressor
label is selected.
Compression Ratio
When the input signal exceeds a 'Threshold' (see next page for setting
of the Threshold level) the compressor reduces the level of the input
signal. The actual amount of this level reduction depends on the
'Compression Ratio' setting.
The LEVEL knob adjusts the 'Compression Ratio' and this is displayed
as shown in the illustration below.
Compress Ratio dB:
Turning the knob will set ratios from 1.0 to 13.7 in steps of 0.1 dB. For
example, if this is set to Ratio 2.0, any part of the input signal that
exceeds the 'Threshold Level' will be attenuated by a factor of 2 to 1.
This naturally has the effect of making any peaks in the incoming signal
sound less loud.
The effect of 'taming down' the loudest parts of the signal will be
increased as the Ratio is increased. A setting of 1.0 will have no effect
on the input signal.
Threshold
Adjusting the TOP LINE knob will set the 'Threshold' signal level where
the compression takes effect. If the whole of the input signal is to be
-64
compressed then setting this to -60dB will result in all signal levels from
the quietest (-60dB or less) to the loudest ( 0dB) to be compressed by
the ratio set by the level control.
If compression is not required, then setting a maximum threshold of
0dB will have the effect of raising the threshold so high that even the
loudest signal will not trigger the compression effect. A typical useful
setting would be -20dB since the compression effect would only be trig-
gered by fairly loud signals.
If either the TOP LINE, or BOTTOM LINE knob is adjusted the display
will alter to display the Threshold and Auto Gain settings below.
Auto Gain
To ensure that the audio signal remains at a reasonably high level and
does not become noisy an Auto Gain setting is provided.
Supposing that all signals above -20dB are being compressed at the
rate of 2 : 0. If much of the input signal is above this threshold then the
resultant signal level output would naturally become quieter overall.
The Auto Gain control is used to get the overall sound level back to a
reasonable level.
A setting of 0 would result in no Auto Gain control. The effect would be
as described above whereby the overall signal would get quieter as a
lower threshold level is set or if a higher compression ratio is set.
Higher settings will restore the signal to a reasonable level. A maximum
setting of 127 will cause the Auto Gain control to return the signal to the
same loudness even with high compression ratios and low thresholds.
To access the remaining controls of the Compressor, press the MENU
button. The BANK PAGE UP/DOWN buttons may now be used to scroll
forwards and backwards through any additional Menu screens.
Attack Time
The compressor needs to know how quickly to apply the compression
ratio once the threshold level has been exceeded.
Turning the TOP LINE knob adjusts the Attack time from 0.1mS to
200mS. If the Attack time is set to a low value (Fastest Attack time)
then the compression effect will be instantaneous.
2.0
Setting to a longer time will result in the input signal passing through
unchanged for a longer time before being compressed.
Very often when recording percussive instruments such as Drums and
Guitars, setting the attack time to a medium setting (say 20-40) will
enhance the characteristics of the instrument since the transient portion
at the start of the Drum beat or Guitar pluck will remain unchanged.
This has the effect of making the sound more 'punchy'.
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25
The Compressor
Threshold dB: -20
Auto Gain dB: 64
Attack : 20
Release : 65