PreSonus VXP - Manual (Page 20)

CONTROLS & CONNECTIONS
18
An Expander is a processing device used to increase the dynamic range of
the signal being processed through it or in the case of down ward
expansion, as in the VXP, to decrease the signal. Expanders can make
quiet sounds quieter and loud sounds louder. Downward expansion
provides a hybrid result, i.e., signals above the Threshold are untouched
while those below the Threshold are attenuated at a ratio set by the Ratio
control. In this application, downward expansion is used for noise
reduction. Setting the Threshold level to just below quietest vocal level and
adjusting the Ratio to 3:1 will cause the Expander to decrease the signal
below the point set by the threshold as soon as the vocal signal stops. This
level decrease will occur at the rate set by the ratio setting, in this case 3:1,
effectively eliminating any unwanted noise from coming through. The
resulting decrease in signal would be down to –30dB if the VXP
Expander’s Threshold had been set to –10 dB. The VXP’s Expander is
designed to operate below the selected Threshold at the amount determined
by the ratio setting selected. If the quietest signal was –10 dB as in the
example, then the decrease that automatically occurs with the –10 dB
threshold setting would be-30 dB at a ratio of 3:1.
2 . 5 D E - E S S E R
A de-esser is a special type of compressor designed to operate only at
predetermined frequencies to reduce the effect of vocal sibilant sounds such
as S’s at the beginning and ending of words, for example. The VXP De-
Esser has a variable threshold range from –40 dB to +20 dB. The
frequency of operation is determined by selecting the most effective
frequency with the Frequency Range controller. It has a range from 800Hz
to 8kHz. Annoying “S” sounds can be completely removed leaving the
desired signal intact with the proper adjustment of the frequency and
threshold controls. The 4 segment LED shows the gain reduction occurring
due to the De-Esser functioning.