Manual

2500+ Bus Compressor API
14
based upon those louder low frequencies, resulting in a control voltage that favors the low frequencies
of the signal, causing pumping and a loss of punch. Sometimes, this is not desirable. By engaging the
THRUST
®
switch, this inverse filter is placed in front of the RMS detector, evening out the energy by
lowering the energy in the low frequencies and increasing the energy in the high frequencies, so each
octave has the same energy instead of each octave having half the energy as the one lower. This
creates a unique compression effect that still reduces the overall gain, but the sound is much more
punchy and the signal actually sounds less compressed.
LOUD: A gradual, 10dB/decade filter is applied to the signal feeding the RMS detector, equalizing the
energy going into the RMS detector. This decreases the way lower frequencies act on compression.
The overall difference is a noticeable increase of punch and low frequencies, but a uniformly
compressed signal. It is the “little more punch” function.
• The red LED illuminates when engaged
MED (Medium): A slight attenuation of the low frequencies and a slight boost in the high frequencies,
with a flat mid-range are applied to the signal feeding the RMS detector. This reduces the low
frequencies from pumping the compressor as much and increases the sensitivity of the RMS detector
to the higher frequencies, affecting the higher frequency peaks of the signal.
• The yellow LED illuminates when engaged
NORM (Normal): The THRUST
®
filter is not inserted in the path to the RMS detector and the 2500+
compresses like most units on the market today (the signal in the detection path remains flat).
• The green LED illuminates when engaged
5.1.3 TYPE
The 2500+ can be set to operate in two circuit topologies that determine where the signal that feeds
the RMS detector comes from:
• OLD: Feed-Back topology: The RMS detector receives the signal from after the VCA
• NEW: Feed-Forward topology: The RMS detector receives the signal from before the VCA
The detection path routing is selected using the TYPE switch.
TYPE: Toggle to select detection path routing
• NEW (F FWD): Engages the feed-forward topology
o Yellow LED
• OLD (F BACK): Engages feed-back topology
o Green LED