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of punch. Sometimes, this is not desirable. By switching the
LOUD positions, 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 much less compressed.
The L/R LINK feature is also unique to the API 2500. First, there is a variable link control, ranging
from IND (independent) to 50% through 100% in six steps. Variable linking allows combining of the
Left/Right control voltages over a range, minimizing the interaction between channels, while still
linking them to retain the stereo image. While engaged, the link control has selectable detection
speeds, FAST (peak) and SLOW (RMS).
compressor circuits, from the input through the RMS detector, the VCA's and to the output section.
When many compressors are linked to the "STEREO LINK" mode, only one channel is controlling the
compression. When the 50th Anniversary 2500 is linked, the control voltages are summed together,
but both channels are still detecting their own control voltages. This also eliminates changing of the
tone of the compressor when linking is used.
Additionally, each channel uses multiple VCA's to minimize noise and distortion found in single VCA
compressors. The input and output stages are ALL DISCRETE, using the API 2510 and the API 2520
op amps.
A TYPE switch that lets you choose between classic and modern compression characteristics: OLD for
vintage-style feedback compression and NEW for today's more common feed-forward compression.
The 3-position KNEE switch adjusts the shape of the curve at the onset of compression for an "over-
easy" type compression resulting in a very natural, uncompressed sound or a typical sharp knee type
that lends itself to a much more severe limiting effect.
The auto make-up GAIN function lets you adjust ratio and threshold controls without affecting the
output level. Alternately, make-up GAIN can be set manually.
BLEND is a new feature that allows mixed or parallel compression to be achieved on-board by allowing
the input and compressed signals to be "blended" in two different ways: input vs. compressed dry/wet
percentage (Crossfade) or input plus compressed percentage (Parallel).
2.0 Quick Start
One tip to get started: We try to design all of our processing modules with the understanding that
there is never enough time to read a manual and learn all of the features in the 10 seconds that is
allowed during a setup. If you simply set all of the parameters as follows the 50th Anniversary 2500
will have a useful, but conservative effect on the signal.
•
Set all of the knobs in the COMPRESSOR section to the 12:00 position
•
Set KNEE to MED
THRUST
•
Set
•
Set TYPE to NEW
•
Set L/R LINK to 50%
•
Set SHAPE to SLOW
•
Turn off MANUAL make-up gain (auto make-up gain on)
•
Set BLEND to off:
These settings will provide a good starting place for additional tweaking to achieve the desired sound.
50
th
Anniversary 2500 Bus Compressor
®
to NORM
X
(Crossfade) or
THRUST
The 50th Anniversary 2500 has two complete, identical
Many popular units actually change when linked!
l l
(Parallel) not engaged
7
®
button in either the MED or
API
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