API 2500 Manual page 8

Link and
Output
Section
L/R LINK:
This control sets the left to right LINK percentage. Most compressors only allow
100% linking between channels. The 2500 allows for linking starting at IND,
which is 0% and 50% to 100% in six additional steps. At the same time, each
channel is still controlled by its own detector, preventing loading and slaving
from one side, which many times creates errors. This control mixed each
channel's RMS detector controls together according to the switch position.
SHAPE:
This control adjusts the SHAPE of the LINK control voltage mixing. There are two
filters, a high pass filter, eliminating the lows, a low pass filter, eliminating the
highs and a combination of both filters creating a band pass filter. The value of
this circuit allows the LINK control voltage to NOT include certain frequencies,
such as the low frequency end of each channel, preventing the low frequencies
from linking from the left side to the right side, etc. When the different
combinations of the filters are used, sounds like sharp percussive instruments
on one channel will not couple to the other channel and cause it to compress.
IN and BYPASS:
The IN switch is a soft IN/OUT button that defeats the compression action
silently, but allows the signal to pass through the 2500.
The BYP switch is a relay hard-wire bypass that routes the signal directly from
the input XLR to the output XLR, without going through any electronics. If the
power fails to the 2500, the BYP automatically engages, preventing any loss of
signal during the power fault.
GAIN:
When the GAIN switch is pressed IN, the GAIN pot controls the amount of make-
up gain added to maintain the desired overall gain after the compression action
reduces the output level. When in the OUT position, the output make-up gain is
automatically set as a result of the position of the THRESH or RATIO controls. If
the input signal is below +4 dBu, rotating the THRESH control will increase the
output level until the output level is around +4 dBu, and then as the signal gets
compressed, it will maintain an even output level, allowing THRESH and RATIO
adjustments without having to re-adjust the make-up gain. This is very useful
during situations where an adjustment needs to be made without disturbing the
output level to tape or air. This function is similar to the API 525 ceiling control.
LINK
70
HP
60
80 BP
50 90
LP
100
IND
percent filter
L/R LINK
SHAPE
OUTPUT
9
6
man
3
0
+24
make-up dB
IN GAIN GAIN
BYP
12
18