Specifications

Audio Plug-Ins Guide42
BF-2A Controls
The Peak Reduction and Gain controls combine
with the Comp/Limit switch to determine the
amount and sound of the compression. The fol-
lowing controls and meters are provided:
Gain Gain provides makeup gain to bring the
signal back after passing through peak reduc-
tion.
Peak Reduction Peak Reduction controls the
amount of signal entering the side-chain, which
in turn affects the amount of compression and
the threshold. The more Peak Reduction you
dial in, the more “squashed” the sound. Too lit-
tle peak reduction and you will not hear any
compression action; too much and the sound be-
comes muffled and dead sounding.
Comp/Lim The Comp/Limit switch affects the
compression ratio. The common setting for au-
dio production is Comp, which provides a max-
imum compression ratio of approximately 3:1.
In Limit mode, the unit behaves more like a
broadcast limiter, with a higher threshold and
compression ratio of approximately 12:1.
Meter Both Gain Reduction and Output meter-
ing are provided. The Meter knob operates as
follows:
• When set to Gain Reduction, the meter nee-
dle moves backward from 0 to show the
amount of compression being applied to the
signal in dB.
• Whe set to Output, the needle indicates the
output level of the signal. The meter is cal-
ibrated with 0 VU indicating –18 dBFS.
Using the BF-2A Side-Chain
Filter
The BF-2A provides an extra parameter, a side-
chain filter, that does not have a control on the
plug-in interface, but that can be accessed on-
screen through Pro Tools automation controls.
In addition, the side-chain filter can be adjusted
directly from any supported control surface.
This side-chain filter reproduces the effect of an
adjustable resistor on the back panel of the
LA-2A. This control cuts the low frequencies
from the side-chain, or control signal, that de-
termines the amount of gain reduction applied
by the compressor.
By increasing the value of the side-chain filter,
you filter out frequencies below 250 Hz from the
control signal, and decrease their effect on gain
reduction.
 A setting of zero means that the filter is not
applied to the side chain signal.
 A setting of 100 means that all frequencies be-
low 250 Hz are filtered out of the side chain sig-
nal.
To access the side-chain filter on-screen:
1 Click the Plug-In Automation button in the
Plug-In window to open the Automation Enable
window.
2 In the list of controls at the left, click to select
Side-Chain Filter and click
Add (or, just double-
click the desired control in the list).
3 Click OK to close the plug-in automation win-
dow.