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 determines 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 below 250 Hz are filtered out of the side chain signal.

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 window.

4 In the Edit window, do one of the following:

Click the Track View selector and select Side-Chain Filter from the BF-2A sub-menu.

– or – 

Reveal an Automation lane for the track, click the Automation Type selector and select Side-Chain Filter from the BF-2A sub-menu.

5 Edit the breakpoint automation for the BF-2A side-chain filter. Control range is from 0 (the default setting where no filtering is applied to the side-chain) to 100% (maximum side-chain filtering).

To access the side-chain filter from a control surface:

1 Focus the BF-2A plug-in on your control surface.

2 Adjust the encoder or fader current targeting the Side-Chain Filter parameter.

To automate your adjustments, be sure to enable automation for that parameter as described above. See the Pro Tools Reference Guide for complete track automation instructions.