Surround Compressor’s Link section provides the following parameters.
Link parameters
Circuit Type pop-up menu: Choose the type of circuit emulated by Surround Compressor. The choices are Platinum, Classic A_R, Classic A_U, VCA, FET, and Opto (optical).
Group pop-up menus: Set group membership for each channel—A, B, C, or no group (indicated by -). Moving the Threshold or Output Level slider for any grouped channel moves the sliders for all channels assigned to that group.
Tip: Press Command and Option while moving the Threshold or Output Level slider of a grouped channel to temporarily unlink the channel from the group. This lets you set independent threshold settings while maintaining the side-chain detection link necessary for a stable surround image.
Bypass buttons: Bypass the channel. If the channel belongs to a group, all grouped channels are bypassed.
Detection pop-up menu: Choose the signal type to exceed or fall below the threshold. Max uses the maximum level of each signal. Sum uses the summed level of all signals.
If Max is chosen and any of the surround channels exceeds or falls below the threshold, that channel (or group of channels) is compressed.
If Sum is chosen, the combined level of all channels must exceed the threshold before compression occurs.