API 2500+ Stereo Bus CompressorThe API 2500+ Stereo Bus Compressor allows adjustment of sonic qualities to alter the punch and tone of the stereo mix. The 19 inch, rack mountable unit features a dual channel design that can be configured for stereo compression or for use as two separate units via a single compression setting. Features: API 2520 Op Amps Expanded variable threshold between 20dBu to +20dBu Selectable ratio, attack, and release times Patented THRUST filter with 3