The PBC-6A differs from many other audio compressors in a couple of ways: -NO THRESHOLD: Theres no threshold in the PBC-6A. Unlike compressors with threshold controls, the signal passing through the PBC-6A is always being com- pressed rather than compressing only those parts of the signal that are above a set threshold. This makes the PBC-6A a non-linear, compression amplifier (CA) -LEVEL DEPENDENT RATIO: The PBC uses a feedback configuration to help achieve its function. Along with this, the PBCs detector allows higher output signals to compress more than lower-level ones. With the lack of thresholding, the change in ratio is smooth and gradual from low-level signals to higher-level. -KNEE CONTROL: This allows a transition from lower-to-higher ratios to occur over a smaller range than would naturally happen due to the PBCs feedback and detector configuration.