The Klark Teknik ON 504 Quad Compressor/Limiter has been designed to give the studio or PA engineer comprehensive and convenient automatic control over gain and level. Four channels of compression are available in one unit of nineteen inch rack space. Even at this high packing density, the degree of control over each channel of audio is greater than that found on many conventional two channel compressor/limiters. As a Compressor, the DN504 can achieve almost undetectable dynamic range reduction by the use of sophisticated automatic attack and release circuitry. Or compression can be used as an effect in its own right with full manual control over Threshold, Ratio, Attack, Release and Gain. There is also a switchable ‘Knee’ control which provides the option of Hard or Soft compression styles.