TDR Elliptical specializes in controlling the stereo width at low frequencies. Elliptical filters operate on the stereo difference channel. They have important applications in disk mastering, and whenever the amount of positional information in a mix asks for control.

Contrary to traditional elliptical filters, this filter offers a continuously variable slope, minimum and linear phase modes, and a dry mix control. Various compensation options ranging from Dynamic Bump over harmonic generators to "Haas delays", permit the operator to creatively counter-act subjective energy losses introduced by the filtering and/or stereo to mono summing.

TDR Elliptical comes with a freely resizable user interface, including a frequency analyzer that offers insight into the stereo difference at lowest registers, down to DC.

Notable Features

• Minimum phase and linear phase operation
• Continuously variable filter slope
• Various filter energy compensation options, incl. Harmonic generators
• Effective 'stereo to mono" loss compensation
• Freely resizable hardware accelerated user interface, full-screen capable

Note: Elliptical filters are not to be confused with Elliptic filter specification. The latter is also called a Causer or Zolotarev-filter, and describes a way to specify "Q" in higher order filters (much like Butterworth, Chebychev, Linkwitz-Riley or Bessel). Elliptic filters tolerate ripple both in the stopband and passband, making them largely inadequate in audio applications.