TDR Ultrasonic is a specialized filter designed to manage the ultrasonic frequencies that accumulate in oversampled recording, processing, or playback chains. Its main function is to prevent ultrasonic content from entering nonlinear systems, which can introduce unwanted distortion. Nonlinear systems such as peak limiters, distortion devices, compressors, and various modulation effects are prone to generating additional distortion when exposed to ultrasonic signals. Even analog devices like tape recorders and disc cutting systems, as well as playback equipment, exhibit nonlinear behavior that can impact audio quality.

The distortion caused by nonlinear systems increases with the bandwidth of the incoming signal, affecting both audible and inaudible frequencies. While narrow-band sounds like guitars or vocals can tolerate significant distortion creatively, wideband mixes are vulnerable to audible degradation from even slight saturation. This happens because nonlinearities create not only harmonic distortion but also intermodulation distortion, which generates new frequency components at the sums and differences of the original frequencies. These new components can fall into the audible range, negatively impacting the clarity and fidelity of the audio.

TDR Ultrasonic offers precise control over these effects by reducing the intermodulation distortion that ultrasonic content might introduce when passing through nonlinear devices. Its linear-phase filter features a continuously variable slope, complemented by innovative tools like a Dynamic Ultrasonic Gate and infinite attenuation enforcement at the Nyquist frequency. The interface is fully resizable and hardware accelerated, providing users with detailed ultrasonic frequency analysis and easy access to all filter parameters. This design enables effective A/B testing of ultrasonic filtering on entire mixes, ensuring enhanced audio quality in complex production environments.