The Ashly XR-4001 Stereo 4-Way (Mono 7-way ) rackmount crossover is based upon a powerful state-variable filter circuit, which guarantees that two adjacent frequency band outputs always remain in phase. The XR-4001 Crossover offers a number of useful and unusual features, including continuous tuning, a response control, and a unique output stage which maintains low noise at any level setting. It also includes a 200:1 tuning range, output mute switch, and both TRS and XLR connectors. It features low noise and distortion, active balanced inputs, a peak level indicator, a precision regulated power supply, protection against abnormal input or output conditions, and rugged mechanical construction. The XR-4001 Crossover has a conservative design and an unusually thorough procedure for quality control have earned Ashly a reputation for dependability in the recording, sound reinforcement, and broadcast fields.Response Control; an Ashly Exclusive...This control, found adjacent to the crossover frequency control, adjusts the damping of the filter affecting the response shape of the filters at the crossover point. The dial calibrations refer to the amount of attenuation effected by the filter at the crossover frequency, i.e., a setting of 3dB means that the filter's high-pass and low-pass outputs are each "rolled off 3dB at the crossover point". This describes Butterworth filter response, or a gentle 3dB peak at the crossover point when the two filter output signals overlap. To obtain a flat signal, or "Linkwitz-Riley" response through the crossover region, set the Response control to "6". This attenuates each output of the filter by 6dB at the crossover point (two identical signals added together yield a +6dB increase). To obtain a notch at the crossover point, turn down the response control past "6" to best suit your needs.The purpose of this control is to help offset the inaccuracies inherent in typical loudspeakers, thereby helping you to achieve a flat system response. NOTE: The Response control is not a "slope" control. A 24dB/octave crossover will always have a slope of 24dB/octave. The Response control only affects filter response shape in the immediate vicinity of the crossover frequency; the ultimate crossover slope is a fixed parameter.About AshlyAshly is a name that's well-known among top sound reinforcement professionals, however, for those who don't know, it's a company that began over 30 yeas ago as a group recording engineers, concert sound professionals, and electronics designers who built elaborate custom consoles with built-in electronic crossovers, compressor/limiters, and parametric equalizers. Today, Ashly Audio is recognized as a world leader in quality signal processing equipment and power amplification.Initially, Ashly's first customers were friends and associates, and naturally, as with any product designed and built by those who actually use the gear professionally, demand grew--particularly for the individual signal processing components utilized in the mixers. This prompted Ashly to focus primarily on building rack devices that could be used in a modular fashion. Ashly also introduced the first commercial power amplifiers using power MOS- FET technology, and were among the very first to be approved by Lucasfilms for the popular THX movie theater sound systems.To this day, Ashly actively maintains their 32-year-long mission; "to offer only the highest quality audio tools at an affordable cost to the professional user, with all products engineered for manufacturing and servicing simplicity--ensuring reliability and long life." More than just words, we know of Ashly gear bought in 1982 that is still in use today with no signs of wear in the pots.