Buzz Audio REQ 2.2
The REQ is a combination of passive filter circuits and active amplifier stages. Parallel resonant chokes and capacitors form the frequency selective part of each band and these are coupled into the amplifier stage via the boost/cut control. The resulting equalisation is best described as "surreal" and it never sounds hard or harsh. The low frequencies remain tight and powerful with the high frequencies clear and well defined.
Many other equalizers using passive filters have limited centre frequency choices, but the REQ boasts 72 different frequencies split over four bands per channel. The high and low bands can be switched to bell or shelving mode and the two bell mid bands have two centre frequency ranges. Each band has a bandwidth (Q) control and if the high or low bands are switched shelf mode, this control reverts to a shelf "slope" control. In addition a passive high pass filter and a variable "saturation" module are provided. The saturation module converts the REQ into a more "vintage" sounding unit by adding harmonics to the signal via the use of a steel audio transformer driven by a "single ended" old style Class A amplifier (see distortion specs below). The low frequency response is also altered by the saturation control, depending on the position of this switch.