The A-121s is a dual Multimode filter suitable for filtering in stereo patches, but also dual mono and serial interconnection. The filter consists of two separate but similar filter cores that share cutoff and resonance as common controls. Since the A-121s is a true state-variable filter, each channel can be continuously varied in characteristic from Lowpass through notch and highpass to bandpass. In link mode, the characteristic of filter 2 (type 2) corresponds to the setting of the first filter. CV inputs with and without (bipolar) attenuators offer maximum flexibility regarding the modulation possibilities of individual and common parameters. The QM/TM 1/2 inputs can be assigned to the Type or Resonance parameters per filter on the rear panel via jumper. The audio inputs and some of the control voltage inputs are normalized, so depending on patch one modulation source is sufficient to control two equal parameters. Due to the slope of 12dB the dual filter shines with a soft, round sound whose resonance does not color too much.
