The A-121-3 Multimode VCF from Doepfer is a slim built Multimode Filter with four different characteristics. If you know Dark Energy III from the same company, you can directly assign the sound of this analog 12 dB filter With Lowpass, Bandpass, Highpass and Notch , the four most common filter characteristics are available. In addition to the two CV inputs for the cutoff controller, a CV input for resonance has also been implemented.