Passive Mastering Equalizer The new dual-channel PASSEQ (Model 1650/1654) is the resolute evolution of the highly acclaimed predecessor Model 2595. The new PASSEQ now features Air band, a stepped output control ranging from -10dB to +10dB and a mid cut band now starting at 200Hz. These features were on the wish list of many mastering engineers. Furthermore we have exchanged capacitor arrays in the filters by custom-made single capacitors and optimized the bandwidth per frequency range. This evolution is a sonic revolution.