SPL Passeq - Passive Mastering Equalizer

With 72 passive filters per channel (36 x Boost, 36 x Cut), the Passeq surpasses all previous designs of this type by a wide margin. Each channel is divided into three Cut and three Boost bands, each offering 12 switchable frequency ranges. The Cut and Boost ranges are not identical; crossovers are designed to work with like a precise mechanic cogwheel so as to allow the engineer access to the largest possible number of optimal, wide-band S-curves with variable slopes.

A further remarkable Passeq feature is its individual sonic adaptation of each inductive filter through separate coil/condenser/resistor combinations: In stark contrast to earlier filter design and construction, each Passeq filter is optimized for the frequency assigned.
To insure the best possible signal warmth, richness and musicality in processing, coils for critical voice frequencies are custom-made for the Passeq.
This achieves the widest possible range and tonally appealing sound color palette from any passive EQ.

• The most powerful passive EQ ever made—144 (!) passive filters (72 per channel) in one EQ.
• Individual coils per filter.
• Single core coils, which means that every one is wound individually on its own dedicated core. This excludes sonic degradation from mutual influences while at the same time improving THD values.
• 120V makeup amplifiers based upon SPL unique SUPRA-OPs with 150dB dynamic rage and 200 v/ms slew rate.
• Individual design and component specificity for each filter.
• Custom made coils for critical mid-frequency ranges.
• Boost and cut crossovers mesh perfectly so that with the high number of frequencies one can dependably command the most elaborate set of response curves that to date any passive EQ has offered.
• Transformers from Lundahl with perfectly matched sonic characteristics provide for balanced I/O stages.