SPL Passeq EQ


Passive Equalizer

Manufacturer Description:

The Passeq complements our parametric Equalizers Qure and PQ 2050 by a classic design with passive coil filters and perfectly fulfills the highest expectations in all areas of audio processing, from recording through mixing to mastering. The superior sound qualities and musical characteristics of passive filters ideally meet increasing demands in creating manifold sound colors full of character.

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 made144 (!) passive filters (72 per channel) in one EQ. 
  • Individual coils per filter. 
  • 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. 
  • XLR contacts from Switchcraft. Switches and potentiometers from Elma and ALPS (including ALPS "Big Blue" with 41 steps). 
  • Internal, linear power supply featuring a generously proportioned toroidal transformer and voltage selection (110-120V, 60Hz or 220-240V, 50Hz).

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