SPL PASSEQ Passive Mastering Equalizer for Pro Audio Applications (All Black) - Manual (Page 7)

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Introduction
King of the passive equalizers
The PASSEQ Mastering Equalizer is a dual-channel, passive equalizer.
The PASSEQ Mastering Equalizer – Model 1650/1654 is a new revised edition of the well-
known SPL Passeq – Model 2595.
Both units are based on our 120V Rail Technology. The new PASSEQ Mastering Equalizer
features the same high-quality characteristics as the previous model, though it was
revised and optimized to fulfill all requirements of a Mastering Equalizer.
The Passeq of the first generation was the first passive equalizer which provides three
separate frequency ranges for the boost and the cut stages. With 12 switchable frequen-
cies per band, totaling 36 boost and 36 cut frequencies, the Passeq was the most power-
ful passive EQ system ever made. The new PASSEQ Mastering Equalizer features the same
amount of cut and boost frequencies, though the choice of frequencies was changed and
the Q-factor was individually newly adjusted for every selectable frequency with an opti-
mal coil, condenser, resistor combination. Each boost and cut frequency now got an indi-
vidual optimized Q factor. Especially the mid bands are much more harmonious for work-
ing on program material than they were on the previous model. When we were fine-tun-
ing, through component selection, within countless listening sessions, the focus was on
receiving musically sounding curves, which are clearly on par with legendary devices like
the Pulteq EQ from the decades of the 1950’s and 60’s, but without all disadvantages
of a 60-year-old original, like a high noise level and most of all a very limited choice of
frequencies.
All passive filter components (variable resistor, capacitor and coil) deliver excellent sonic
characteristics. An important part of this process is played by coil and condenser loading
and saturation characteristics. The resulting inertia in contrast to the characteristically
extremely fast reaction of active filters is the reason for pleasant, beneficial sonic char-
acteristics. We tend to perceive these attributes in terms of an increased suppleness and
transparency, with perceptibly improved, silky highs and warm and punchy basses.
Another highlight of the new PASSEQ is the HF+ Band, which was expanded with the fre-
quencies 25kHz and 35kHz, sounding so incredibly good, that you don‘t want to turn it off
anymore.
Thanks to the big detented output control, you can increase or attenuate the output level
by 10dB, to reach following devices with the perfect desired level. This is important, espe-
cially when it comes to mastering. A fader ranging from 0dB to limitless, like the previous
model provided, would not be helpful in this case. With the PASSEQ you can also adjust
the parameters Gain, Q (HF +) and Output in 41 steps with the detented potentiometers.
All other parameters can be adjusted with 12-position switches. Thanks to these switches
and detented potentiometers, a precise recall is very easy to realize.
In addition to that, the handling of the PASSEQ Mastering Equalizer was improved through
small corrections of the positioning and naming of the control elements. Like all new
SPL Mastering devices, the new SPL PASSEQ provides an Auto Bypass. Of course each
of the two channels can also be manually activated or deactivated with the big illumi-
nated pushbuttons. Thanks to the Auto Bypass, this can also be realized automatically in
a freely selectable time frame.