Rockford Fosgate OEQ-1, Owner'S Manual

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INTRO
OEQ-11
DUCTION
The Rockford Fosgate OEQ-1 is a quiet, flexible nine-band
equalizer designed to correct response errors in autosound
installations. As car stereo systems become more sophisti-
cated, the unpredictable colorations of typical speaker in-
stallations are becoming less acceptable. The OEQ-1 offers
a convenient method of solving response problems without
system re-designs.
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Nine-Band
High-Q
Filter System
(IS0 Center Frequencies)
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±9dB Control Range Each Frequency
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±1/2 Octave Frequency Control Each Frequency
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Over 90dB Signal-to-Noise Ratio (A-Weighted)
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Fully-Floating High-Voltage Power Supply
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Defeat Switch (Bypasses all circuitry)
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Jeweler’s Screwdriver Control Adjustments
DESIGN
NINE-BANDS: Eight Octave-wide bands and one two-Oc-
tave band of boost and cut are employed in the OEQ-1. One-
Octave bands are the minimum required for effective control
over the bass and midrange; the two-Octave-wide 12kHz
band controls the very high “tingle” region where tonal
perception is less critical.
HIGH-Q FILTERS: Filter “Q” or quality factor is a measure of
the “narrowness” of the filter response: a high-Q filter affects
a narrow band of frequencies and a low-Q filter affects a wide
band. Most octave equalizers use relatively low-Q filters in
order to avoid large response ripples when all controls are at
maximum or minimum. However, the wide band of low-Q
filters allows adjustments made on one control to strongly
affect the neighboring frequencies, especially at modest
boost or cut. In addition, relatively narrow response prob-
lems cannot be fully cancelled by a wide-band filter.
The rationale for reducing filter Q to avoid max-control ripple
is in error, since it is a situation which realistically never
should happen. By using relatively high Q (over 2.0), the
OEQ-1 avoids much of the adjacent-band overlap that is
time consuming to adjust out.