Orban 621B Equalizer
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The Orban/Parasound 621 Parametric Equalizer
significant price/performance breakthrough in the
professional audio Equalizer
field. The 621 uses a
proprietary Orban/Parasound circuit to provide the user with
continuously variable control of the three parameters of
equalization: frequency of maximum equalization, bandwidth,
and amount of peaking or dipping. Each channel of the 621
provides four such equalization sections connected in
series, so that the total equalA sophisticated
"peak-stretching" overload indicator circuit continuously
monitors the output of each section, and flashes a
front-panel LED overload indicator for 1/2 second if peak
clipping occurs at the output of any section.
Approximately 12 dB of gain is available, as well as an
input level control. Thus the 621 can be used to make up
gain, or to interface medium-level circuits with line-level
circuits. The input level control also permits instant and
straightforward correction of overloads.
Each section of the 621 tunes over a 20:1 (4.3 octave)
For versatility, the frequency coverages of the various
sections overlap widely.
The equalization control permits a maximum boost of 16 dB,
and a maximum dip of minus infinity. This notching provision
permits the 621 to be used to remove hum or other
fixed-pitch interference with negligible effect on the sound
quality. In sound-reinforcement applications, it permits
extremely easy removal of major ring modes.
The use of "active R-C" circuitry means that the 621 is
resistant to magnetically induced hum. Overload-to-noise
ratio is typically 106 dB, and harmonic distortion at most
frequencies and output levels is less than 0.03%.
The 621 is an ideal replacement for any kind of Equalizer
currently used in professional sound, with the exception of
l/3-octave types used for "room tuning". The 621 can even do
a surprisingly effective job in that application,
partcularly if a dual-channel 62IB is used, with one channel
notching the four major ring modes and the other channel
providing broadband equalization.
Service and User Manual
1.41 Mbytes (1478195 Bytes)
01 January 1979
Scanned document, reading partly badly, partly not readable.
25 October 2017