TOA Electronics 1000 Series - Manual (Page 3)

General Description
The E-1231 is a single channel, 1/3 octave active graphic equalizer designed to
allow clean, accurate audio equalization for stage, studio, or commercial
applications.
The E-1231 provides 12dB of boost or cut at each of its 28 frequencies, which
are centered at ISO 1/3 octave increments from 31.5Hz to 16kHz.
The E-1231's active bandpass/bandreject filters are designed for minimum
phase shift, and feature smooth slide controls with center detents for easy and
accurate adjustment. (The filters are summed in parallel for reliability, so that
the failure of one filter does not interrupt operation of the others.)
In addition, continuously variable highpass filters are provided on the front
panel. The highpass filter has a slope of 12dB per octave and is variable from
15Hz to 300Hz, while the lowpass filter can set for either a 6dB per octave
slope or a 12dB per octave slope and is variable from 2.5kHz to 30kHz.
An input level control on the E-1231 gives ±12dB of adjustment to allow a wide
variety of input sources. A LED indicator illuminates when either the input or the
output comes within 3dB of clipping. In addition to the usual EQ in/out switch,
an automatic EQ bypass function provides complete equalization bypass in the
event of loss of AC power, and an output muting function suppresses turn-
on/turn-off transients.
A security cover is included with the E-1231 to guard against accidental
disturbance, or intentional tampering when used in fixed installations.
The E-1231 can be mounted in a standard 19" rack and occupies 3-1/2" of
vertical space.
Features
1. 28 filters on ISO 1/3 octave center fre-
quencies from 31.5Hz to 16kHz.
2. 12dB boost or cut at each center frequen-
cy, continuously variable.
3. High quality, low phase-shift active filters.
4. Precision calibrated, noiseless slide con-
trols with center detent.
5. Equalizer In/Out switch.
6. Continuously variable highpass and low-
pass filters.
7. LED peak indicator to detect clipping at
input or output levels.
8. Variable input level control to accept varie-
ty of input sources.
9. Automatic EQ bypass circuitry.
10. A security cover is included.
11. Filter In/Out switch
12. Lowpass filter can be set for either
6dB/oct or 12dB/oct.
13. Optional input/output transformers that
convert electronically balanced input/out-
put to transformer balanced input/output.
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