Altec 1750a manual

Page 1

ALTEC

1 750A
28 Band

KEY SPECIFICATIONS

Type:

Frequency Response:
(reference 1 kHz)

THE:
(0 dBrn output, unity gain)

IMD (SMPTE):
(0 dBm output, unity gain)

Noise:
(unity gain, unweighted)

Dynamic Range:
load Impedance:
Operating Gain:

Available Gain:

Active filter set with 28
constant-Q minimum
phase shift band-
rejection filters at ISO
preferred 1/3 octave
center frequencies.

20 Hzto 20 kHz, + OH dB.

<0.03%.

<0.03%.

>~82 dBm.

>110 dB.

600 ohms orhigher.
MB.

20 dB

(to restore equalization losses).

DESCRIPTION

In the tradition of striving for the highest quality and reliability,
Altec Lansing introduces the 1750A Equalizer backed by a vast
knowledge of equalization technology. The 1750A is designed to
provide cost-effective accurate control for the custom tailoring of
frequency response in any professional or industrial application.

The 1750A features 28 constant-Q active band-rejection
filters at the ISO preferred 1/3 octave center frequencies from
31.5 Hz to 16 kHz. Each filter section provides up to 15 dB of
attenuation at its center frequency and is designed to skirt with
adjacent filters for minimum ripple and optimum combining
characteristics over a wide range of control settings. A 20 dB gain
control is provided to restore equalization losses.

The variable high-pass filter, with a slope of 18 dB per octave,
allows adjustment of the systems lower cutoff frequency from below
20 Hz to 160 Hz. The variable low-pass filter also has a slope of
18 dB per octave and can operate from 5 kHz to above 20 kHz,
providing a smooth high-end roll off. Other features include an
automatic AC dropout bypass, output muting that suppresses turn
on/off transients, XLR and barrier strip input and output con-
nectors, and electronically balanced input and output circuitry. The
universal power transformer permits 100, 120, 200, 220, 240
Vac, 50/60 Hz operation. In case of AC power loss, the capability
of silently switching to DC battery power is provided by a barrier
strip connector on the rear of the chassis. There are two optional
plug»in isolation transformers available: the 15550A input trans-
former and the 15560A output transformer

The Altec Lansing Model 1750A Equalizer is the choice among
professionals where precision room equalization is required.

Page 2

Input:

SPECIFICATIONS (continued)

(reference 0 dBv = 0.775 Vrms)

Type:
Impedance:

Nominal level:

Maximum Level:

Electronically balanced.
30 kohms balanced.

15 kohms unbalanced.
0 dBv (0.775 Vrms).
+24 dBv (12.3 Vrms)

Power requirements:
AC:

DC:

Operating Temperature

100, 120, 200, 220, 240 Vac, 50/60 Hz,
10 Watts.

Bipolar 24/28 Vdc at 200 mA (auto-
matic transfer to DC mode if AC power
fails)

Output: Range: Up to 60°C (140°F).
(reference 0 dBm = 0.775 Vrms across 600 ohms)
Type: Electronically balanced. Dimensions:
Impedance: 44 ohms balanced. Height: 3.5 inches (8.9 cm).
22 ohms unbalanced. Width: 19.0 inches (48.3 cm).
Maximum level: +24 dBm. Depth: 9.75 inches (24.8 cm).
High-Pass Filter: Variable low frequency cutoff from Weight:
below 20 Hz to 160 Hz with slope of Net: 10.7 lbs (4.9 kgs).
18 dB per octave. Shipping: 13.2 lbs (6.0 kgs).
Low-Pass Filter: Variable high frequency cutoff from 5 Enclosure: Rack-mount chassis.
kHz to above 20 kHz with slope of 18 18 GA steel main chassis.
dB per octave. 18 GA steel top, sides, rear cover.
3/16 inch (0.5 cm) aluminum front
Controls: 28 slide controls at 1/3 octave ISO panel
center frequencies from 31.5 Hz to
16 kHz, -15 dB cut. Color: Black.
, Gain, High-pass filter and Low-pass
filter controls. Accessories: "1402 Perforated Security Cover.
AC power switch (bypasses 1750A 1555M input isolation Transformer.
when shut off). 1556M Output Isolation Transformer.
conne°tinns= Altec Lansing continually strives to improve its
will: Fem! -3- products and their performance. Therefore, specifica-
Bamer Strip. tions are subject to change without any advance notice.
Output: Male XLR.
Barrier strip.
AC power: lEC power cord receptacle.
DC power: Barrier strip.
Block Diagram of 1750A
INPUT JUMPER W

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