Altec 1712a manual

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Page 1

ALTEC

LANSINGE

a MARK I V company

1 71 2A
Compressor/Limiter

wk Minimizes Coloration and Audible Side Effects ﬁr Automatic AC :DropoutBypass

* RMS-Calibrated Linear Integration Detector

KEY SPECIFICATIONS

Frequency Response:
(reference 1 kHz)

Threshold Range:

Compression Ratio:

Maximum Compression:

Attack Time:

Release Time:

output Gain:

THU:
(0 dBv input, unity gain,

20 Hz to 20 kHz, +0/-1 dB.

Continuously variable
from -45 to +20 dB.

Continuously variable
from 1:1 to oo:l.

60 dB.

Program dependent; 12 ms
for 10 dB input level above
threshold, 8 ms for 20 dB,
4 ms for 30 dB.

Program dependent; auto-
matically variable from

0 to 750 ms; affected by
front panel control settings.

Continuously variable
from -20 to +20dB.

<0.03%.

no compression, 30 kHz low pass filter)

(0 dBv input, unity gain,

<0.05% .

reference 1 kHz, up to 20 dB compression)

IMD (SMP'IE):

(0 dBv input, unity gain, <0.03%.

no compression)

(below maximum output,

output gain control at

<-86 dB.

+20 dB, 30 kHz low pass filter)

* Hard-Wired Bypass Switch

DESCRIPTION

The 1712A Compressor/Limiter addresses the
minimization of level differences between paging system
announcers and transient protection for loudspeaker systems.
Its feed-forward design permits compression ratios up to oo:1
with complete stability to automatically restrict the system
output to a predetermined level. Special compensation cir-
cuitry minimizes coloration and audible side-effects for virtu-
ally unmatched sonic qualities.

The single channel unit features an ans-calibrated lin-
ear integration detector. Its logarithmic output (linear in
decibels) closely matches the characteristics of the human
ear for a more natural sounding response when undergoing
gain changes. The detector is also compensated to prevent
peak reversion - a condition that occurs when low fre-
quency signals are below the period chosen for the integra-
tion time. Without correction, an rms or averaging detec-
tor would revert to peak detection resulting in an
overmeasurement of the low frequency energy. This causes
over-compression, increased distortion, and audible pump-
ing. The 1712A is free from these side effects.

The input level for a 0 dB reference is determined by
an internal jumper which may select -10, 0, +4, or +8 dBv.
This permits interfacing with virtually any industry standard
line level. Two LED arrays simultaneously display gain re-
duction and output level for effective monitoring of system
operation. The continuously variable Threshold, Compres-
sion Ratio, and Output Gain controls are recessed in screw-
driver slotted adjustments to minimize inadvertent changes
to the control settings. Program-dependent attack and re-
lease times assure natural sounding compression without the
need for continuous manual adjustment. The Altec Lansing
model 1712A compressor/limiter is the choice among
professionals where serious level control and transient pro-
tection is demanded.

Page 2

SPECIFICATIONS (continued)

Input:
(reference 0 dBv = 0.775 V rms)
Impedance: 20K ohms balanced.
10K ohms unbalanced.
Nominal Level: Selectable by internal jumper for
-10, 0, +4, +8 dBv.
Maximum Level: +20 dBv (7.75 V rms).
Output:
(reference 0 dBm = 0.755 V rms across 6000th)
Impedance: 44 ohms balanced.
22 ohms unbalanced.
Maximum Level: +20 dBm (7.75 V rms).
Controls and Switches: Threshold control,
Compression ratio control.
Output gain control,
Bypass switch,
Power switch.
Front Panel Indicators: Power LED,
Bypass LED,
Output level display indicating -
18 to + 14 dB,
Gain reduction display indicating -
I to -30 dB.
Connections:
Input: Female XLR.
3 terminal barrier strip.
Output: 3 terminal barrier strip.

AC: IEC power cord receptacle.

Power Requirements:
Operating Temperature
Range:
Dimensions:

Height:

Width:

Depth:
Weight:

Shipping:

Net:
Color:

Enclosure:

Accessories:

100, 120, 200, 220, 240 Vac, 50/
60 Hz, 12 Watts.

up to 60° C (140D F) ambient.

1.75 inches (4.45 cm).
19.0 inches (48.26 cm).
9.0 inches (22.86 cm).

10 lbs (4.55 kg).
6.3 |bs(2.85 kg).

Black.

Rack mount chassis,

18 GA steel main chassis,

18 GA steel top/rear cover,

1/16 inch thick black anodized alu-
minum alloyfront panel.

15560 600 ohm linetransformer.
I5550A15Kohm inputtransformer.

Design and Performance Approvals:

Meets the requirements of UL Stan-
dard 813.

Altec Lansing continually strives to improve products and perfor-
mance. Therefore, specifications are subject to change without

notice.