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 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.
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.