Description – Altec Lansing 1715C User Manual
Page 4
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1781A/1781AT
The
Altec Lansing 1781A/1781AT Programmable
Input modules accepts either mic or line level
signals through a wide variety of connector inter
faces. Standard features include an electronically
balanced input stage with adjustable gain, continu
ously variable high and low pass filters, RFI protec
tion, 48 volt phaptom powering two levels of
muting, and remote volume control capability.
Programming with plug-in jumpers which may
select phantom power (on or off), mute priority or
slave, or remote volume control. The
1781AT
module also comes equipped with a
1785A Input
Isolation Transformer which provides an additional
10 dB of gain for improved sensitivity.
Description
Block Diagram of the 1781A/1781AT Input Module
1781A/1781AT Specifications
Gain:
Total Harmonic
1781A:
0 dB - 50 dB,
continuously Vciriable
Distortion (THD):
(Ref. 1 kHz, 100 mVrms
output, minimum gain, 10 kfi
1781 AT:
10 dB - 60 dB,
load, 30 kHz low p>etss filter)
continuously varicible
20 Hz - 20 kHz:
<0.03%
Input Sensitivity:
(Ref. 1 kHz, 10 kfi load)
Equivalent Input Noise:
(Ref. 0 dBr = 100 mVrms
1781 A:
-68 dBu to -18 dBu
(0.3 mVrms - 100 mVrms)
output, 10 kfi load, 200 fi
input termination meiximum
1781 AT:
-78 dBu to -28 dBu
(0.1 mVrms - 30 mVrms)
getin, A-weighted)
<-120 dBr
Input Impedance:
(Ref. 1 kHz)
High Pass Fiiter (Low Cut):
(Ref. 100 mVrms output,
Electronically beilanced:
>8 kfi
minimum geiin, 10 kfi load)
Transformer balanced:
With 1793 Dual Phono
200 fl - 600 fi
Comer Frequency:
320 Hz
(>10dBat 100 Hz)
Connector Installed:
>39 kfi
Slope:
6 dB/oct (20 dB/dec)
Frequency Response:
(Ref. 1 kHz, 100 mVrms
output, 10 kfi load)
Low Pass Filter (High Cut):
(Ref. 100 mVrms output,
minimum gciin, 10 kfi load)
1781A:
Comer Frequency:
5 kHz
±1 dB (minimum gaiin):
20 Hz - 20 kHz
(>6 dB at 10 kHz)
± 1 dB (maximum gain):
1781AT:
50 Hz - 20 kHz
Slope:
6 dB/oct (20 dB/dec)
±1 dB (minimum g
2
un):
20 Hz - 20 kHz
Attenuation:
(Ref. 100 mVrms output.
±1 dB (meiximum gedn):
50 Hz - 15 kHz
Mute:
minimum gain, 10 kfi load)
>60 dB
(10 kfi remote)