Altec Lansing 1707C - Page 4

1781A/1781AT
Description
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 phantom 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.
+ IN
— IN
RIGHT CH
LEFT CH
GND
Block Diagram of the 1781A/1781AT Input Module
1781A/1781AT Specifications
Gain:
1781A: 0 dB - 50 dB,
continuously variable
1781AT: 10 dB - 60 dB,
continuously variable
Input Sensitivity: (Ref. I kHz, 10 kQ load)
1781A: -68 dBu to -18 dBu
(0.3 mVrms - 100 mVrms)
1781AT: -78 dBu to -28 dBu
(0.1 mVrms - 30 mVrms)
Input Impedance: (Ref. 1 kHz)
Electronically balanced: >8 k0
Transformer balanced: 200 Q - 600 Q
With 1793 Dual Phono
Connector Installed: >39 kN
(Ref. 1 kHz, 100 mVrms
output, 10 kf) load)
Frequency Response:
17814:
X] dB (minimum gain): 20 Hz - 20 kHz
+1 dB (maximum gain): 50 Hz - 20 kHz
1781AT:
+1 dB (minimum gain): 20 Hz - 20 kHz
+1 dB (maximum gain): 90 Hz - 15 kHz
Total Harmonic
Distortion (THD):
20 Hz - 20 kHz:
Equivalent Input Noise:
High Pass Filter (Low Cut):
Comer Frequency:
Slope:
Low Pass Filter (High Cut):
Comer Frequency:
Slope:
Attenuation:
Mute:
(Ref. 1 kHz, 100 mVrms
output, minimum gain, 10 kN
load, 30 kHz low pass filter)
<0.03%
(Ref. 0 dBr = 100 mVrms
output, 10 kM load, 200 Q
input termination maximum
gain, A-weighted)
<-120 dBr
(Ref. 100 mVrms output,
minimum gain, 10 kf) load)
320 Hz
(>10 dB at 100 Hz)
6 dB/oct (20 dB/dec)
(Ref. 100 mVrms output,
minimum gain, 10 kQ load)
5 kHz
(>6 dB at 10 kHz)
6 dB/oct (20 dB/dec)
(Ref. 100 mVrms output,
minimum gain, 10 kQ load)
>60 dB
(10 k(2 remote)