Description
The Altec Lansing 1781A/1781AT Programmable Input modules accepts either mic or line level signals through a wide variety of connector interfaces. Standard features include an electronically balanced input stage with adjustable gain, continuously variable high and low pass filters, RFI protection, 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.

Gain:
1781A: 0 dB - 50 dB,
continuously variable 1781AT: 10 dB - 60 dB,
continuously variable

Input Sensitivity: (Ref. 1 kHz, 10 k12 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. I kHz)
Electronically balanced: >8 ki2
Transformer balanced: 200 fl - 600 fl
With 1793 Dual Phono
Connector Installed: >39 kfl

Frequency Response: (Ref. I kHz, 100 mVrms
output, 10 ki2 load)
1781A:
±1 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): 50 Hz - 15 kHz

Total Harmonic
Distortion (THD): (Ref. I kHz, 100 mVrms output, minimum gain, 10 kfl load, 30 kHz low pass filter)
20 Hz - 20 kHz: <0.03%

Equivalent Input Noise: (Ref. 0 dBr = 100 mVrms output, 10 kfl load, 200 fl input termination maximum gain, A-weighted) <-120 dBr

High Pass Filter (Low Cut): (Ref. 100 mVrms output,
minimum gain, 10 kSt load)
Comer Frequency: 320 Hz
(>10 dB at 100 Hz)
Slope: 6 dB/oct (20 dB/dec)

Low Pass Filter (High Cut): (Ref. 100 mVrms output, minimum gain, 10 kfl load)
Comer Frequency: 5 kHz
(>6 dB at 10 kHz)
Slope: 6 dB/oct (20 dB/dec)

Attenuation: (Ref. 100 mVrms output, minimum gain, 10 kS2l load)
Mute: >60 dB
(10 kSZ remote)