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 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.

1781 A/1781 AT Specifications

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

Input Sensitivity: (Ref. I kHz, 10 ki2 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 kS2
Transformer balanced: 200 fl - 600 fl With 1793 Dual Phono
Connector Installed: >39 kil

Frequency Response: (Ref. I kHz, 100 mVrms
output, 10 kDW load)
1781A:
± 1 dB (minimum gain): 20 Hz - 20 kHz
±1 dB (maximum gain): 50 Hz - 20 kHz
1781 AT:
_* I 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 12 input termination maximum gain, A-weighted) <-120 dBr

High Pass Filter (Low Cut): (Ref. 100 mVrms output, minimum gain, 10 kSl 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 dBJoct (20 dB/dec)

Attenuation: (Ref. 100 mVrms output,
minimum gain, 10 kSl load)
Mute: >60 dB
(10 ki21 remote)