1780A AND 1780AT
MIC/LINE INPUT MODULE

DESCRIPTION

The ALTEC LANSING 1780A and 1780AT MicILine input modules combine basic microphone preamplification with true line level input capability. Each module has a built-in resistive pad to permit levels in excess of +10 dBm and their high input impedance easily allows sixteen modules to be driven from a single low impedance source. In addition, both modules have a 300 Hz high pass filter, phantom power capability, L + R stereo summing, and from 0 to 50 dB of continuously variable gain. They are 100% compatible with all 1700-series mainframes and accept any one of the 1790-series connectors. The AT-version includes a 10 kn input bridging transformer for those who prefer transformer isolation. Unlike the 1781A, neither has muting (priority or slave), remote volume control capability, or continuously-variable high and low cut filters.

SPECIFICATIONS

(Reference 0 dBu = 0.775 v rms)
Gain: 0 dB - 50 dB, continuously variable Input Sensitivity:
Without pad -58 dBu to -8 dBu
(1 mv rms to 312 mv rms) With pad -38 dBu to +12 dBu
(10 mv rms to 3.12 v rms)
Input Impedance:
1780A 10 k n
1780AT 10 ko With 1793
Dual Phono 40 kf1
Frequency
Response: 50 Hz - 20 kHz, ±1 dB
25 Hz - 40 kHz, ±3 dB
Total Harmonic
Distortion:
(Ref. minimum gain, 50 Hz - 20 kHz measurement
bandwidth, 30 kHz low pass filter) 1780A - 0.01%
1780AT - 0.025°I°
Equivalent Input
Noise: -120 dBr
(Ref. 0 dBr = 100 mv rms output, 10 kf2 load, 200
input termination, maximum gain, A-weighted)
High Pass Filter:
Corner frequency: 300 Hz Slope: 12 dB/octave
Controls: 1- Gain, continuously variable Weight (Net):
1780A 2.5 oz. (70 gr)
1780AT 3.0 oz. (85 gr) Power Supply
Requirements: ±18 VDC at 15 ma DC (Supplied by mainframe)
Included
Accessories: 1- 2-pin female jumper (for phantom power) 2 - mounting screws
(for potentiometer bracket) 1 - Operating Instructions