Altec Lansing 1707C - Page 3

1780A/1780AT
Description
The Altec Lansing 1780A/1780AT Mic/Line Input
modules combine basic microphone preamplifi-
cation with true line level input capabilitv. The
module has a built-in resistive pad to permit levels
in excess of 0 dBu and its high input impedance
easilv allows sixteen modules to be driven from a
single low impedance source. Also, the module
offers a 300 Hz high-pass filter, phantom power
capability, L + R stereo summing, and 0 to 50 dB
of continuously variable gain. Included in the
1780AT version is a 10 kQ input bridging trans-
former for those who prefer transformer isolation.
INPUT
1780A/1780AT Specifications
Gain: 0 - 50 dB, continuously
variable
Input Sensitivity:
Without Pad: -68 dBu to -18 dBu
(.3 mVrms to 100 mVrms)
-48 dBu to +2 dBu
(3 mVrms to 1 Vrms)
With Pad:
Input Impedance:
1780A: 10 kQ
1780AT: 10 kQ
With 1793 Dual Phono: 40 kif
Frequencv Response: 50 Hz - 20 kHz, +1 dB
Total
Harmonic Distortion: (Ref. minimum gain,
90 Hz - 20 kHz measurement
bandwidth, 30 kHz low-pass
filter)
1780A: <0.01%
1780AT: <0.025%
Equivalent Input Noise: <-120 dBr
(Ref. 0 dBr = 100 mVrms out-
put, 10 kQ load, 200 © input
termination, maximum gain,
A-weighted)
High Pass Filter:
Comer Frequency:
Slope:
Controls:
Weight (Net):
17804:
Power Supply
Requirements:
Included Accessories:
* FB1 4 FB2 IN
Block Diagram of the 1780A/1780AT Input Module
300 Hz
12 dB/octave
1 - Gain, continuously
variable
2.5 oz. (70 g)
3.0 oz. (85 g)
+18 VDC at 15 ma DC
(supplied bv mainframe)
1 - 2-pin female jumper
(for phantom power)
2 - mounting screws
(for potentiometer bracket)
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