Altec Lansing 1715C User Manual
Page 3
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1780A/1780AT
Description
The
Altec Lansing 1780A/1780AT Mic/Line Input
modules combine basic microphone preamplifi
cation with tme line level input capability. The
module heis a built-in resistive pad to permit levels
in excess of 0 dBu and its high input impedance
easily 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
-I-
R stereo summing, and 0 to 50 dB
of continuously variable gain. Included in the
1780AT version is a 10 kii input bridging trans
former for those who prefer transformer isolation.
Block Diagram of the 1780A/1780AT Input Module
1780A/1780AT Specifications
Gain:
0-50 dB, continuously
High Pass Filter:
Vciriable
Comer Frequency:
300 Hz
Slojje:
12 dB/octave
Input Sensitivity:
Without Pad:
-68 dBu to -18 dBu
(.3 mVnns to 100 mVrms)
Controls:
1 - Gain, continuously
With Pad:
-48 dBu to -1-2 dBu
(3 mVrnis to 1 Vnns)
Weight (Net):
variable
Input Impedance:
1780A:
2.5 oz. (70 g)
1780A:
lOkil
1780AT:
3.0 oz. (85 g)
1780AT:
lOkil
With 1793 Dual Phono:
40 kn
Power Supply
Requirements:
±18VDCat 15maIX:
Frequency Response:
50 Hz - 20 kHz, ±1 dB
(supplied by meiinframe)
Total
Included Accessories:
1 - 2-pin female jumper
Harmonic Distortion:
(Ref. minimum gain,
(for phemtom jxiwer)
50 Hz - 20 kHz mecisurement
2 - mounting screws
bandwidth, 30 kHz low-pass
(for potentiometer bracket)
filter)
1 - Operating Instmctions
1780A:
<0.01%
1780AT:
<0.025%
Equivalent Input Noise:
<-120 dBr
(Ref. 0 dBr = 100 mVrms out
put, 10 kil load, 200
il
input
termination,
maximum
gain,
A-weighted)