Altec Lansing 1707C MIXER AMPLIFIER User manual

LANSING:'
1707C/1715C
Six Channel Mainframe
Mixer/Power Amplifier
KEY FEATURES
* Six ports for inputs or outputs
* Offers systemwide remote muting
* Built-in compressor/limiter
KEY SYSTEM SPECIFICATIONS
(Ref. 1 kHz)
+1 dB, 20 Hz - 20 kHz
(1 watt output)
+1 dB, 20 Hz - 20 kHz
(0.775 Vrms output, 600 Q
load)
Frequency Response:
Direct Output:
Preamp Output:
Total Harmonic
Distortion (THD):
Direct Output:
(Ref 1 kHz)
<0.05%, 20 Hz - 20 kHz
(rated output power,
30 kHz low-pass filter)
<0.05%, 20 Hz - 20 kHz
(0.775 Vrms output, 600 Q
load, EQ flat, compressor/-
limiter off, 30 kHz low-pass
filter)
Preamp Output:
Signal-to-Noise Ratio:
Direct Output:
(master at maximum)
Preamp Output:
>80 dB below rated output
power, A-weighted
>75 dB below 0.775 Vrms
output, A-weighted, EQ off,
compressor/limiter off
DESCRIPTION
The Altec Lansing 1707C/1715C Mixer/Power
Amplifier is a six channel user-configurable main-
frame amplifier. By selecting from the large array of
system component options, the 1707C/1715C can
become a six-in/one-out microphone mixer/amp-
lifier or a one-in/six-out distribution preamplifier.
The basic mainframe combines a fully protect-
ed 75-watt (for the 1707C) or 150-watt (for the
1715C) power amplifier with six ports which can
be input or output. Multiple 1707C/1715C main-
frames can be linked together for situations where
more then six input/output ports are required.
Built-in features include a trap-door on the top
panel for easy access into the unit, compressor/-
limiter, low and high frequency shelving equalizers,
muting, remote volume control capability, and a
tone generator which produces four different
sounds.
Input Modules: The Altec Lansing 1780A/-
1780AT Input module and the 1781A/1781AT
Programmable Input module accept either mic or
line level signals through a wide variety of connec-
tor interfaces.
Output Modules: The Altec Lansing 1783 Line
Output module allows the user to interface with
other professional equipment.
The Altec Lansing model 1707C/1715C mix-
er/power amplifier systems respond to most design
tasks with the ease and versatility of systems
costing much more. Às a result, it is the choice for
use in professional installations requiring high
quality, flexibility in design, and low cost.

Continuous Average
Power:
1707C:
1715C:
Maximum Midband
Output Power:
1707C:
1715C:
Power Bandwidth:
Direct Output:
Intermodulatlon
Distortion:
Direct Output:
Damping Factor:
Direct Output:
Rated Output Level:
Direct Output:
1707C:
1715C:
Preamp Output:
Transformer Output:
1707C:
1715C:
Equalization:
Bass:
Treble:
Compressor/Limiter:
Threshold:
Compression Ratio:
Release Time:
Tone Generator:
Tones:
Control:
Level Adjustment:
Protection Svstem:
Amplifier:
Load:
Front Panel Controls:
input:
Compressor/Limiter:
1707C/1715C Specifications (cont'd)
75 watts
150 watts
(Ref. 1 kHz at 1% THD)
100 watts
175 watts
(Ref. 1 kHz at rated output)
>20 Hz - 20 kHz
(SMPTE 4:1)
<0.1% at rated power
>40, 20 Hz - 1 kHz
(Ref. 1 kHz)
(unbalanced)
24.5 Vrms/8 Q load
24.5 Vrms/4 Q load
(unbalanced)
0 dBm, 600 2 min. load
(balanced)
17.4 Vrms/4 Q load
25.0 Vrms/8 2 load
70.7 Vrms/66.6 Q load
25.0 Vrms/4.2 Q load
34.6 Vrms/8 2 load
70.7 Vrms/33.3 Q load
(Shelving type)
+12 dB at 100 Hz
+12 dB at 10 kHz
Feedforward Topology
-20 dB to +20 dB
Continuously variable
(Ref. 100 mVrms on Link input)
1:1 to 0:1
Continuously variable
50 msec to 5 sec.
Continuously variable
Electronically produced
Buzzer, siren, single-tone chime,
and repeating tone chime
All tones are initiated by
external switch closures
Rear panel
e Short circuit current limiting
e Over voltage limiting
e Thermal sensing
e Spurious oscillatory protection
e Low AC line sensing
e Output DC detection
e Subsonic detection
e Tum-or/off transients (=3 secs)
6 - Input Level adjust
I - Release Time adjust
1 - Threshold adjust
1 - Compression Ratio adjust
EQ Controls:
Output:
Miscellaneous:
Rear Panel Controls:
Tone Generator:
Front Panel Indicators:
Connectors:
Amplifier Input:
Link Input:
Battery:
Amplifier Output:
Preamp Output:
Link Output:
Mute and Tone Generator:
Power Requirements:
AC Mains:
Battery:
1707C:
1715C:
Power Consumptlon
and Heat Produced:
1707C:
75 watts output:
25 watts output:
1715C:
150 watts output:
50 watts output:
Operating
Temperature Range:
Dimensions:
Width:
Height:
Depth:
Net Weight:
1707C:
1715C:
Finish Color:
Accessories Included
with Malnframe:
1 - On/Off switch
I - Bass adjust
1 - Treble adjust
I - EQ In/Defeat switch
I - Master Level adjust
l - AC Power switch
] - Output Level adjust
6 - Green LED's (Nominal Input)
6 - Red LED's (Peak Input)
I - Red LED (Main Output clip)
I - AC Power ON
I - RCA phono receptacle
I - RCA phono receptacle
I - 3-terminal barrier strip
I - 7-terminal barrier strip
1 - RCA phono receptacle
I - RCA phono receptacle
7 - Screw terminals
(Ref. 1 kHz, rated output
with no modules installed)
100/120/200/220/240 VAC,
50/60 Hz.
+48 VDC bipolar
1.5 amps maximum
3.0 amps maximum
165 w consumed, 306 BTU/hour
130 w consumed, 357 BTU/hour
320 w consumed, 578 BTU/hour
230 w consumed, 612 BTU/hour
Up to 50°C (122°F)
19 inches (48.3 cm)
5% inches (13.3 cm)
13 inches (33.0 cm)
25 lbs. (11.4 kg)
32 lbs. (14.5 kg)
Black
1 - Operating/Service Instructions for Mainframe,
1780A/AT, 1781A/AT and 1783
l - Preamp Out to Amp In “U” Shorting Bar
l - Direct Output to OT in Shorting Bar
] - System Configuration Label
1 - International 220/240 VAC voltage decal
l - International Fuse decal and fuse
1 - Rack mount hardware kit
Altec Lansing continually strives to improve their products and
performance. Therefore, specifications are subject to change
without notice.

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)
| - Operating Instructions

1781A/1781AT
Description
The Altec Lansing 1781A/1781AT Programmable
Input modules accepts either mic or line level
signals through a wide variety of connector inter-
faces. Standard features include an electronically
balanced input stage with adjustable gain, continu-
ously variable high and low pass filters, RFI protec-
tion, 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.
+ IN
— IN
RIGHT CH
LEFT CH
GND
Block Diagram of the 1781A/1781AT Input Module
1781A/1781AT Specifications
Gain:
1781A: 0 dB - 50 dB,
continuously variable
1781AT: 10 dB - 60 dB,
continuously variable
Input Sensitivity: (Ref. I kHz, 10 kQ 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. 1 kHz)
Electronically balanced: >8 k0
Transformer balanced: 200 Q - 600 Q
With 1793 Dual Phono
Connector Installed: >39 kN
(Ref. 1 kHz, 100 mVrms
output, 10 kf) load)
Frequency Response:
17814:
X] 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): 90 Hz - 15 kHz
Total Harmonic
Distortion (THD):
20 Hz - 20 kHz:
Equivalent Input Noise:
High Pass Filter (Low Cut):
Comer Frequency:
Slope:
Low Pass Filter (High Cut):
Comer Frequency:
Slope:
Attenuation:
Mute:
(Ref. 1 kHz, 100 mVrms
output, minimum gain, 10 kN
load, 30 kHz low pass filter)
<0.03%
(Ref. 0 dBr = 100 mVrms
output, 10 kM load, 200 Q
input termination maximum
gain, A-weighted)
<-120 dBr
(Ref. 100 mVrms output,
minimum gain, 10 kf) load)
320 Hz
(>10 dB at 100 Hz)
6 dB/oct (20 dB/dec)
(Ref. 100 mVrms output,
minimum gain, 10 kQ load)
5 kHz
(>6 dB at 10 kHz)
6 dB/oct (20 dB/dec)
(Ref. 100 mVrms output,
minimum gain, 10 kQ load)
>60 dB
(10 k(2 remote)

1783
Description
The Altec Lansing 1783 Line Output modules pro-
vides the drive capability necessary to interface
with other professional equipment. The electroni-
cally balanced output stage provides a low source
impedance to drive subsequent stages. If trans-
former isolation is necessary,the module's circuit
board accomodates the optional PC-mount 1786
Output Isolation Transformer. The continuously
variable output level control is local to the module
permitting independent adjustment of each line
output.
1783 Specifications
Output Source
Impedance: «50 Q
Nominal Output Level
[Load Impedance: +8 dBm
(Ref. 1 kHz, 0 dBm = 0.775
Vrms with 600 (2 load, output
level control at maximum, 100
mVrms input)
Maximum Output
Level: +24 dBm
Frequency Response: (Ref. 1 kHz, +8 dBm output)
+1 dB: 20 Hz- 25 kHz
Total Harmonic
Distortion (THD): (Ref. 1 kHz, +8 dBm output,
output level control at maxi-
mum, 30 kHz low pass filter)
20 Hz - 20 kHz: <0.05%
Signal to Noise Ratio: >88 dBm
(Below +8 dBm output, out-
put level control at maximum,
A-weighted)
Power Requirements: +18 VDC at 20 mA
(supplied by mainframe)
1786 Output Isolation Transformer
Impedance Ratio:
1:1 (600 0:600 N)
Frequency Response: (Ref 1 kHz, +18 dBm output)
+] dB: 20 Hz - 20 kHz
Total Harmonic
Distortion (THD): Ref 1 kHz, +18 dBm output)
20 Hz - 20 kHz: «0.596
50 Hz - 20 kHz: «0.196
Special Ordering Instructions
NOTE: The modules listed below are required
for use with the 1707C/1715C and must be
ordered separate from the mainframe.
Plug-in Input Modules:
1780A Mic/Line Input module
1780AT Mic/Line Input module with 10 kQ
bridging transformer installed
1781A Programmable Input module
1781AT Programmable Input module with
model 1785A 600 22 to 10 kQ
isolation transformer installed
1785A 600 Q to 10 kQ Input Isolation
Transformer for installation on
existing model 1781A
Plug-in Output Module:
1783 Line Output module
1786 Output Isolation Transformer
Plug-in EQ Module:
8751A Programmable 14-Band EQ module
NOTE: Each module selected requires one of
the following connectors also be ordered:
1791 1792
Female XLR Male XLR
1798 1794
Dual RCA Phono r
5-Lug Terminal

CONFIGURING THE MAINFRAME
The Mainframe's Inner Workings
MODULE OUT "NOMINAL yoyo ‘PEAK’
100mV RM
ZIN-
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IN
Tr
1
INPUT OUTPUT MIX OUT
INPUT
with mainframe LEVEL SUM
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BUZZER P
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li
DIN
SHELVING
EQUALIZER
BASS TREBLE
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THRESHOLD COMP REL ,
RATIO TIME |
100mY RMS
Z IN - 10K
LEVEL
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LINK OUT
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0.775V AMS
AMPIN
AUX DUT MASTER
POWER
AMPLIFIER
BARRIER
TRANSFORMER STRIP
POWER ON E A
ue a VOLTAGE
POWER SAC UNE SELECTOR |
SWITCH FUSE
100/120/200/220/
240VAC 50/60HZ
JK USER INSTALLED STRAPS
+V VOLTAGE
POWER du RAILS
SUPPLY
ó 6 à i
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*48V OC INPUT
1707C/1715C System Block Diagram
ARCHITECT'S and ENGINEER'S SPECIFICATION
The mixer/power amplifier shall have six configurable
ports and be capable of operating from 100, 120, 200,
220, or 240 Vac, 50/60 Hz line, or from +48 VDC.
Each port shall be usable with a microphone or other
high level device. The mixer/power amplifier main-
frame shall include a compressor/limiter, low and
high frequency shelving equalizers, and a tone
generator capable of producing general purpose and
emergency warning signals.
The power amplifier shall meet the following perfor-
mance criteria: Power Output: 75 watts (1707C) at
less than 0.05% THD from 20 Hz to 20 kHz (8 Q direct
output), or 150 watts (1715C) at less than 0.0596 THD
from 20 Hz to 20 kHz (4 2 direct output). Frequency
Response: 20 Hz to 20 kHz, +1 dB (direct output).
Source Impedance: 150 Q to 250 Q nominal with a
microphone preamplifier, 600 Q with a bridging
transformer, 150 (2 to 600 Q with a line matching
transformer, and greater than 30 kQ with a tape
preamplifier. Equivalent Input Noise: «-120 dBr with
a low impedance microphone preamplifier. Output
Noise: «-85 dBm (with all controls off).
The mixer/power amplifier shall be rack mountable
and finished in black. The amplifier's dimensions
shall be 514" (H) x 19" (W) x 12%" (D) and its net
weight shall be 24.2 lbs. (1707C), or 30.8 lbs.
(1715C).
The plug-in accessory modules shall be the 1780A/AT
and the 1781A/AT Input modules and the 1783 Line
Output module. The accessory transformers usable
with the modules shall be the 1785A Input Isolation
transformer and the 1786 Output Isolation transform-
er. The connector subassemblies shall be the 1791
female XLR, 1792 male XLR, 1793 dual phono, and
the 1794 5-lug screw terminal connector.
The mixer/power amplifier shall be the Altec Lansing
Model 1707C/1715C.
ALTEC
LANSING
a MARK IV company
P.O. BOX 26105 e OKLAHOMA CITY, OK 73126-0105 e U.S.A. e 405/324-5311 or FAX: [phone]
© 1992 ALTEC LANSING CORPORATION
PRINTED IN U.S.A. 7/92
Revision 1
42-07-029244

ALTEC
the sound of experience
1707C & 1715C
Mixer/Power Amplifiers
Operating and Service Instructions
ALTEC LANSING CORPORATION
MA
a RK IV companv
P.O. Box 26105 e OKLAHOMA CITY, OK e 73126—0105 e 405—324—5311 or FAX 405—324—8981

Table of Contents
Section
SPECIFICATIONS
ELECTRICAL CONNECTIONS FOR THE 1707C/1715C
MIXER/POWER AMPLIFIERS
Power Connections (120 Volt, 50/60 Hz)
Power Connections (100, 200, 220, or 240 Volt; 50/60 Hz)
INSTALLING MODULES IN THE MAINFRAME
SHELF OR RACK MOUNTING THE 1707C/1715C
MIXER/POWER AMPLIFIERS
Ventilation
CONFIGURING THE MAINFRAME
The Mainframe's Inner Workings
Output Connection
Output Fuse
Mute/Tone Generator Connections
The Rear-Panel Output-Level Control
Resistance Effects of Long-Cable Runs on Mute —
and Tone-Generator Circuits
LINK IN/LINK OUT Connections
PREAMP OUT/AMP IN Connections
AUX OUT Connections
Battery Input Connections
FRONT/REAR-PANEL CONTROLS, SWITCHES, INDICATORS,
AND CONNECTORS
INITIAL SETUP AND OPERATION OF MAINFRAME WITH
MODULES INSTALLED
Initial Setup of an Input Module
Initial Setup of an Output Module
Initial Setup of the Mainframe
Operating the 1707C/1715C Mixer/Power Amplifiers
SERVICE INSTRUCTIONS
SERVICE INFORMATION
Power Amplifier Bias Adjustment
Power Amplifier DC Offset Adjustment
Parts Ordering
Factory Service
Technical Assistance
Pants List |
List of Tables and Figures
Table I. AC Line Voltage Selection and Strapping Chart
Table Il. AC Fuse Selection Chart
Table lil. Maximum Allowable Cable Resistances
Figure 1. Top-Cover Removal
Figure 2. Location of Voltage Selection Terminal Block
Figure 3. Application of International Stickers
Figure 4. Module Installation
Figure 5. Removal of Blank Cover Panel
Figure 6. System Configuation Label
Figure 7. Block Diagram of 1707C/1715C Mixer/Power Amplifiers
Figure 8. Direct Output Connections
Figure 9. Transformer Output Connections
Figure 10. Mute/Tone Generator Switch Connections
Figure 11. Typical Linking Connections
Figure 12. Patching an External Equalizer or Other Signal Processing
Devices
Figure 13. Battery Input Connections
Figure 14. Front-Panel Controls, Switches, and Indicators for the
1707C/1715C
Figure 15. Rear-Panel Control and Connectors for the 1707C/1715C
Figure 16. Schematic of the 1707C/1715C Mainframe
Page
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Description
The 1707C and 1715C Mixer/Power Amplifiers offer a
highly flexible integration of a user configurable six input
mixer with a fully protected power amplifier in one con-
venient cost effective package.
The six input ports accept any of the several input
modules or output module. The programmable input
modules may have their muting circuitry configured in
either "priority", "slave" mode, or may be set to ignore
muting commands. When a module configured in the
"Priority" mode is activated, modules in the "slave" mode
will be muted.
Circuitry is also provided to allow remote volume
control of individual inputs.
Multiple mainframes may be dynamically linked
together. Separate preamp-out and amplifier-in jacks allow
the insertion of equalizers or other signal processing
between the mixer and the power amplifier.
A multi-tone generator and a compressor/limiter are
also provided.
Continuous
Average Power:
1707C:
1715C:
Maximum Midband
Output Power:
1707C:
1715C:
Power Bandwidth:
Direct Output:
Transformer Output:
Frequency Response:
Direct Output:
Transformer Output:
Link Output:
Preamp Output:
Specifications
Input Sensitivity / Input Impedance:
75 watts
150 watts
(Reference 1 kHz at 196 THD)
100 watts
175 watts
(Ref. 1 kHz at rated output
power)
better than 20 Hz — 20 kHz
better than 50 Hz — 15 kHz
+1 dB, 20 Hz — 20 kHz
(Ref. 1 kHz, 1 watt output)
+1.5 dB, 50 Hz — 15 kHz
(Ref. 1 kHz, 1 watt output)
+1dB, 20 Hz — 20 kHz
(Ref. 1 kHz, 100 mVrms,
10 kQ load)
+1dB, 20 Hz — 20 kHz
(Ref. 1 kHz, 0 dBm output,
600 (2) load)
Total Harmonic Distortion (THD):
Direct Output:
Transformer Output:
Link Output:
Preamp Output:
Intermodulation Distortion:
Direct Output:
<0.05%, 20 Hz — 20 kHz
(Ref. 1 kHz, rated output
power, 30 kHz low-pass filter)
<1.0%, 50 — 100 Hz
<0.1%, 100 Hz — 20 kHz
(Ref. 1 kHz, rated output
power, 30 kHz low-pass filter)
<0.05%, 20 Hz — 20 kHz
(Ref. 1 kHz, 100 mVrms
output, 10 kQ load, 30 kHz
low-pass filter)
<0.05%, 20 Hz — 20 kHz
(Ref. 1 kHz, 0 dBm output,
600 © load, EQ flat,
compressor/limiter off,
30 kHz low-pass filter)
(SMPTE 4:1)
less than 0.1% at rated
power)
Input Sensitivity / Input Impedance:
(For rated output power, Ref. 1 kHz, 0 dBu = 0.775 Vrms)
Using 1780A/1780AT:
(balanced, no pad)
Using 1780A/1780AT:
(balanced, w/pad)
Using 1781A:
(balanced)
Using 1781AT:
(balanced)
Using 1781A+ 1785A:
(balanced)
0.3 to 100 mVrms / 10 KQO
(-68 dBu to -18 dBu)
3 mVrms to 1 Vrms / 10 kQ
(-48 dBu to +2 dBu)
0.3 to 100 mVrms / 10 KQO
(-68 dBu to -18 dBu)
0.1 to 30 mVrms / 600 2
(-78 dBu to -28 dBu)
0.1 to 30 mVrms / 6000
(-78 dBu to -28 dBu)
Link Input:
(unbalanced)
Amplifier Input:
(unbalanced)
Rated Output Level /
Minimum Load
Impedance:
Link Output (unbal):
Preamp Output (unbal):
Auxiliarv Output (unbal):
Direct Output:
1707C:
1715C:
Transformer Output:
1707C:
1715C:
Damping Factor:
Direct Output:
Signal-to-Noise Ratio:
Direct Output:
(master at minimum)
Direct Output:
(master at maximum)
Link Output:
Preamp Output:
Protection Systems:
Amplifter:
Load:
External DC Supply:
Mainframe:
Equalization:
Bass:
Treble:
100 mVrms / 10 kN
(-18 dBu)
0.775 Vrms / 10 kQ
(0 dBu)
(Reference 1 kHz)
100 mVrms (-18 dBu), 2 kQ
0 dBm, 600 (2 min. load
0 dBm, 600 (2 min. load
Unbalanced
24.5 Vrms / 8 () min. load
24.5 Vrms / 4 Q min. load
Balanced
17.4 Vrms / 4.0 Q min load
25.0 Vrms / 8.3 0 min load
70.7 Vrms / 66.62 min load
25.0 Vrms / 4.2 Q min load
34.6 Vrms / 8.0 Q min load
70.7 Vrms / 33.3() min load
>40, 20 Hz — I kHz
> 105 dB below rated
output power, À weighted.
>80 dB below rated output
power, Å weighted.
>75 dB below 100 mVrms
output, À weighted.
>75 dB below 0.775 Vrms
output, A weighted,
EQ defeated, compressor /
limiter off.
e Short circuit current
limiting.
€ Over voltage limiting.
€ Thermal Sensing.
e Spurious oscillatory
protection.
e Low AC line sensing.
e Output DC detection.
e Subsonic detection.
e Tum-on/tum-off
transients.
(approx 3 seconds)
e DC input fuses.
e AC line fuse.
Shelving Tvpe.
+12 dB at 100 Hz.
+12 dB at 10 kHz.
Note: 0 dBm into 600 (2 vields 0.775 Vrms.

Compressor / Limiter:
Threshold:
Compression Ratio:
Release Time:
Tone Generator:
Tones:
Control:
Level adjustment:
Connectors:
Inputs:
Amplifier Input:
Link input:
Batterv:
Outputs:
Amplifier Output:
Preamp Output:
Link Output:
Auxiliary Input:
Control:
Mute and
Tone Generator:
Controls:
Front Panel:
Input:
Compressor/Limiter:
EQ Controls:
Output:
Miscellaneous:
Rear Panel:
Tone Generator:
Indicators:
Front Panel:
Microphone
Phantom Power:
Power Requirements:
AC Mains:
1707C:
1715C:
Feedforward Topology
-20 dB to +20 dB
Continuously variable.
(Ref. 100 mVrms on Link
input.)
1:1 to o:1,
Continuously variable.
50 msec to 5 sec.
Continuously variable.
Electronically produced
Buzzer, siren, single-tone
chime, and repeating tone
chime.
All tones are initiated by
remote switch closures.
Rear panel.
l — RCA phono receptacle
I — RCA phono receptacle
3-terminal barrier strip
7-terminal barrier strip
I — RCA phono receptacle
1 — RCA phono receptacle
1 — RCA phono receptacle
Screw Terminals (7)
6 Input Level adjust
I Release Time adjust
(screwdriver slotted)
I Threshold adjust
(screwdriver slotted)
I Compression Ratio adjust
(screwdriver slotted)
1 On/Off Switch
] Bass adjust
1 Treble adjust
1 EQ In/Defeat switch
I Master Level adjust
1 AC Power switch
1 Output Level adjust
(screwdriver slotted)
6 Green LED's, (Nominal
Input Level)
6 Red LED's, (Peak Input
Level)
1 Red LED, Main power
output CLIP)
I AC Power ON
48 VDC @ 200 milliamps
consumption
(Ref. 1 kHz, rated output
with no modules installed
100, 120, 200, 220 or
240 VAC.
165 watts maximum.
100, 120, 200, 220 or
240 VAC.
320 watts maximum.
Power Requirements:
Battery:
1707C:
1715C:
Power Consumption and
Heat Produced:
1707C:
75 watts output:
25 watts output:
1715C:
150 watts output:
50 watts output:
Operating
Temperature Range:
Dimensions: Width:
Height:
Depth:
Net Weight:
1707C:
1715C:
Finish Color:
Included Accessories:
4 — Operating/Service Instruction documents. One
each for the Mainframe, 1780A/AT, 1781 A/AT,
and 1783.
+48 VDC bipolar,
1.5 amps maximum.
+48 VDC bipolar,
3.0 amps maximum.
165 watts consumed.
306 BTU/hour.
130 watts consumed.
357 BTU/hour.
320 watts consumed.
578 BTU/hour.
230 watts consumed.
612 BTU/hour.
Up to 50?C (1227F)
19 inches (48.3 cm)
5/4 inches (13.3 cm)
3 standard rack units.
13 inches (33.0 cm)
25 Ibs. (11.4 kg)
32 Ibs. (14.5 kg)
Black
1 — Shorting Bar (Installed on Direct Output to
OT in).
I — "U" Shorting Bar (Installed on Preamp Out to
Amp In).
4 — Rubber Feet (installed).
I — System Configuration Label installed on top
cover.
1 — International fuse.
] — International 220/240 VAC voltage sticker.
| — International Fuse sticker.
1 — Rack mount hardware kit.
Optional Input Output Accessory Modules:
1780A Mic/Line Input Module.
1780AT Mic/Line Input Module with 10 kQ
bridging transformer installed.
1781A Programmable Input Module.
1781AT Programmable Input Module with 1785A
600 2 to 10 kN isolation transformer installed.
1783 Line Output Module.
1785A 600 € to 10 kQ Input Isolation
Transformer.
1786 600 (2 to 600 (2 Output Isolation
Transformer.
1791 Female XLR Connector.
1792 Male XLR Connector.
1793 Dual RCA Phono Connector.
1794 5—Lug Screw Terminals.
8751A Programmable 14 Band EQ Module.
Altec Lansing continually strives to improve their products
and performance. Therefore, specifications are subject to
change without notice.
4

ELECTRICAL CONNECTIONS FOR THE
1707C/1715C MIXER/POWER AMPLIFIERS
Power Connections (120 Volt, 50/60 Hz)
The mainframe configuration for both mixer/
power amplifiers comes with the power trans-
former's primary line voltage strapped for
120-volt operation from the factory. Refer to
Table | for exact strapping details and other
voltage options.
The numbers in Table | correspond to the
numbered positions on the alternating cur-
rent terminal block connector, which is ad-
jacent to the power transformer. To select
a line voltage, install the colored primary
lead wires into the corresponding numbered
positions on the terminal block.
Table I. AC Line Votage Selection and Strapping Chart
Primary
Line
Voltage
220V
240V
NOTE
Make sure the line voltage corresponds
with the selected line voltage power
rating BEFORE you connect the main-
frame to the alternating current line.
Power Connections (100, 200, 220, or 240
Volt; 50/60 Hz)
You may change the mixer/power amplifier's
120-volt power connection to a 100—, 200—,
220—, or 240— volt power connection by re-
strapping the power transformer's primary
line voltage. Use the following procedure to
change the factory strapping to another line
voltage.
1. If you connected the mixer/power amplifier
to an alternating current power source,
disconnect it.
2. Remove and save the nine screws that
secure the mixer/power amplifier's top
cover. There are two screws near the
bottom of each side, two screws on top
near the rear edge of the front panel, and
three screws at the top edge of the rear
panel. Refer to Figure 1 for details.
Remove 2 screwa
bu 2 screws
3 Áccess Panel
a
AS
Remove 3 Screws
Remove
2 screws
Figure 1. Top-Cover Removal
Transformer Primary Lead Color
WHITE YELLOW | RED | BLUE ORANGE
a | 93 |
HK ANE
3. Locate the voltage selection terminal
block between the side of the chassis and
the power transformer. Refer to Figure 2
for details.
Figure 2. Location of Voltage Selection
Terminal Block
4. While referring to Table I, disconnect the
primary lead wires from the terminal block.
Pull each wire firmly to disengage the push-
on connector. Then reconnect each lead
wire into its designated position on the
terminal block that corresponds to the de-
sired line voltage. Press each connector
to snap into place.
5. Install the appropriate fuse value from
Table II.
Table Il. AC Fuse Selection Chart
AC Line Fuse
AC Line
Voltage
100V
1715C
7.0 A/250 V
7.0 A/250 V
4.0 A/250 V
4.0 A/250 V
4.0 A/250 V
1707C
3.5 A/250 V
3.5 A/250 V
2.0 A/250 V
2.0 A/250 V
2.0 A/250 V
NOTE
Use of fuses other than those listed in
Table tl will VOID THE WARRANTY.
6. If you connected the power transformer 's
primary leads for 200—, 220— or 240— volt
operation, perform steps 7,8, and 9 below
to prevent future confusion and possible
damage to the amplifier. Otherwise, pro-
ceed with step 10 below.
7. Affix the supplied 220/240 VAC label above
the power cord and cover the 120 VAC
silkscreened designation.
8. Affix the 2-amp fuse/1707C, (4-amp/
1715C) label over the original 3.5 amp/
1707C, (7-amp/1715C silkscreened des-
ignation. Refer to Figure 3 for where to
place the fuse label.
Apply Fuse
Label Here B
N
Kë
Apply 220/240
Voltage Label Here
Figure 3. Application of International Stickers
9. Replace the standard AC line fuse with the
2-amp fuse/1707C, (4-amp/1715C)
supplied. You should find the labels and
the fuse enclosed in the plastic bag with
this manual. Refer to Table Il for an AC
fuse selection chart.
10. If you are not installing additional modules
in the mainframe right now, reinstall and
secure the top cover with the nine screws
previously removed in step 2 above.
NOTE
You can buy and install additional mod-
ules into the mixer/power amplifier,
which has six ports that you can con-
figure as input or output modules.

INSTALLING MODULES IN THE
MAINFRAME
For detatled instructions on how to install ad-
ditional input and output modules, you may
order the following operating instruction
manuals from our Order Entrv Department:
P/N 42-02-027720 for the 1781A/AT
Mic/Line Input Modules
P/N 42-02-026653 for the 1780A/AT
Mic/Line Input Modules
P/N 42-02-027721 for the 1783 Line
Out put Module.
1. Remove and save the two screws that
secure the access panel to the top cover.
Refer to figure 1 for details.
2. Plug the input or output module into one
of the six channel positions with the con-
trols facing the rear as shown in Figure 4.
Secure the module with the two screws
provided.
7 Module PCB
A Edge Connector
Praes down firmiy to
Inaure proper seating
with mate connector
on mother board.
ami
OD
Module P d
screws (2)
Figure 4. Module Installation
3. Remove the blank cover panel as shown
in Figure 5. Install the selected connector `
assembly with the screws provided. Plug
the pigtail connector (from the main con-
nector assembly) onto its appropriate male
mating connector on the module's printed
circuit board.
jA Remove two screws
Figure 5. Removal of Blank Cover Panel
4. Onthetopcover isa System Configuration
Label. Use it to indicate the module type,
configuration, and any options for future
reference. Write directly on the label with
a permanent marker. Referto Figure 6 for
a display of this sample label.
INPUT
INPUT
QUTPUT
NONE
MUTE SLAVE
PRIORITV
XFORMER
INPUT
OUTPUT
NONE
MUTE SLAVE
PRIORITV
XFORMER
OUTPUT
NONE
MUTE SLAVE
PRIORITV
XFORMER
FRONT PANEL
NOTE
You may buy connector assemblies to
use for installing additional input/output
modules from ALTEC LANSING.
INPUT
OUTPUT
NONE
MUTE SLAVE
PRIORITY
XFORMER
RVC
INPUT
OUTPUT
NONE
MUTE SLAVE
PRIORITY
XFORMEA
INPUT
OUTPUT
NONE
MUTE SLAVE
PRIORIT Y
XFORMER
Phantom |
Figure 6. System Configuration Label
SHELF OR RACK MOUNTING THE 1707C/
1715C MIXER/POWER AMPLIFIERS
You may shelf mount or rack mount the main-
frame. For shelf or countertop applications,
four rubber feet on the bottom of the chassis
will protect resting surfaces and provide
elevation for air flow underneath the unit. For
rack or cabinet applications, remove the four
rubber feet from the bottom of the chassis.
Then install the unit in the rack with the screws
and shoulder washers provided. The unit must
have 1.75" of blank space both above and
below it.
Ventiliation
The mixer/power amplifier generates minimal
heat during normal use. Although the amount
of generated heat is low, make sure the main-
frame is properly ventilated to prevent an ex-
cessive temperature rise. Because the output
power devices (transistors) are sensitive to
heat, you should not place the amplifier be-
tween other heat generating equipment or
in areas where the ambient temperature ex-
ceeds 50°C (122°F).
lf you mount the mainframe in an equipment
rack or cabinet with other heat producing
6
equipment, provide adequate space between
the units. Otherwise, the equipment may
become too warm.
If a rack or cabinet contains several amplifiers,
you may need to check the ambient air
temperature. To determine the ambient air
temperature, operate the system until the
temperature stabilizes. Measure the ambient
air with a bulb-type thermometer held at the
bottom of the uppermost amplifier.
CAUTION
Dont let the thermometer bulb touch
the metal chassis. The chassis might
be hotter than the ambient air.
CAUTION
If the air temperature exceeds 60*C
(140PF), place the equipment farther
apart or install a blower to provide
air movement within the cabinet.
Make sure you don't block the air-
intake holes located on the bottom of
the chassis or the exhaust holes on
the top cover.

CONFIGURING THE MAINFRAME
The Mainframe's Inner Workings
b DEFEAT
ee
ID
å
DIN
ON
HELVING i
f
EQUALIZER COMP/LIM
SUM 9 c
:
Lé
msn
|
|
:
,
RELAY
REBL THRESHOLD COMP REL O
: BASS TREBLE RATIO TIME | |
Ba EN ene
ns am Be A I AS Ar]
OUTPUT BARRIER
TRANSFORMER ` STRIP
PROTECTION
THERMAL
POWER
MASTER AMPLIFIER
MODULE OUT 'NOMINAL' yoyo ‘PEAK’
100mV RMS
oe LA aN DISPLAY
CH 1-6 | e
INPUT / PUT
U O O MIX QUT
R
Note: Switches
not included L LEVEL
with mainframe
MUTE S
S/T T
O
N
R/T
E
BUZZER G
E TONE GEN
YELP N OUTPUT
LEVEL
(e 100mY RMS
u E | m
LINK OUT (e
PREAMP 0.775V RMS
OUT ra
AMP IN E
AUX OUT (e.
e
POWER
SWITCH
x USER INSTALLED STRAPS
Figure 7 above displays a block diagram of
the mixer/power amplifier mainframe. Study
it carefully. To use the system's full capabil-
ities, you'll need a good understanding of the
inner workings of the mainframe. Brief ex-
planations of how the inside of the mainframe
works follow in the text below.
The signal coming from each additional input
module (like the 1781A, 1781AT, 1780A, or
1780AT) is simultaneously routed to the
mixer/power amplifiers front-panel nominal/
peak LED indicators and to the input channel
level controls. The dual LED nominal/peak
displays are pre-fader and designed to monitor
the output level from the corresponding
input module. The nominal (green) LED in-
dicators have an approximate 10 dB window
over which they will illuminate. This makes
it easy to properly adjust the gain for each
input module while efficiently using the rest
of the system in terms of performance and
headroom.
AC LINE
FUSE
POWER ON x za
VOLTAGE
SELECTOR
POWER
SUPPLY
100/120/200/220/
240VAC 50/60HZ
+
+4BV DC INPUT
Figure 7. Block Diagram of 1707C/1715C
Mixer/Power Amplifiers
The mixer/power amplifier then sums the
signal at the wiper of each input channel
level control into a true virtual ground sum-
ming node or bus. The summing amplifier
has eight input channels — input channels
one through six on the front panel, tone gen-
erator output, and the link input or LINK IN
on the rear panel. The summing amplifier's
output signal drives the link output, or LINK
OUT, located on the rear panel of the main-
frame. The E.Q. and compressor/limiter sec-
tions are in series with each other, as shown
in Figure 7. The compressor/limiter's output
signal drives the preamplifier output, or
PREAMP OUT, located on the rear panel
which then provides the input signal to the
main amplifier section.
The BASS and TREBLE E.Q. controls are
ideallv suited to make adjustments to the
overall response of the mix. The low and high
frequency shelving equalizers provide +12
dB of boost and cut with the maximum boost
occurring at 100 Hz and 10kHz, respectively.
7
OUTPUT
FUSE
VOLTAGE
RAILS
The compressor/limiter section features
- variable release time, compression ratio, and
threshold. The circuit uses a feed-forward
topology that will minimize level differences for
a more nearly constant output level. The
compression ratio can approach —— 1. and the
attack time is fixed at approximately 10 ms.
The main amplifier section protects itself and
the load against radio frequency interference,
spurious oscillatory waveforms, excessive
temperatures, direct current, turn-on/turn-off
transients, and excess voltage/current phase
shift due to reactive loading.
A signal overload circuit monitors the level at
the output stage of the amplifier section. The
front-panel CLIP LED indicator illuminates

when signal levels are high enough to cause
significant output clipping.
A dual slope V-I limiter protects the output
devices. It keeps the output devices operating
within their SOA (safe operating area) as de-
fined by the device manufacturer.
A special integrated circuit function block
monitors the heatsink temperature, power-
supply voltage, and the amplifier's output.
When it detects a problem, it immediately
disengages the output relay.
Output Connections
Make output connections to the seven-ter-
minal barrier strip connector located on the
lower-left side of the mainframe's rear panel.
The 1707C main output connections include
an 8 Q direct output (24.5 vrms) and three
transformer balanced outputs; 4 Q (17.4
vrms), 25 vrms (8.3 Q), and 70.7 vrms (66.6 Q).
The 1715C main output connections include a
4 Q direct output (24.5 vrms) and a 25 vrms
(4.2 Q), an 8 Q (34.6 vrms), and a 70.7 vrms
(33.3 €2 ) balanced transformer output.
Refer to Figure 8 for a display of the direct
output connections and Figure 9 to see the
transformer output connections.
OT an
TOV 25V 4n COM IN +
- lojorofolelo]o
oc A HT t
JH
ql
Figure 8. Direct Output Connections
Insert shorting bar.
Figure 9. Transformer Output Connections
To use a transformer balanced output, install
a U shorting bar between the direct (+) out-
put and the output transformer's input (OT IN).
NOTE
When using the output transformer, you
may use any combination of output
connections as long as the total con-
nected load does not consume more
than 75 watts for the 1707C or 150
watts for the 1715C.
Output Fuse: A fuse in series with the output
ofthe amplifier section protects the amplifier
from excessive current consumption by a
load. If this output fuse blows, replace it only
with a fuse that matches the same type and
rating as silkscreened on the rear panel of
the unit. If the fuse continues to blow, check
the load to see if it shorted or is exceeding
the rated power consumption. If the problem
continues, have a qualified service technician
service the unit.
Mute/Tone Generator Connections
The seven-lug screw terminal connector lo-
cated on the mid-left rear of the mainframe
provides access to the system mute and tone
generator. For connection details, refer to
Figure 10.
S/T BUZZER
External SPST switches
(not included with mainframe}
Figure 10. Mute/Tone Generator Switch
Connections
A switch closure between the mute and
common (COM) terminals will mute any input
modules configured in the s/ave mode. You
can use the remaining switches to select one
of the following sounds:
A single-tone chime (S/T),
A repeating-tone chime (R/T),
A buzzer, or
A yelp (siren).
Forthe duration of atone, the tone generator
automatically mutes any input modules con-
figured in the slave mode.
Output-Level Control: The tone generator's
output-level control is conveniently located
on the rear panel of the mainframe. To in-
crease the tone generator's output level, rotate
the screwdriver-slotted control shaft clock-
wise.
NOTE
Optional External Mute, (connected at
the factory) allows external muting of
the tone generator. If disconnected,
the tone generator cannot be extern-
ally muted.
Resistance Effects of Long-Cable Runs on
Mute/Tone Generator Circuits: Table Ill shows
the maximum allowable cable resistance (total
resistance) that the mixer/power amplifier
can support. Resistances greater than these
values, resulting from excessively long-cable
runs or small gauge wire, may cause the mute
or tone generator circuitry to fail to operate.
Please make sure all cable resistances are
less than the values shown in Table III.
8
Table Ill. Maximum Allowable Cable Resis-
tances
Function Resistance
S/T Chime
R/T Chime
Buzzer
Yelp
Mute
LINK IN/LINK OUT Connections
The LINK IN/LINK OUT phono connectors on
the mid-rear panel of the mainframe permit
you to dynamically link two or more systems
together. If you require more channels, the
1707C/1715C mixer/power amplifiers are fully
compatible with 1700C mixer/preamplifier. For
more information on the 1700C mixer/
preamplifier, you may order the operating
instruction manual (P/N 42-02-029241) or the
specification sheet (P/N 42-07-029242) from
our Order Entry Department.
The signal appearing at the LINK OUT con-
nector is the summation of all input channels
as mixed by the input channel level controls.
LINK IN is a direct input to a system's mixing
amplifier; it's also a seventh input channel.
To link two units together, connect LINK OUT
of system one to LINK IN of system two. Sys-
tem two will now control the mix of up to
twelve input channels. Please refer to Figure
11 for typical linking connections.
NOTE
The LINK OUT signal is not affected by
the compressor/limiter or the E.Q. cir-
cuits.
PREAMP OUT/AMP IN Connections
The PREAMP OUT signal is a mix of all input
channels processed by the compressor/limiter
and tone control circuits. Normally, you would
inserta U shorting bar between the PREAMP
OUT and AMP IN phono connectors on the
rear panel. However, vou can remove the
shorting bar to patch in an external equalizer
or other signal processing device with a pro-
per level match of 0.775 vrms nominal. Figure
12 shows a typical application using an ex-
ternal equalizer or other signal processing
device.

Di ei l
INPUTS 1-6 Fund å
1707C (INPUTS 1-6)
Svstem 1
Link Qut Zone 1 Master
Signal
Flow
INPUTS 7-12 FL
Zone 2
—— (INPUTS 1-12)
——
Svstem 2
Zone 2 Master
INPUTS 1-6 AT-
1707C ——- INPUTS 1-12
System 1 AE
Note: Preamp Out/Amp In jumper removed
in system 1.
Link Out
Link in
INPUTS 7-12
INPUTS 1-12
Master
| Figure 11. Typical Linking Connections
Master E
INPUTS 1-6 $707C !
> E — INPUTS 1-4
Preamp Out Amp ln NE
| Tip Sleeve Tip Sieeve
(| += ag
Signal A |
Flow 2 EŃ
MI Le Cam
A
SP jule
Input Qutput
Externsi
E quallzer/Pracessor
Figure 12. Patching an External Equalizer or
Other Signal Processing Device
AUX OUT Connections
The auxiliary output (AUX OUT) phono con-
nector on the rear panel is wired directly
(internally) to the AMP IN phono connector.
You can use it to drive a second amplifier or a
tape recorder. Please refer to the 1707C/
1715C mixer/power amplifier's block diagram
shown in Figure 7.
Batterv Input Connections
You can power a system from the battery input
connector for auxiliary operation or standby
switchover. The battery input connector is the
three-terminal barrier strip located on the
upper-left rear panel of the mainframe. The
system requires two +48V DC battery power
sources.
To connect the battery backup system to the
three-terminal barrier strip, follow the three
steps shown in Figure 13.
Step O
Remove Cisar Plastic Cover.
Siep (2)
Connect DC Power Sources
ss Shown.
Step (3)
Re-inetail Clear Plastic
Protective Cover.
DC Power Sources
Figure 13. Battery Input Connections

FRONT/REAR-PANELS CONTROLS, SWITCHES, INDICATORS, AND CONNECTORS
Figure 14 below displays the front panel on the 1707C mixer/power amplifier with numbers that point
out each control. indicator. and switch. You can find the corresponding number and name/description
of each control. switch, or indicator in the text below Figure 14. These controls. indicators, and
switches are identical on the 1715C.
Figure 14. Front-Panel Control, Switches, and Indicators for the 1707C
NT
item Name |» Function/Description
1 POWER Switch Applies primary power. Two-positton push-push switch
for on/off mode.
illuminates red display on POWER switch when you
turn on power.
INPUTS
Continuously variable potentiometers graduated from
æ to O dB. You can increase or decrease level
for each corresponding input channel. Rotate clockwise
to increase level and counterclockwise to decrease
level.
INPUT LEVEL
Displays nominal (green) and peak (red) indication for
each channel.
COMPRESSOR/LIMITER
Continuously variable potentiometer. Determines the
level at which limiting begins.
2 ON LED Indicator
CH 1-6 Controls
4 Green/Red Dual LED
indicators
5
THRESHOLD Control
Continuously variable potentiometer. Determines the
time required for the system to return to normal after
signal falls below threshold.
6 RELEASE TIME Control
Continuously variable potentiometer. Determines the
amount of limiting that will occur when the input signal
level exceeds the threshold, as set by the THRESHOLD
control.
COMPRESSION RATIO
Control
Places compressor/limiter circuit in or out of the
signal path.
OUTPUT
Continuously variable potentiometer. Provides boost
or cut in bass response. You can obtain normal or flat
response at a zero setting. Rotate clockwise to boost
response or counterclockwise to cut response.
ON/OFF Switch
W BASS Control
Continuously variable potentiometer. Provides boost
or cut in treble response. You can obtain normal or
flat response at a zero setting. Rotate clockwise to
boost response or counterclockwise to cut response.
TREBLE Control
BASS and TREBLE controls when appropriate for
application, such as Acousta-Voicing. EQ IN connects
the BASS and TREBLE controls.
MASTER Level Control Continuously variable potentiometer graduated from
^ to O dB. Use it to simultaneously increase or de-
crease all input channels. Rotate clockwise to increase
7
10
11 EQ IN/DEFEAT Switch Two-position switch . DEFEAT position disconnects
12
level or counterclockwise to decrease level.
13
: CLIP LED Indicator Illuminates when an internal signal overload circuit
detects high output signal levels that may cause output
clipping.
10
INITIAL SETUP AND OPERATION OF
MAINFRAME WITH MODULES INSTALLED
Initial Setup of an input Module
You can buy and install the following input
modules from ALTEC LANSING:
The 1781A programmable input module. The
1781AT programmable input module with
1785A input isolation transformer, and
The 1780A and 1780AT mic/line input
modules.
To initially set up an input module, follow
these steps:
1. Rotate the input module's gain control to
the 12:00 o'clock (MID) position for plan-
ned microphone inputs or to the MIN (fully
counterclockwise) position for line-level
inputs. Ifthe input type is unknown, rotate
the gain control to the MIN position.
2. Rotate the high-cut (HF) filter to the FLAT
position.
3. Rotate the low-cut (LF) filter to the FLAT
position.
Initial Setup of an Output Module
You can buy the 1783 line output module
from ALTEC LANSING. This module can be
installed with or without the optional 1786
output isolation transformer (also available
from Altec Lansing).
To initially set up an output module, rotate
the output module's output level control
(labeled GAIN on the rear panel) to the MIN
position.
Initial Setup of the Mainframe
1. Rotate the MASTER output level control
on the front panel of the mainframe to the
co position (fully counterclockwise).
2. Setthe compressor/limiter ON/OFF switch
to the OFF position.
3. Setthetone control EQ IN/DEFEAT switch
to the DEFEAT position.
Operating the 1707C/1715C Mixer/Power
Amplifiers
1. Connect a source representative of the
type of input signal to one of the input
module positions, if any. Slowly rotate the
input module's gain control clockwise un-
til the mixer/power amplifier's green LED
display (—10 dB) on the input-level front-
panel section fully illuminates. This is the
nominal level for providing the most effi-
cient performance and headroom.
The mixer/power amplifier's red LED dis-
play may briefly illuminate on signal
peaks. This is permissible as long as it
does not flash more than fifty percent of
the time. If it does, reduce the gain of the
input module by rotating its gain control
counterclockwise or use an external pad.

Figure 15 below displays the rear panel on the 1707C mixer/power amplifier with numbers that point
out each connector or control. You can find the corresponding number and name/description of each
connector or control in the text below Figure 15. These connectors and controls are identical on the
1715C.
Figure 15. Rear-Panel Control and Connectors for the 1707C
| [ |
c dd
N x i
Permits access to the screwdriver adjustable controls
on the modules.
Access Holes
Covers connector mounting holes. Protects against
internal voltages when not using port and connector.
Blank Cover Panel
Combine two units together by connecting LINK OUT
of system one to LINK IN of system two. This is an
RCA-type phono connector.
LINK OUT Connector
Provides a direct input to the amplifier. This is an RCA-
type phono connector (ref. 1 kHz, 100 mvrms).
LINK IN Connector
PREAMP OUT Connector
Use to patch auxiliary equipment between unit's mixer
and power amplifier. PREAMP OUT is normally strapped
to AMP IN. The PREAMP OUT connector precedes the
front-panel MASTER level control. This is an RCA-type
phono connector.
AMP IN Connector Provides a direct input to the amplifier. This is an RCA-
type phono connector (ref. 1 kHz, .775 mvrms).
Provides an auxiliary output of the signal appearing
at the amplifier's input. This is an RCA-type phono
connector.
AUX OUT Connector
Permits connection of external switches to operate
the system's mute and tone generator circuits.
Seven-Lug Screw Terminal
Connector.
OUTPUT LEVEL Control
Increase the output level of the tone generator by
rotating the screwdriver-slotted control shaft
clockwise. To decrease the output level, rotate it
counterclockwise.
Permits connection of various loads to the
amplifier.
Seven-Terminal Barrier
Strip Connector
U Shorting Strip
Connects output of amplifier to input of output
transformer. When in place, use only the transformer
outputs.
Protects load against excessive current from
amplifier. Replace only with the same fuse type
and power rating.
OUTPUT FUSE
Battery Input Connector Use to power system from battery supply for auxiliary
operation or standby switchover. Requires one +48V DC
battery power source, 1.5 amps maximum for the
1707C and 3 amps for ihe 1715C.
Protects against excessive current drain from an
alternating current source. Replace only with same
fuse type and power rating.
14 AC FUSE
The ground terminal lets you connect auxiliary
equipment to the mainframe.
15 GND
11
NOTE
The LED display precedes each front-
panel input-level control. As a result,
it will always indicate the nominal and
peak levels regardless of input channel
settings. Please refer to the mainframe
block diagram shown in Figure 7.
Once the gain is set for each input module
channel, rotate the front-panel input-level
channel controls (CH 1-6) on the mixer/
power amplifier to their 12:00 o clock
(MID) position. Slowly increase the MAS-
TER output level control on the front of
the mainframe until you hear a normal
operating level through the loudspeaker
system. Then readjust the input-level
channel controls slightly for the destred
mix or blend of signals.
. Adjust the high-cut (HF) and low-cut (LF)
filters on the input module as needed for
the desired response. The widest possible
bandwidth occurs when you rotate both of
these controls to the FLAT position. This
is the best setting for music. However, in
speech-only channels, you should limit
the bandwidth to help reduce noise and
system feedback.
. To use the mixer/power amplifier's output
tone-control section, move the two-posi-
tion EQ IN/DEFEAT slide switch to the
EQ IN position. Then adjust the BASS
and TREBLE controls for the desired re-
sponse. From a center or 12:00 o'clock
(MID) position, rotate either control clock-
wise to boost response or counterclock-
wise to cut response.
If using the tone-control section is inap-
propriate for current applications, such as
Acousta-Voicing, move the EQ IN/DE-
FEAT slide switch to the DEFEAT position.
This disconnects the BASS and TREBLE
controls.
To use the compressor/limiter section,
follow this procedure:
Move the slide ON/OFF switch to the ON
position.
Rotate the RELEASE TIME control to its
maximum position (full clockwise).
Rotate the COMPRESSION RATIO con-
trol to minimum position (full counter-
clockwise).
Rotate the THRESHOLD control to its
12:00 o'clock (MID) position.
Begin increasing the compressor/limiter
bv rotating the COMPRESSION RATIO
control clockwise until vou achieve the
desired amount of compression or limiting.
Since the amount of compression or
limiting depends on the incoming signal
level, you may need to readjust the
THRESHOLD control. To lower the trig-
gering threshold, rotate the THRESHOLD
control counterclockwise. If the system re-
quires a higher incoming signal level to
trigger the compressor/limiter, raise the
threshold bv rotating the THRESHOLD
control clockwise.

NOTE
A high compression ratio and a low
threshold setting may decrease the
system's apparent loudness since peak
signals and parts of the nominal signal
may lie above the threshold. You can
correct this by raising the threshold
level; just rotate the THRESHOLD
control clockwise.
If you installed the 1783 line output
module, adjust the output level control on
the 1783 for the desired output level. The
higher the output level, the better the
signal-to-noise ratio. However, too high a
level reduces the available headroom and
may cause premature clipping.
NOTE
tf you set the 1783'3 output level con-
trol at its MAX (full clockwise) level, the
output level is +8dBm. However, this
level only applies if you use a 100
mvrms reference level on the input of
the output module from the mix output
bus. lt also only applies if you have a
balanced 600 Q load.
12
WARNING
Repair performed by other than auth-
orized warranty stations (dealers) or
qualified service personnel shall void
the warranty period of this unit. To
avoid loss of warranty, see your near-
est ALTEC LANSING authorized deal-
er. You can also call ALTEC LANSING
CUSTOMER SERVICE authorized deal-
er. You can also call ALTEC LANSING
CUSTOMER SERVICE directly at
405/324-5311, FAX [phone], or
write:
10500 W. RENO
OKLAHOMA CITY, OK 73128 U.S.A.

ALTEC
the sound of experrence
1707C/1715C
MIXER/POWER AMPLIFIERS
SERVICE INSTRUCTIONS
xxx CAUTION * **
No user-serviceable parts are inside: you may en-
counter hazardous voltage within the chassis. Ser-
vicing information contained within this document
is for use only by ALTEC LANSING Corp. authorized
warranty stations and qualified service personnel. To
avoid electric shock, DO NOT perform any servicing
other than that contained in the Operating Instruc-
tions unless you're qualified to do so. Refer all ser-
vicing to qualified service personnel.

SERVICE INFORMATION
WARNING
ALTEC LANSING recommends that
you do not modify its products. Such
modifications shall be at the sole ex-
pense of the person(s) or company re-
sponsible. Any damage to persons or
property resulting therefrom shall not be
covered under warranty or otherwise.
Power Amplifier Bias Adjustment
NOTE
This adjustment requires a DC volt-
meter.
Figure 16, shown on the gatefold, is the
schematic of the mainframe. You'll need
trimpot SVR102, provided in this system's
package, to set the bias of the amplifier. You
should set the bias current to approximately 20
milliamps DC. To set the bias, use a battery-
powered DC voltmeter capable of reading in
the millivolt range and follow the procedures
outlined below. If you must use an AC-pow-
ered voltmeter, floatthe AC ground wire using
the appropriate adapter.
1. With the unit unplugged, remove the top
cover from the unit to expose the main
circuit board. See Figure 1 on page 5
for how to remove the top cover.
2. Connect the rated load impedance to the
direct output of the mixer/power amplifier
(8 Q for the 1707C, 4 Q for the 1715C).
3. Attach RED probe lead from the DC
voltmeter to the junction of R130 (0.27 Q
emiter resistor) and the emitter of Q117.
Refer to figure 16.
4 Attach the BLACK probe lead to the junc-
tion of R130 (0.27 (2 emitter resistor) and
the anode of D403.
5. Locate SVR102 on the main circuit board.
Apply power and adjust SVR102 for a
reading of approximately 5.5 millivolts.
Power Amplifier DC Offset Adjustment
NOTE
This adjustment requires a DC volt-
meter.
1. Set the POWER switch to the OFF posi-
tion. Rotate the MASTER level control
fully counterclockwise to the e position.
2. Connectthe rated load impedance for the
unit to the direct output (8 O for the 1707C,
4 Q for the 1715C). Connect the DC volt-
meter across the load.
3. Locate SVR101 on the main circuit board.
Apply power and adjust SVR101 for a
reading of 0.00 VDC+10mV DC.
14
Parts Ordering
To order replacement parts, refer to the parts
list. If part is not included on parts list, note
the component designator from the schem-
atic (or printed circuit board) and the com-
ponent's description. Then call 405/324-5311,
FAX [phone], or write:
ALTEC LANSING Replacement
Electronic Parts
P.O. Box 26105
Oklahoma Citv, OK 73126-0105 U.S.A.
Factorv Service
If the unit requires factorv service, ship the
unit prepaid in the original carton (or a well-
packed carton) to the following address:
ALTEC LANSING Customer
Service/Repair
10500 W. Reno
Oklahoma City, OK 73128 U.S.A.
Please enclose a note that provides the fol-
lowing information:
Any details describing the problem, and
the conditions under which the problem
occurred, such as where used, how used,
and so forth.
Failure to enclose any helpful information
may delay the processing of your service
order.
Technical Assistance
For applications assistance or other
technical information, call 405-324-5311,
FAX [phone], or write:
ALTEC LANSING Technical
Assistance
P.O. Box 26105
Oklahoma City, OK 73126-0105 U.S.A.