1662A
Mic/Line Mixer
Power
Altec Lansing Professional
1000 W. Wilshire Blvd. Suite 362
Oklahoma City, OK 73116 USA
A division of Altec Lansing Technologies Inc, Milford PA 18337-0277 Made In USA
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Operating Manual -1662A Mic/Line Mixer
1. INTRODUCTION
they were carefully designed to reduce to
minimum the possibility of transportation
damage should the unit again require packing
and shipping. In the event that damage has
occurred, immediately notify your dealer so that
a written claim to cover the damages can be
initiated.
Congratulations on your purchase of an
Altec Lansing 1662A mic/line mixer, a
professional, studio quality solution to everday
mixing needs. The 1662A features six mic/line
inputs with mic input pad, TRS insert points, and
+48V phantom power. Each channel has up to
60dB input gain, separate treble and bass
controls, level, and an output channel assign
switch for sending any channel to either or both
outputs. Stereo sum inputs are provided for
adding typical program audio sources from DVD,
CD, tape, etc. A full 11 segment LED array
indicates stereo output level.
The right to any claim against a public
carrier can be forfeited if the carrier is not
notified promptly and if the shipping carton and
packing materials are not available for
inspection by the carrier. Save all packing
materials until the claim has been settled.
Mic/line inputs and main outputs use
Euroblock connectors, allowing bare wire to be
easily connected to the mixer without soldering.
The 1662A mixer uses professional quality 16mm
metal shaft potentiometers for greater accuracy
and long life.
3. AC POWER REQUIREMENTS
The 1662A mixer will perform normally
from 93 to 125 volts AC, 50-60Hz (some export
models are wired for 240 Volts and are labeled
accordingly). Use only properly grounded AC
receptacles. To reduce the risk of ground loop
hum, use a central point for system AC power
distribution. In the event of an internal fuse
failure, refer this unit to a qualified service
technician for fuse replacement using only the
same type fuse, 0.5A Bussman AGC-1/2 or
equivalent. Power consumption is less than 20
watts.
2. UNPACKING
As a part of our system of quality control,
every Altec Lansing product is carefully
inspected before leaving the factory to ensure
flawless appearance. After unpacking, please
inspect for any physical damage. Save the
shipping carton and all packing materials , as
The lightning flash with arrowhead
symbol, within an equilateral tri-
angle, is intended to alert the user
to the presence of uninsulated
"dangerous voltage" within the
product's enclosure that may be of
sufficient magnitude to constitute
a risk of electric shock to persons.
The exclamation point within an
eqilateral triangle is intended to
alert the user to the presence of
important operating and mainte-
nance instructions in the literature
accompanying the device.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE
COVER. NO USER SERVICEABLE PARTS INSIDE. REFER SERVIC-
ING TO QUALIFIED SERVICE PERSONNEL.
TO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK,
DO NOT EXPOSE THIS APPlIANCE TO RAIN OR MOISTURE.
TO REDUCE THE RISK OF FIRE, REPLACE ONLY WITH SAME
TYPE FUSE. REFER REPLACEMENT TO QUALIFIED SERVICE
PERSONNEL.
WARNING:
THIS APPARATUS MUST BE EARTHED
3
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Operating Manual -1662A Mic/Line Mixer
4. FRONT PANEL CONTROLS
4.1 Input Gain Switch
4.4 Input Assign Switch
This switch selects the output routing for
each input channel. Each input can be routed to
Output A, B, or both.
This three position switch sets the
operating level of the input preamp to +20db,
+40dB, or +60dB. Best signal to noise ratio is
obtained with higher gain settings. It is
therefore desirable to set the gain switch as high
as possible while still leaving 20dB of headroom
for signal peaks. Line level inputs will likely use
a setting of +20dB, while mic inputs generally
require a setting of +40dB for close mic
applications, and +60dB for quieter signals. If a
channel's clip LED is blinking, first turn down
that channel's level control. If the clip LED is
still flashing, turn down the input gain.
4.5 Input Level Control
This knob adjusts the level of each
channel. If a channel's level control is always
turned up to 9 or more, try increasing the gain
first. Conversely, if the level control is
consistently turned down to 1 or less, decrease
the gain setting first. Remember that the gain
setting should be set as high as possible while
still allowing 20dB of headroom.
4.6 Output Level Controls
4.2 Clip Indicator
These two controls determine the signal
level to the "A" and "B" outputs. They are used
to drive power amplifiers for the main
loudspeakers, or to connect to a stereo
recording device.
Input Clip LEDs are peak sensitive and
monitor all critical points within the input
channel. The clip LED turns on whenever any
portion of the audio path within the input
channel reaches a level 3 dB below actual
clipping. Clipping in the 1662A occurs at +23dB.
4.7 Output Meters
A pair of peak reading 11 segment LED
meters are used to indicate stereo output level
in VU. 0 VU is equivalent to +4 dBu (1.228Vrms).
4.3 Treble and Bass Controls
These controls are used for broad EQ
changes to each input channel. Channel EQ
consists of a high shelf control (treble) at 8KHz,
and a 90Hz low shelf control (bass). EQ boost or
cut is 12dB at these frequencies.
Green LED's are used below 0 VU, yellow
above 0 VU and two red LED's indicate clipping.
The clip LED's turn on 3dB below actual
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Operating Manual -1662A Mic/Line Mixer
Power
clipping, detecting excessive signal level on any
critical audio path within the master section. If
all outputs are turned down and there is still
clipping, then one or more inputs needs to be
turned down.
construction. This type of cable should be used
for all portable applications. Snake cables
containing multiple shielded pairs can be used
for a permanent installation, but must be
handled very carefully because the leads tend to
be fragile, and a broken conductor is difficult to
repair.
4.8 Phantom Power LED
The phantom power switch is on the back
panel. When the switch is pressed in, the LED is
lit and +48VDC is applied to all six mic inputs for
use with condenser microphones. If there is a
mix of both condenser and dynamic
microphones, the phantom power will not affect
the operation of the most dynamic mics. The
phantom power voltage ramps up gradually to
minimize any turn-on "pops".
If low level and high level lines are run
parallel for long distances, crosstalk may occur.
In fact, the crosstalk (signal leakage between
cables) can cause an electronic feedback loop,
oscillation, and possibly damage to the
equipment. To minimize crosstalk, physically
separate low level (microphone) cables from
speaker cables by the greatest feasible distance.
At any point where cables meet, run low level
cables perpendicular to high level or speaker
cables. If low and high level or speaker cables
must be run parallel and in close proximity to
one another, they should be bundled separately.
In a permanent installation, avoid running
speaker cables and mic cable through the same
conduit pipe.
5. CONNECTORS AND CABLES
The 1662A mixer is fitted with three types
of audio connectors: 3-pin Euroblock assemblies
are used for mic/line inputs and main outputs, 1/
4" tip-ring-sleeve (TRS) phone jacks are used for
individual channel insert points, and RCA jacks
are used for sum inputs.
Two-conductor (twisted pair) shielded
cable is best for all audio connections that use
Euroblock assemblies. Belden No. 8412 or its
equivalent is an excellent cable due to its heavy
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Operating Manual -1662A Mic/Line Mixer
6. REAR PANEL FEATURES
6.1 Microphone Input
6.3 Channel TRS Insert
A 1/4" stereo phone jack insert point
allows a device such as a remote level
controller, graphic equalizer, noise gate,
compressor/limiter, or direct out recording
device to be used with one or more input
channels.
The 1662A microphone input is an active
balanced type with a nominal impedance of
1200 ohms. Its noise performance is best with a
200 ohm microphone. The mic input connector
is a 3-pin Euroblock with the shield on (G), the
(+) in-phase connection on (+), and the (-) out-
of-phase connection on (-). If the input is
unbalanced, or single ended (meaning there is
only one signal wire with a shield) connect the
signal wire to (+), and connect the shield to
both (-) and (G).
The 1662A TRS (tip-ring-sleeve) insert
jacks use the tip for output and ring for the
returning input. These signals will be
unbalanced, so cable length should be at a
minimum to maintain low noise.
To use the TRS insert as a Direct Line
Output (pre EQ) for recording individual
channels, make a special cable with tip and ring
connected at the 1662A end and a tip-sleeve
mono plug at the other end. Connecting tip
and ring at the mixer insert jack is necessary for
uninterrupted signal within the mixer when
using direct line outputs.
G
-
+
Euroblock
Connector
System
G
Tip
Ring
Sleeve (Ground)
-
+
Stereo Phone Plug
6.2 Input Pad
6.4 Sum Inputs
The input pad is a 20dB attenuation
switch for extremely loud microphone or line
level inputs. It should normally be left in the
"out" position for best signal to noise ratio, but
can be used when the input is being clipped
with the gain and level control at minimum.
The RCA sum inputs on channels five and
six are typically used for auxillary audio sources
such as a disc or tape player, summing a stereo
source into a mono signal for each channel's
input. Using the sum inputs does not prevent
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Operating Manual -1662A Mic/Line Mixer
the use of mic inputs on channels five or six, but
only one level controls both the mic and RCA
inputs. The RCA sum inputs have a nominal
operating level of -10dBu to match most
consumer audio sources.
channel gain and/or press in the pad switch on the
rear panel. There are many gain adjustments in
the mixer itself and probably several others in
other system components which makes it possible
to overdrive an input section and then incorrectly
try to reduce the gain of the output section. The
best way to approach setting gains is to establish
the operating level of input stages first by setting
their gain as high as possible but leaving about
20dB of headroom for loud peaks, then move on to
set the master gain to produce a good meter
reading. Proceed to set the gain of equalizers,
limiters, crossovers, and amplifiers following the
mixer in the same manner, always working toward
the later stages of the system.
6.5 Outputs
The Euroblock "A" and "B" outputs are
controlled by the output level master controls.
They are active servo-balanced with a nominal
operating level of +4dBu into any load, and are
capable of driving long lines. Outputs can be
used balanced or unbalanced. For unbalanced
output, connect the shield to both (-) and (G).
6.6 +48V Phantom Power Switch
7.3 Excessive Noise
This switch applies +48VDC to all six mic
inputs for condenser microphones. Phantom
power will not affect most dynamic mics, which
may be used along with condenser mics.
If the noise is in the form of hiss, the
problem is usually due to an input stage set for
insufficient gain and then compensating for it
by increasing the level. Try increasing gain and
reducing level. Also, check that the -20dB rear
panel pad switch is not unnecessarily enabled.
7. TROUBLESHOOTING TIPS
7.1 No Sound
7.4 Excessive hum
Check the AC power. Is the power switch
on? Check the level meters. If they are
operating, the problem is between the mixer
and the later components in the system. If there
is no meter activity, check to see that you really
have an input signal and that it is on the desired
channel.
This is usually caused by "ground loops"
in the system wiring. A complex sound system
with many sources separated by significant
distance and using several power outlets has
many opportunities for this problem to occur. If
possible, every component in the system should
be plugged into the same AC circuit with a
common ground. Use balanced input and
output connections between widely separated
components.
7.2 Distorted Sound
Something is being overdriven in the signal
path. If the clip indicators are active, reduce the
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Operating Manual -1662A Mic/Line Mixer
8. TYPICAL APPLICATION:
VCR, CD, DVD Player
Audio Output
In the setup shown here,
the 1662A is used to mix typical
sound sources that might be found
in a church, small club, gym, school
theater or similar environment.
Channels 1-4 are used for vocal
microphones, while the remaining
two channels are used for stereo
program tracks. "B" output is used
for main loudspeakers, and "A"
output is used for speakers in
another location, such as ceiling
speakers in a hallway.
Accompaniment Tracks
Cassette Player
Sum Inputs to
Channels 5 & 6
Four Vocal
Mic Inputs
1662A
Mic/Line
Mixer
Hallway
Ceiling
Speakers
70 Volt Distributed
Sound System Amp
EQ,
Limiter,
Crossover,
Amplifier,
etc.
Full Range
Loudspeaker
1662A Small Sound Reinforcement System
9. DIMENSIONS:
3.50 (88.9)
3.25 (82.5)
Altec Lansing 1662A
0.25 (6.3)
0.00
6.50 (165)
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Operating Manual -1662A Mic/Line Mixer
PEAK INDICATORS
10. SPECIFICATIONS
Peak Clip indicator on each input channel and left and right
outputs, illuminates 3dB below clipping
DISTORTION
THD at +4 dBu, 20Hz-20KHz . . . . . . . . . . . . . . . . . . . . . <0.01%
IMD (SMPTE) at +4dBu . . . . . . . . . . . . . . . . . . . . . . . . . <0.01%
PHANTOM POWER
+48 VDC applied to all Mic Inputs, switchable on rear panel.
Maximum total current draw = 60mA. Maximum single
channel current draw = 10mA. Gradual power-up and down
to eliminate "pops".
HUM & NOISE (20Hz-20KHz at max preamp gain)
Equivalent input hum and noise . . . . . . . . . . . . . . . <-127dBu
Residual output noise,
WEIGHT
all levels at minimum . . . . . . . . . . . . . . . . . . . . . . . . . . <-98dBu
Residual output noise, master at nominal,
12 lbs. (5.5kg) Shipping
10 lbs. (4.5kg) Net
all channel levels at minimum . . . . . . . . . . . . . . . . . . <-95dBu
POWER REQUIREMENTS
MAXIMUM VOLTAGE GAIN ( 2dB)
120 VAC nominal, 93 VAC minimum, 50-60 Hz,
20 watts (240 VAC available)
MASTER
Mic/Line Input to Master Outputs . . . . . . . . . . . . . . . . . +84dB
Sum Input to Master Output . . . . . . . . . . . . . . . . . . . . . +24dB
*unless otherwise stated, specification conditions are: 150Ω
source, Gain switch set at "+40", all other controls set at
nominal.
MAXIMUM LEVELS
Input level, +20dB gain, pad in . . . . . . . . . . . . . . . . . . +22dBu
RCA input level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +10dBu
Output level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +23dBu
11. WARRANTY INFORMATION
The unit you have just purchased is protected by
a limited five-year warranty . For warranty service or to
obtain a return RMA number, please call Altec Lansing
technical services at 405-848-3108. Fill out the informa-
tion below for your records.
FREQUENCY RESPONSE
20Hz-20KHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.5/-1.0dB
EQUALIZATION (shelving)
Model Number _______________________________
Serial Number ________________________________
Dealer ________________________________________
Bass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12dB at 90Hz
Treble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12dB at 8KHz
CROSSTALK
______________________________________________
Date of Purchase ______________________________
Dealer’s Address ______________________________
______________________________________________
______________________________________________
Dealer’s Phone ________________________________
Salesperson ___________________________________
______________________________________________
Adjacent inputs, 20Hz-20KHz . . . . . . . . . . . . . . . . . . . . <-70dB
VU METERS
Stereo outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . -21 to +6 VU
0VU = +4dBu
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Operating Manual -1662A Mic/Line Mixer
12. 1662A Block Diagram
Input Channels 1-4
Input
Clip
Indicator
Output
Meters
Mic Gain
+20 +40 +60
Output A
+
-
Channel
Level
+12dB max
0dB Mid
Output
Level
+12dB max
+1.6dB Mid
Servo-
Balanced
Output
Mic
Input
Mic
Preamp
Output
Assign
EQ
S
G
A
A+B
B
-20dB
Pad
Bass Treble
Level
Level
Insert
Point
Output
Meters
Output B
Input Channels 5-6
Input
Clip
Indicator
+
-
Output
Level
Servo-
Balanced
Output
Mic Gain
+20 +40 +60
S
+12dB max
+1.6dB Mid
G
Level
Channel
Level
+12dB max
Mic
Input
Mic
Preamp
Output
Assign
EQ
0dB Mid
A
A+B
B
-20dB
Pad
Bass Treble
Level
Insert
Point
S
R
L
Sum
Input
Phantom
Power
+48V To All
Mic Inputs
10
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Operating Manual -1662A Mic/Line Mixer
11
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Operating Manual -1662A Mic/Line Mixer
Altec Lansing Professional
1000 W. Wilshire Blvd. Suite 362
Oklahoma City, OK 73116 USA
A division of Altec Lansing Technologies Inc, Milford PA 18337-0277 Made In USA
Printed in USA
1662A-0 0503
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