Altec Lansing Musical Instrument 1662A User Manual

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  
4
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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  
5
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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  
7
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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)  
8
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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: 150  
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  
9
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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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