CAM8-Series
Models CAM8, CAM8PRO
Installation and Use Manual
© 2000 Bogen Communications, Inc.
All rights reserved.
54-2034-01C 0508
© 2000 Bogen Communications, Inc.
All Rights Reserved.
Notice
Every effort was made to ensure that the information in this
guide was complete and accurate at the time of printing.
However, this information is subject to change.
Important Safety Information
Always follow these basic safety precautions when installing
and using the unit:
1. Read all instructions before installing or operating the
unit.
2. Follow all warnings and instructions marked on the
product.
3. DO NOT block or cover the ventilation slots and
openings.They prevent the product from overheating.
DO NOT place the product in a separate enclosure or
cabinet, unless proper ventilation is provided.
4. Never spill liquid on the product or drop objects into the
ventilation slots and openings. Doing so may result in
serious damage to the components.
5. Repair or service must be performed by a factory
authorized repair facility.
6. The product is provided with a UL-CSA approved, 3-wire
ground type plug.This is a safety feature. DO NOT defeat
the safety purpose of the grounding type plug. DO NOT
staple or otherwise attach the AC power supply cord to
building surfaces.
7. DO NOT use the product near water or in a wet or
damp place (such as a wet basement).
8. DO NOT use extension cords.The product must be
installed within 6 feet of a grounded outlet receptacle.
9. DO NOT install telephone wiring during a lightning
storm.
10. DO NOT install telephone jacks in a wet location unless
the jack is specifically designed for wet locations.
11. Never touch uninsulated wires or terminals, unless the
line has been disconnected at the paging or controller
interface.
12. Use caution when installing or modifying paging or
control lines.
Maintenance & Service
Caution
There are no user-serviceable parts within the unit. Have all internal servicing performed by a qualified technician. The warranty
will become void if repairs are made by other than the Bogen
Service Department or an authorized service agency.
Our Applications Engineering Department is available to help
you troubleshoot problems with your Bogen equipment.
Engineers are available from 8:30 AM to 6:00 PM, Eastern
Standard Time. Phone 1-800-999-2809.
Service can be obtained from our factory service department.
No merchandise may be returned for repair without prior
written authorization. Please contact our factory service
department at 1-800-999-2809 for a RA number. Only mer-
chandise specified in the return authorization form can be
returned to obtain warranty or non-warranty repair. When
shipping your unit, pack your system well using the original
shipping carton or a similar container and filler material to
prevent damage in transit. Send the unit fully insured and prepaid via UPS or other responsible carrier.
Domestic and International Listings
UL and CSA Listed.
Page 2 of 32
Contents
INTRODUCTION............................................................................................................................................................................................4
Safety Instructions ................................................................................................................................................................................5
QUICK START ..................................................................................................................................................................................................6
PANEL DESCRIPTIONS ..........................................................................................................................................................................7-9
CAM8 Front Panel................................................................................................................................................................................7
CAM8PRO Front Panel ......................................................................................................................................................................8
CAM8/CAM8PRO Rear Panel ..........................................................................................................................................................9
Helpful Hints........................................................................................................................................................................................10
INSTALLATION ......................................................................................................................................................................................11-12
OPERATION ............................................................................................................................................................................................13-20
Troubleshooting Gain Structure ....................................................................................................................................................14
Recommended Input Wiring Methods ..........................................................................................................................................15
Fine Tuning............................................................................................................................................................................................16
Compressor/Limiter ..........................................................................................................................................................................17
Special Features Activation ..............................................................................................................................................................18
Jumper Options ..................................................................................................................................................................................19
LINKING ....................................................................................................................................................................................................20-22
Simple Linking......................................................................................................................................................................................21
Complex Linking ................................................................................................................................................................................22
AC Power Connection......................................................................................................................................................................23
Technical Support ..............................................................................................................................................................................23
TROUBLESHOOTING TIPS ..................................................................................................................................................................24
GLOSSARY ......................................................................................................................................................................................................25
TECHNICAL INFORMATION ........................................................................................................................................................26-28
Auxiliary Circuits ................................................................................................................................................................................27
Block Diagram ....................................................................................................................................................................................28
WARRANTY....................................................................................................................................................................................................29
Page 3 of 32
Introduction
This manual covers installation for both the CAM8 and CAM8PRO.They were manufactured
to ensure the highest quality audio signal production and control, while still incorporating simple-to-use features.
This manual is designed to familiarize you with the features of your new Bogen CAM8-Series
mixer and to guide you through its installation and operation.
CAM8-Series
Page 4 of 32
Safety Instructions
Bogen’s CAM8-Series mixers are electrical equipment, so take all the precautions usually
taken when installing and using electrical equipment (see inside front cover).To protect both
the users and the equipment, pay particular attention to:
• Grounding - Make sure both the mixer and the devices connected to it are
properly grounded.
• Power Supply - Use only the power supply provided or one that meets the
manufacturer’s specifications.
• Cords and Cables - Route all cords and cables so that they will not be tripping
hazards or subject to damage (from being run over or pinched) that could cause
them to become shock hazards. Pay particular attention to cords at plugs,
convenience receptacles, and the point where they enter the mixer.
Page 5 of 32
Quick Start
1. Unpack and Connect (See page 11 for more details).
A. Check mixer for shipping damage.
Rack Mounting: To mount the CAM8 and CAM8PRO to a 19” rack, lift the unit up
to the front of the rack and secure it to the front of the rack with the necessary
screws (not included with this unit).
B. If special features (see page 18) are to be used, they must be programmed before
mixer is mounted.
C.Turn off both mixer and amplifier and turn all volume controls to zero.
D. Connect inputs and set the input pad switch for each channel at the appropriate
level (either MIC or line). Make sure that the bus selector is set for Main Out.
E. Connect output(s) and set the main output pad switch at the appropriate level
(either MIC or line). (Auxiliary output is line-level only.)
2. Power and Set Up (See pages 11-15 for details.)
A. Connect mixer AC power supply.
B.Turn volume controls down, then power up mixer and amplifier.
Note: Mixer will produce signal transients on power up and power down. Always
turn the mixer on first before turning on the amplifier and always turn the amplifier
off first before turning off the mixer.
C. Adjust Main/AUX out controls to the 2 o’clock position. Then turn amp up to
normal level while performing audio test.
D.Adjust input gain/trim control for each channel to get a meter reading within the
green area.
E.Adjust individual channel volume controls to the 2 o’clock position.
3. Fine Tuning (See page 16 for details).
A. In the event of excessive bass, press Low Cut filter switch(es) “on.”
B. If condenser mics are used, press phantom power switch “on” (turns phantom
power on for all inputs set to MIC position).
C. (CAM8PRO only) In the event of occasional excessive output level, press
Compressor/Limiter switch “on”.
Page 6 of 32
Panel Descriptions
CAM8 Front Panel
1. Main/Auxiliary Bus Selector (one per channel)
A 4-position switch which selects destination of channel input. Input can be
routed to: a) the main bus (M-up, A-down); b) the auxiliary bus (M-down,A-up
- shown at right); c) both the main and auxiliary bus (both up); or d) neither
bus (both down).
2. Channel Volume Control Knob (one per channel)
Controls the volume of the channel input to any and all outputs simultaneously.
3. Low Cut Switch
Helps eliminate low frequency noise (150 Hz 12dB/octave).
4. Main Output Volume Control Knob
Controls the output signal volume of the main bus.
5.Auxiliary Output Volume Control Knob
Controls the output signal volume of the auxiliary bus output and to the headphones (headphones on CAM8PRO only).
6. Power Indicator LED
LED displays mixer’s powered state. Lit when power is on. Not lit when power is off.
7. Power Switch Button
Push button to turn unit on (“in” position); push again to turn unit off (“out” position).
Page 7 of 32
2
+
-
M.A
BUS
1
+
-
M.A
Low
1
Cut
BUS
3 6
+
-
M.A
Low
2
Cut BUS
4 5
CAM8
+
-
M.A
Low
3
BUS
Cut
+
-
M.A
Low
4
BUSCut
+
-
M.A
Low
5
BUS
Cut
+
-
M.A
Low
6
Cut
BUS
+
-
M.A
Low
7
Cut
Low
BUS
Cut
AUXMAIN8
Power
7
+
M A
Bus
CAM8PRO Front Panel
1. Main/Auxiliary Bus Selector (one per channel)
A 4-position switch which selects destination of channel input. Input can be
routed to: a) the main bus (M-up,A-down); b) the auxiliary bus (M-down,A-upshown at right); c) both the main and auxiliary buses (both up); or d) neither bus
(both down).
2. Channel Volume Control Knob (one per channel)
Controls the volume of the channel input to any and all outputs simultaneously.
3. Low Cut Switch
Helps eliminate low frequency noise (150 Hz 12 dB/octave).
4. Main Output Compressor/Limiter Switch and LED
Note: Works only on main bus. Reduces distortion of the main output (due to clipping) by
controlling its dynamic range. When the LED (red) is lit, the Compressor/Limiter is on. The
brighter the LED, the more the signal is being compressed.
5. Main Output Volume Control Knob
Controls the output signal volume of the main bus.
6. LED Bar Graph Output Meter
Displays output signal level in decibels, ranging from -18 (green) to +12 (red) VU.
0 VU = +4 dBm.This meter can be set to indicate the signal level of either the main or aux-
iliary bus and to indicate either the average or peak signal. See page 19 for details.
7.Threshold Control
Screw-pot adjustment sets the signal level (-40 to +20 VU; factory setting is 0 VU) at which
the Compressor/Limiter becomes active.
8. Ratio Control
Screw-pot adjustment sets the amount of compression (0-100%; factory setting is 100%) of
the signal above the threshold.
9.Auxiliary Output Volume Control Knob
Controls the output signal volume of the auxiliary bus output and to the headphones (headphones on CAM8PRO only). (There is no connection between this bus and the
Compressor/Limiter.)
10. Headphone Jack
A 1/4 inch-diameter TRS mono-only jack for the connection of headphones. (Only monitors
AUX bus.)
11. Power Indicator LED
LED displays mixer’s powered state. Lit when power is on. Not lit when power is off.
12. Power Switch Button
Push button to turn unit on (“in” position); push again to turn unit off (“out” position).
2
Page 8 of 32
5 7 8 9
+
-
M.A
BUS
1
+
-
M.A
Low
1
Cut
BUS
3 4
+
-
M.A
Low
2
Cut BUS
+
-
Low
3
Cut
AUX
CAM8PRO
Headphone
10 11
Power
12
Ratio
Threshold
0 100
+20
MAIN
-40
-12-18 -6 -3
0 +3 +12+6
+
-
M.A
BUS
M.A
Low
4
BUSCut
+
-
M.A
Low
5
BUS
Cut
+
-
M.A
Low
6
Cut
BUS
+
-
M.A
Low
7
BUS
Cut
On
Off
Low
8
Limit
Cut
6
+
M A
Bus
CAM8/CAM8PRO Rear Panel
1. Ground Connection on Rear Panel
Access to ground.
2.AC Power Jack
Mixer power supply input. Accepts a 4-pin DIN connection from a 18V CT 1.5 Amp trans-
former (uses approximately 500 mA).
3. Phantom Power Switch
When activated, supplies 30V DC power to all inputs set to mic level.
4.Auxiliary Bus Output
Balanced, line-level, connection to auxiliary output bus.
5. Main Output Microphone/Line Switch
Selects main output to be either MIC (-50 dBµ) or line (0 dBµ) level.
6. Main Bus Output
Balanced connection to main output bus.
7.Auxiliary Input
Balanced, buffered, uncontrolled, line-level terminals for additional (ninth) input connection
directly to the summing buses selected by internal jumpers. The factory default is both
jumpers installed. For details, see page 19.
8. Input Gain/Trim Control Screw
Adjusts gain of input stage, over a range of 40 dB.
9. Input Pad Microphone/Line Switch
Selects either MIC (-50 dBµ) or line (0 dBµ) level for corresponding input connection.
10. Input
Balanced input connection (pluggable terminal strip).
1
Page 9 of 32
Ground
18VCT
AC
Power
-50dB
6
MAIN
0dB
4
AUX OUT AUX IN
On
Off
+-+-+-
Phantom
+-G
7 8
Trim
Line
--G--+++
+++++----G
Mic
Trim
8
7
Line
++++----
G++++----G
Mic
Trim
Line
Mic
Trim
6
5
Line
Mic
Line
++++----
G++++----G
Mic
TrimTrim
Line
Mic
Trim
34
Line
++++---
-G++++----G
Mic
Trim
12
Line
++++---
-G++++G----
Mic
2
3
5
9 10
Helpful Hints
Electrical equipment operates best in a clean, dry, well-ventilated environment free of vibration and electromagnetic fields. The following are some guidelines to achieve optimal performance.
Avoid placing the mixer and cables near heat sources. Be particularly aware of other audio
equipment, such as amplifiers, which can produce a great deal of heat when operating.
To minimize hum in the system, avoid placing the mixer and cables near radio frequency
devices and other electromagnetic field sources such as:
• Fluorescent lights
• Electrical motors
• SCR dimmers
• AC power lines, etc.
Note: Always use 2-conductor shielded cable to reduce EMI or RF interference to the
Line/MIC inputs.
Keep the mixer and other equipment clean and free of dust by wiping occasionally with a soft,
damp cloth.
Protect the mixer from electrical damage by disconnecting it from the power source whenever it will be unused for a week or longer.
The Bogen mixer is easy to install and adjust. The only tools needed are:
1. Slotted screwdriver
2. Phillips-head screwdriver
Page 10 of 32
Installation
Note: Take the mixer out of the box and inspect for shipping damage. If there is obvious
physical damage to the outside of the mixer, contact the supplier of the mixer before you
begin installation.
Rack Mounting:To mount CAM8 and CAM8PRO to a 19” rack, lift the unit up to the front of
the rack and secure it to the front of the rack with the necessary screws (not included with
this unit).
A.Turn all mixer Volume Control Knobs [Channel(s) (1), Main (2), and Auxiliary (3)] to zero.
Turn amplifier(s) volume controls to the 7 o’clock position.
B. Connect Inputs.
Connect lead into desired pluggable terminal strip (6) on rear panel.
Press Input Pad Microphone/Line Switch (5) to appropriate position:“in” for line input
or “out” for MIC input. Note that the input from some mics is actually close to line level
(-20 dB) and for such mics the switch should be at “Line.” Set switch for all unused channels
at Line level.The Auxiliary Input (4) is Line level only.
Page 11 of 32
1
+
-
M.A
BUS
+
-
M.A
Low
1
Cut
BUS
2 3
Threshold
-40
MAIN
-12-18 -6 -3
Limit
AUX
CAM8PRO
Headphone
Power
Ratio
0 100
+20
0 +3 +12+6
C. Connect Output: Make a connection between Main Bus Output Terminals (3) and an
input jack of an amplifier. Press Main Output Microphone/Line Switch (2) to appropriate position:“in” for line-level output (0 dBµ) or “out” for mic-level (-50 dBµ) output.
If desired, also connect Auxiliary Bus Output Terminals (1) to a second destination
device. The auxiliary output is line-level only.
D. Connect mixer power supply to an AC power outlet and to the AC Power Jack (4)
(located on far left side of rear panel).
E. Power up mixer:
Press Power Switch (8) to “in” position. [Power Indicator LED (7) will be lit if mixer is
powered.] Set Main Output Volume Control Knob (5) to 2 o’clock. If auxiliary output
is desired, also set Auxiliary Output Volume Control Knob (6) to 2 o’clock.
Power up amplifier.
Note: Mixer will produce signal transients on power up and power down.Always turn the
mixer on first before turning on the amplifier and always turn the amplifier off first before
turning off the mixer.
Page 12 of 32
1
On
Off
Phantom
AUX OUT
+-+-+-
+-G
-50dB
0dB
3
MAIN
++++----G
2
Operation
The primary goal when establishing the gain settings of the mixers is to have each channel
operating at the maximum gain without clipping, while leaving adequate headroom on the volume control knob.
The channel Input Gain/Trim Control (1) on the rear panel of the mixers directly controls
the microphone pre-amplifier gain available at each channel.
The Volume Control (2) on the front panel controls how much of the gain is routed to the
main output stage.The front panel controls should optimally operate between the 9 and
2 o’clock position when gain structure is correct (see example on page 14).
The Main Output Volume Control Knob (3) on the front panel controls the mixer’s final
amplifier stage to the master output.This control should optimally operate between the 9 and
2 o’clock positions when gain structure is correct.
With all channels operating, the main output meter should show a signal output range
between 0 and +6 VU. Adjust the main output control accordingly. If the output occasionally
peaks in the range of +6 and +12 VU, activate the Compressor/Limiter (see page 17).
The amplifier for the loudspeakers should be the final control for establishing volume levels.
Note: The channel Input Gain/Trim Controls are factory preset to produce a 0 dBµ sig-
nal level at the master output when the front panel volume controls are set at the 2 o’clock
position.This setting is optimal with most input devices.
Page 13 of 32
1
Trim
6
Line
Mic
++++----G
2
+
-
M.A
BUS
+
-
M.A
Low
1
Cut
BUS
3
Ratio
Threshold
0 100
+20
-40
-12-18 -6 -3
Limit
MAIN
0 +3 +12+6
Troubleshooting Gain Structure
If the procedure followed to this point does not give satisfactory results, follow the
appropriate adjustment sequence below:
If channel clipping occurs
If the signal is clipping or producing audible distortion, the gain is too high. Reduce the Input
Gain/Trim Control (rear panel) by turning it counterclockwise until clipping does not occur.
Also make sure that the new setting of the gain control offers a usable control range between
the 9 o’clock and 2 o’clock positions on the front panel volume control knob.
If channel volume is too low
If a channel must be set above the 2 o’clock position to provide adequate volume, the input
gain setting is too low.Turn the volume control knob to the 1 o’clock position and increase
the input gain by turning the input gain/trim control clockwise until clipping occurs, or VU
meter is over 0 VU.Then adjust the gain to a setting just below the clipping level.
If channel volume is too high
If a channel is not clipping but must be set below the 9 o’clock position to achieve the proper volume level,the input gain control setting is too high. Reduce the Input Gain/Trim Control
by turning it counterclockwise. Set the volume control knob to the 9 o’clock position and
continue to adjust the gain control until the desired volume level is achieved.
Page 14 of 32
Range for optimal volume control operation
settings (indicator positions).
Recommended Input Wiring Methods
These are the best ways to connect sources to the mixer.The mixer input is always balanced.
From the drawings below choose the wiring method for your input device (either balanced
or unbalanced).
Balanced Source to Balanced Input - Method 1 (Normal)
Shown below is the normal wiring method for a balanced source device. It has +6 dB gain and
excellent ground current and noise rejection.
Balanced Source to Balanced Input - Method 2
If the method above does not work in your application, use the wiring shown below. This
method can solve certain ground loop problems.It has +6 dB gain and good noise and ground
loop rejection.
Unbalanced Source to Balanced Input - Method 1
For an unbalanced source device, the drawing below shows the best wiring method. Because
of the design of the mixer, this wiring provides a slight (+6 dB) boost, and moderate noise and
ground loop rejection.
Unbalanced Source to Balanced Input - Method 2
For an unbalanced source device, the drawing below shows an alternative wiring method.
Because the grounding of the minus input is not to the mixer ground, this method does not
provide the +6 dB boost. Ground current and noise rejection is good.
Page 15 of 32
Balanced Source
Balanced Source
-
-
+
Gnd
-
+
Gnd
No connect
+
G
+
G
+
-
+
-
-
Gnd
Unbalanced Source
+
+
G
+
-
-
Gnd
Unbalanced Source
+
+
G
+
Fine Tuning
Low Cut Switch
To remove excessive bass from an individual channel, press the Low Cut Switch (1) for that
channel.
This feature helps eliminate low frequency noise (signals of 150 Hz and below, such as back-
ground rumble from ventilation systems, etc.) and is used primarily with mic-level input. It is
particularly effective when handheld mics are used.
Phantom Power
If a condenser microphone(s) is not independently powered, press Phantom Power Switch
(2) to the “on” position.
The phantom power switch will power condenser (capacitor) mics through the mic cable.
Depressing the button simultaneously applies phantom power to all channels set to mic-level.
Page 16 of 32
+
-
M.A
BUS
+
-
M.A
Low
1
Cut
BUS
1
Compressor/Limiter (CAM8PRO only)
The Compressor/Limiter (1) is a dynamic range controller that can be used to compen-
sate for signals that may sound unnatural or cause audible distortion.This is indicated by the
LED Bar Graph Output Meter (3) occasionally exceeding +12 VU (red).
Note: The Compressor/Limiter is only available on the CAM8PRO and only affects the main
channel.
A Compressor is used to slightly reduce the dynamic range of a signal.This effect is perceived
to quiet loud sounds and boost quiet sounds.A compressor smooths transients.
A Limiter is used to prevent a signal from exceeding a certain level. This function guards
against amplifier or recording level overloads.The Compressor/Limiter is activated by pressing the Main Output Compressor/Limiter Switch.
This dynamic controller allows for compression and limiting functions by controlling
threshold and ratio.
The Threshold Control (2) is a screw potentiometer that sets what signal level will acti-
vate the Compressor/Limiter. It has a range of -40 to +20 dB.
The Ratio Control (4) is a screw potentiometer that sets the compression ratio that will
be applied when the signal exceeds the threshold. It has a range from 0% to 100%. A
Compressor becomes a Limiter when the compression ratio is 10:1 or greater.
The factory setting for the threshold is 0 VU (+4 dB), but this is variable (from -40 dB to +20
dB) and can be changed by adjusting the Threshold Control. Likewise, the factory setting for
the compression ratio is 100% (at this maximum setting, the circuit performs the limiter function), but can be set to between 0 and 100% by adjusting the Ratio Control.
Note:The LED Bar Graph Output Meter can be used to view the effects of adjusting the
Compressor/Limiter controls. Turn off power amplifiers while performing these adjustments.
Warning:If the amplifier/speaker combination being used is such that the speaker(s)
can be overdriven to failure, always operate the mixer with the Output Limit Switch
in the “on” position and the ratio should be set at 100%.
Page 17 of 32
2
Threshold
0 100
+20
-40
-12-18 -6 -3
Limit
MAIN
0 +3 +12+6
4
Ratio
1
3
Special Features Activation
The CAM8-Series mixers have several built-in features which are easily activated by making
adjustments inside the mixer chassis. Changing the selection of all built-in features requires
only the correct placement of internal jumpers or varying the settings of an internal potentiometer.
Note:All the internal components — jumpers and potentiometers — to which adjustments
are needed for built-in features are highlighted within dashed areas in the drawing below.
Warning: Adjustments made to any other internal components may void the warranty.
Page 18 of 32
LEFT
REAR
FRONT
RIGHT
AUX IN
AUX IN
J17
J18
METER RESPONSE
J20 J21
AVG
MAIN
OUTPUT
VOLUME
KNOB
PEAK
OUTPUT
LIMITER
SWITCH
MAIN OUT AUX OUT POWER
MAIN BUS
AUX BUS
METER SOURCE
J23
AUX SOURCE
J1
J2
-
AUX
BUS
INT
EXT
AUX
PREGAIN
POT
RP23
AUX
OUTPUT
VOLUME
KNOB
MAIN
BUS
+
LED BAR GRAPH METER
J22
Power
Switch
Button
Jumper Options
Changing Jumper Settings
To change a jumper setting, remove the ten screws secured to the top of the mixer. After
removing the top of the mixer, locate the jumper to be changed by referring to the drawing
on page 18. Jumpers are included from the factory in positions: J2, J17, J18, J21, and J22.
Warning: Disconnect AC Power before opening case.
Bar Graph Options
The mixer’s meter can be configured to meter the output of either the main or auxiliary bus.
In addition, the bar graph can be configured to register either the peak or average level of the
audio signal.
J22-J23
The LED Bar Graph Output Meter can be set to register either the main or auxiliary bus
output audio signal. The choices are:
J22 installed:The Bar Graph meters the main bus output. This is the factory default.
J23 installed:The Bar Graph meters the auxiliary bus output.
Note: The meter will operate only when a jumper is in one of these two positions.
J20-J21
The LED Bar Graph Output Meter can be set to register either the peak or average level
of the output audio signal.The choices are:
J20 installed:The Bar Graph meter registers the peak level of the audio output.
J21 installed:The Bar Graph registers the average level of the audio output. This is the
factory default.
Note:The meter will operate only when a jumper is in one of these two positions.
Bus Routing Options
AUX In Jumpers: J17 and J18. These jumpers determine the destination of the Auxiliary
Input.The choices are:
J17 installed:Auxiliary Input is routed to Main Output.
J18 installed:Auxiliary Input is routed to Auxiliary Output.
J17 and J18 both installed:Auxiliary Input is routed to both Main and AUX outputs.This is the
factory default setting.
AUX Source Jumpers:J1 and J2. These jumpers determine which of two gain controls are
used to control the level of the AUX output.The choices are:
J1 installed:AUX output gain is controlled by the internal pot,“AUX Pregain Pot” RP23 (see
page 18 for location).The front panel AUX output volume knob continues to independently
control the gain of the headphone amplifier jack on the front panel.This setting is typically
used in a linking situation where the output from a mixer must remain fixed, since J1 makes
the output of that mixer tamper-proof (from the front panel).With J1 installed, the front panel
AUX volume knob controls only the headphone level.
J2 installed:AUX output gain is controlled by AUX volume knob on front panel.The 1/4-inch
Headphone amp is also controlled by the AUX volume knob, but not independently of the
AUX output.
Note: Never install jumpers in both positions J1 and J2. If both J1and J2 jumpers are installed,
then gain is defeated.
Page 19 of 32
Linking
CAM8-Series mixers can be linked in several ways.The two principal ways of linking the mixers are Simple and Complex Linking.
Simple Linking is the expansion to more than 8 inputs by connecting two 8-channel mixers via the auxiliary bus. Simple Linking is the “daisy-chaining” of multiple mixers to expand
the number of inputs routed to a single output. Inputs can be multiplied in increments of 8 by
adding mixers to the chain.
The number of mixers that can be daisy-chained is limited only by the accumulation of noise.
Typically, 6 mixers with 48 inputs “on” can be used without excessive degradation.This gives
you the equivalent of 48 inputs (MIC inputs). Each doubling of inputs reduces the system’s
noise floor by 6 dB.An example of Simple Linking is shown on page 21.
Complex Linking allows the use of multiple 8X2 channel mixers as a single 2-output mixer.
For example, two mixers can be linked as a 16X2 channel mixer stack in which there are two
separate output mixes with full control over distribution of the inputs to the two outputs.
Among other applications this feature can be used to implement the so-called “mix minus”
technique, in which no microphone drives the output nearest itself.An example of Complex
Linking is shown on page 22.
There are other techniques for linking, not shown here. If you have questions regarding a
linked application not shown, please contact Bogen’s Applications Engineering department.
Page 20 of 32
Simple Linking
Simple linking or “daisy-chaining” allows the expansion of mixer inputs in multiples of 8 inputs
by chaining together multiple mixers with auxiliary buses.To preserve certain mixer features,
this must be done in the way shown below. Follow these steps (see page 18 for jumper loca-
tions):
1. For each mixer, remove the jumper from J2 and place it on J1.This causes the Auxiliary
Out level to be set by an internal pot, fixing the linked gain structure.The external pot only
controls the headphone out level.
2. In the last mixer in the chain, remove the jumper from J18. Leave the jumper in place on
J17.This routes the AUX In to the Main output, preserving the Compressor/Limiter feature.
3.All other mixers in the chain should have jumper J18 in place, and J17 removed.
4. Connect each mixer’s AUX Out terminals with the AUX In terminals of the next mixer in
the chain.
5.Take the summed daisy-chain output from the Main Out terminals of the last mixer in the
daisy-chain.This must be the mixer with J17 in place (from step 2).
6. All mixers except the last mixer in the chain (#1 in the drawing below) must have all its
front panel M-A switches in the A position, to route its inputs to the auxiliary bus. The posi-
tion of jumpers J17 and J18 in the first mixer (#4 in the drawing below) do not matter, and
can be left undisturbed.
You should now have a daisy-chain configured as shown in the drawing below. Note that the
position of J17 and J18 are shown within the drawing of each mixer in the chain (except mixer
#4 in which the jumper position is immaterial).
Page 21 of 32
Aux Out
Mixer 1
Main Out
J17
Aux In
Aux Out
Mixer 2
J18
Main Out
Aux In
Aux Out
Mixer 3
J18
Main Out
Aux In
Aux Out
Mixer 4
Main Out
Aux In
Complex Linking
Complex Linking allows multiple mixers to produce two separate mixes from the same set
of inputs.The most common complex linking application is shown below.This method can also
be used to implement a “mix minus” application.
This method (CAM8PRO only) creates two separate mixes. Both destinations are routed
through the Compressor/Limiter, since both destinations are driven by Main outputs.
Destination 1 receives inputs from Mixer 1 with Main/Auxiliary bus selector set to Main, and
inputs from Mixer 2 with Main/Auxiliary bus selector set to AUX. Destination 2 receives
inputs from Mixer 1with Main/AUX set to AUX, and inputs from Mixer 2 with Main/AUX set
to Main.
To create this complex mix, take the following steps:
1. Following the directions on page 19, set jumpers as shown in the drawing below:
J17 alone in both mixers.
2. For both mixers, remove jumper from position J2 and place it in position J1.This
gives internal control of both auxiliary buses.
3. Connect the two mixers as shown in the drawing below.
Page 22 of 32
Destination 1 receives inputs from mixer 2 with the
M-A switch set to auxiliary, and from mixer 1 with the
M-A switch set to main.
Destination 2 receives inputs from mixer 2 with
the M-A switch set to main, and from mixer 1 with
the M-A switch set to auxiliary.
Mixer 1
J17
Aux Out
1
Main Out
Aux In
Mixer 2
J17
Aux Out
Main Out
Aux In
2
AC Power Connection
This mixer is powered by an 18 Volt, 1.5 Amp center-tapped transformer (supplied). If another AC supply is used, it should be of equal voltage and have at least a 21Volt-Amp rating.The
details of the AC Power Jack on the rear panel are as shown in the following figure.
Technical Support
Our Applications Engineering Department is available to help you troubleshoot problems
with your Bogen equipment. Engineers are available from 8:30 AM to 6:00 PM, Eastern
Standard Time. Phone 1-800-999-2809.
Page 23 of 32
Center
No connect
AC
AC
Troubleshooting Tips
NO POWER
Check the connections between the mixer and the power supply and the external AC power
supply. Examine the 4-pin connector as shown on page 23.
Check the wall outlet.
NO SOUND
• Make sure the MIC/Line switch is in the proper position. (This is the most likely
cause.)
• Make sure both the master and channel input controls are turned up.
• Check that the source signal cable(s) is properly connected and undamaged.
• Adjust Input Gain/Trim Control potentiometer(s) to increase gain.
• If there is still no sound, try changing input source(s) to different channel(s).
DISTORTED SOUND
• Turn down the master volume control. If distortion persists, input channel(s) gain
is the likely cause.
• Check position of all line/MIC switches.
• Determine the distorting input channel(s) by checking them one at a time.
• Decrease gain of input channel(s) causing distortion by turning the screw on the
rear panel.
EXCESSIVE HISS or HUM
Hiss: Make sure the volume control knobs for all the unused channels are turned all the way
off (i.e., at the 7 o’clock position).
• Make sure that all unused input channels have the MIC/Line switch in the Line
position.
• Make sure the MIC/Line switch is in the correct position for both the inputs and
the main output.
Hum: MIC lines can easily cause hum. Make sure to locate them away from vibration and
magnetic field sources (motors, power supplies and lines, and data lines).
Check MIC lines, especially the shield, for damage.
Another common source of hum is a ground loop, which can result from connecting two or
more powered devices together.
Turn both the Main and Auxiliary volume controls down. If the hum is still present, the ground
loop or other cause is not in the mixer, but in the devices after it in the audio path or in the
connection between the mixer and following equipment. (If the hum disappears, then the
cause is either in the mixer or in one of the inputs to the mixer. Turn each of the volume
controls [both the individual input channels and the two buses] down independently, to determine which one is the source of the hum.)
Check for unbalanced connections; use balanced connections, if possible. For all unbalanced
connections, try disconnecting the signal line ground to eliminate multiple ground paths.
Page 24 of 32
Glossary
Auxiliary Input - Accepts only a balanced, line-level input (unlike the 8 channels); the auxil-
iary input has no volume control.
Compression Ratio - The ratio of the output level above the threshold level to the input
level above the threshold.
Compression Threshold - The volume level, in dB, which is set as the optimum device
operating level, and above which the Compressor/Limiter begins to operate.
Compressor - A special type of limiting device, which controls the total volume level of a
signal by compressing the part of the signal which exceeds a predetermined threshold. The
threshold can be varied.
Gain/Trim Control - Gain is the ratio between the input and output signal levels.Trim is
the adjustment of the gain of the input stage to offset the differences between input signal
levels.
Ground Loop - A condition which can occur when several ground pathways exist between
two or more devices and which can cause hum in the audio signal.
Jumper - A short length of conductor used to connect pins electrically.
Limiter - A device that severely (at rates greater than 10:1) restricts the upper dynamic
range of a signal, by regulating the rate of increase of an input signal’s amplitude so that it will
not exceed a predetermined threshold.
Line/Microphone Level - The two signal level ranges at which the mixer accepts input. MIC
level is usually -50 dBµ and Line level is usually +4 dB.
Low Cut Switch - Removes the lower-frequency (<150 Hz) components, which cause rum-
ble, from a signal.
Phantom Power - A method of powering condenser microphones by sending DC current
over the same MIC cable that carries the audio signal. Called “Phantom” as there is no visible power cord and the voltage is not perceptible in the audio signal.
Pot - Potentiometer.
RCA Connector - An unbalanced line level connection, also known as “phono connector.”
Summing Junction - The point in the CAM8-Series circuitry where the audio signals are
mixed.
Page 25 of 32
Technical Information
SPECIFICATIONS
Signal-to-Noise Ref +26 dBV @ 54 dB sys gain = 90 dB
MIC Pre-amp Equivalent Input Noise -129 dB @ 150 ohm, 20 Hz to 20 kHz
Maximum Voltage Gain 96 dB
Frequency Response ± 1 dB from 20 Hz to 20 kHz
+0, -3 dB from 10 Hz to 30 kHz
Crosstalk (adjacent channels) better than -90 dB
Phantom Power +30V DC
INPUTS 1-8
Input Impedance 3.5k ohm Mic
15k ohm Line
Nominal Source Impedance 150 ohm
Line Pad -50 dB
Input Gain/Trim Range 40 dB
Nominal Level (input trim pot mid-range) -50 dBµ line pad off
0 dBµ line pad on
Minimum Level (input trim pot max gain) -70 dBµ line pad off
-20 dBµ line pad on
Maximum Level (input trim pot min gain
plus +20 dB headroom) -30 dBµ line pad off
+20 dBµ line pad on
AUXILIARY INPUT
Input Impedance 20k ohm balanced
Nominal Input Level 0 dBm
OUTPUTS
Output Impedance 220 ohm unbalanced, 440 ohm balanced
Nominal Load Impedance >600 ohm
Nominal Level +4 dBµ RMS
Maximum Level +26 dBµ RMS Balanced
Main Output MIC Pad -50 dB
Page 26 of 32
Auxiliary Circuits
Bar Graph -18, -12, -6, -3, 0, +3, +6, +12 VU
(0 VU = +4 dB)
Average or Peak reading
Peak reading per DIN spec. 45406
(1.7 ms attack, 650 ms decay)
Compressor/Limiter Adjustment Range +20 dB to -40 dB
Compressor/Limiter Ratio Adjustment Range 0 to 100%
Low Cut Filter 12 dB/octave at 150 Hz
Power Requirements 18V AC center-tapped, 21V AC/120V AC, 60 Hz
±18 - 24V DC, 450 mA
Dimensions 19" W x 1-3/4" H x 6" D
Shipping Weights (CAM8) 10 lb.
(CAM8PRO) 10 lb.
Page 27 of 32
Block Diagram
Page 28 of 32
Aux output
Headphone
+4 dB
J21
Ave
J20
Peak
Aux
J22
Meter
Bar Graph
Line/mic
J23
Main
6 dB
PAD
Main
Line/mic
output
+4/-50 dB
20 dB
20 dB
20 dB
20 dB
Post
Pre
J2
J1
RP 23
Pre-gain
volume
Sum
A
M
Aux
A
M
INPUT 1
20 dB150Hz
Ratio
Threshold
INPUT 2
Limit in/out
Limiter
Control
Sum
Main volume
Main
J17
Aux
J18
Bus
AREAS IN DASHED LINES
DO NOT APPLY TO THE CAM8
Aux Line Input
(Link Input)
150Hz
+10 to +50 dB
Mic/line
Hi Pass
PAD
Mic/line
input
In/out
-70/-50 dB
-10/+10 dB
+10 to +50 dB
PAD
Mic/line
Hi Pass
Mic/line
input
In/out
-10/+10 dB
-70/-50 dB
Page 29 of 32
Warranty
The CAM8 and CAM8PRO are warranted to be free from defects in material or workmanship for two (2) years from the date
of sale to the original purchaser.Any part of the product covered by this warranty that, with normal installation and use, becomes
defective will be repaired or replaced by Bogen, at our option, provided the product is shipped insured and prepaid to: Bogen
Factory Service Department, 50 Spring Street, Ramsey, NJ 07446, USA.The product will be returned to you freight prepaid.This
warranty does not extend to any of our products that have been subjected to abuse, misuse, improper storage, neglect, accident,
improper installation or have been modified or repaired or altered in any manner whatsoever, or where the serial number or
date code has been removed or defaced.
THE FOREGOING LIMITED WARRANTY IS BOGEN'S SOLE AND EXCLUSIVE WARRANTY AND THE PURCHASER'S SOLE AND EXCLUSIVE REMEDY. BOGEN MAKES NO OTHER WARRANTIES OF ANY KIND,
EITHER EXPRESS OR IMPLIED, AND ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED AND EXCLUDED TO THE MAXIMUM EXTENT
ALLOWABLE BY LAW. Bogen's liability arising out of the manufacture, sale or supplying of products or their use or dispo-
sition, whether based upon warranty, contract, tort or otherwise, shall be limited to the price of the product. In no event shall
Bogen be liable for special, incidental or consequential damages (including, but not limited to, loss of profits, loss of data or loss
of use damages) arising out of the manufacture, sale or supplying of products, even if Bogen has been advised of the possibility of
such damages or losses. Some states do not allow the exclusion or limitation of incidental or consequential damages,so the above
limitation or exclusion may not apply to you.This warranty gives you specific legal rights,and you may also have other rights which
vary from state to state.
Products that are out of warranty will also be repaired by the Bogen Factory Service Department — same address as above or
call 201-934-8500. The parts and labor involved in these repairs are warranted for 90 days when repaired by the Bogen Factory
Service Department. All shipping charges in addition to parts and labor charges will be at the owner's expense.All returns require
a Return Authorization number.
8/2004
Page 30 of 32
Page 31 of 32
50 Spring Street, Ramsey, NJ 07446
Tel. 201-934-8500, Fax: 201-934-9832
www.bogen.com
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