Bogen Musical Instrument CAM8 User Manual

CAM8-Series  
Models CAM8, CAM8PRO  
Installation and Use Manual  
© 2000 Bogen Communications, Inc.  
All rights reserved.  
54-2034-01C 0508  
 
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  
CAM8-Series  
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 sim-  
ple-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.  
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.  
FineTuning (See page 16 for details).  
3.  
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  
2
4
5
CAM8  
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
M.A  
BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low  
Cut  
Power  
1
2
3
4
5
6
7
8
MAIN  
AUX  
1
3
6
7
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).  
+
-
M A  
Bus  
2. ChannelVolume 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 OutputVolume Control Knob  
Controls the output signal volume of the main bus.  
5.Auxiliary OutputVolume Control Knob  
Controls the output signal volume of the auxiliary bus output and to the headphones (head-  
phones 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
5
7
8
9
CAM8PRO  
Threshold Ratio  
-40  
+20  
0
100  
On  
Off  
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
-18 -12 -6 -3  
0
+3 +6 +12  
M.A  
BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low M.A  
Cut BUS  
Low  
Cut  
Limit  
Headphone Power  
1
2
3
4
5
6
7
8
MAIN  
AUX  
1
3
4
6
10 11 12  
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-up-  
shown at right); c) both the main and auxiliary buses (both up); or d) neither bus  
(both down).  
-
M A  
Bus  
2. ChannelVolume 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 OutputVolume 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.  
0VU = +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 OutputVolume Control Knob  
Controls the output signal volume of the auxiliary bus output and to the headphones (head-  
phones 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).  
Page 8 of 32  
 
-
+
G
-
+
G
                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                 
                                                                                                                                                                                                                                                 
G
-
+
G
-
+
G
-
+
G
-
+
G
-
+
G
-
+
G
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
-
+
-
+
G
-
+
1
4
6
7
8
18VCT  
AC  
Trim  
Trim  
Trim  
Trim  
Trim  
Trim  
Trim  
Trim  
Ground  
AUX OUT  
MAIN  
AUX IN  
8
7
6
5
4
3
2
1
On  
Off  
Line  
Mic  
Line  
Mic  
Line  
Mic  
Line  
Mic  
Line  
Mic  
Line  
Mic  
Line  
Mic  
Line  
Mic  
-50dB  
0dB  
Power  
Phantom G  
3
5
9
10  
2
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).  
Page 9 of 32  
 
Helpful Hints  
Electrical equipment operates best in a clean, dry, well-ventilated environment free of vibra-  
tion and electromagnetic fields. The following are some guidelines to achieve optimal per-  
formance.  
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 when-  
ever 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.  
1
2
3
CAM8PRO  
Threshold Ratio  
-40  
+20  
0
100  
+
-
+
-
-18 -12 -6 -3  
0
+3 +6 +12  
Limit  
M.A  
BUS  
Low M.A  
Cut BUS  
Headphone Power  
MAIN  
AUX  
1
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  
 
C. Connect Output: Make a connection between Main Bus OutputTerminals (3) and an  
input jack of an amplifier. Press Main Output Microphone/Line Switch (2) to appropri-  
ate position:in” for line-level output (0 dBµ) or “out” for mic-level (-50 dBµ) output.  
1
3
AUX OUT  
MAIN  
On  
Off  
-50dB  
0dB  
-
+
-
+
G
Phantom G  
2
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 OutputVolume 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  
 
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 vol-  
ume 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.  
1
Trim  
6
Line  
Mic  
+
G
-
TheVolume 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).  
2
+
-
+
-
M.A  
BUS  
Low M.A  
Cut BUS  
1
The Main OutputVolume 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 +6VU. Adjust the main output control accordingly. If the output occasionally  
peaks in the range of +6 and +12VU, activate the Compressor/Limiter (see page 17).  
3
Threshold Ratio  
-40  
+20  
0
100  
-18 -12 -6 -3  
0
+3 +6 +12  
Limit  
MAIN  
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  
 
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 0VU.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 prop-  
er 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.  
Range for optimal volume control operation  
settings (indicator positions).  
Page 14 of 32  
 
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.  
-
-
+
-
+
+
Gnd  
Balanced Source  
G
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.  
-
-
-
+
+
+
Gnd  
G
Balanced Source  
No connect  
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.  
-
-
+
+
+
Gnd  
G
Unbalanced Source  
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.  
-
-
+
+
+
Gnd  
Unbalanced Source  
G
Page 15 of 32  
 
FineTuning  
Low Cut Switch  
To remove excessive bass from an individual channel, press the Low Cut Switch (1) for that  
channel.  
+
-
+
-
M.A  
BUS  
Low M.A  
Cut BUS  
1
1
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  
 
Compressor/Limiter (CAM8PRO only)  
2
4
Threshold Ratio  
-40  
+20  
0
100  
-18 -12 -6 -3  
0
+3 +6 +12  
Limit  
MAIN  
3
1
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 +12VU (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 press-  
ing 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 0VU (+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 func-  
tion), 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  
 
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 poten-  
tiometer.  
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.  
AUX IN  
MAIN OUT  
AUX OUT  
POWER  
AUX IN  
REAR  
MAIN BUS  
AUX BUS  
J17  
J18  
RIGHT  
LEFT  
METER SOURCE  
FRONT  
AUX  
BUS  
MAIN  
BUS  
J23  
J22  
AUX SOURCE  
J1  
INT  
METER RESPONSE  
J2  
EXT  
PEAK  
AVG  
J20 J21  
AUX  
PREGAIN  
POT  
-
+
RP23  
Power  
Switch  
Button  
LED BAR GRAPH METER  
OUTPUT  
LIMITER  
SWITCH  
MAIN  
OUTPUT  
VOLUME  
KNOB  
AUX  
OUTPUT  
VOLUME  
KNOB  
Page 18 of 32  
 
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 andAUX 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 J1 and 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 mix-  
ers are Simple and Complex Linking.  
Simple Linking is the expansion to more than 8 inputs by connecting two 8-channel mix-  
ers 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 ordaisy-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).  
Mixer 2  
Mixer 3  
Mixer 4  
Mixer 1  
J18  
J18  
J17  
Main Out  
Main Out  
Main Out  
Main Out  
Aux Out  
Aux In  
Aux Out  
Aux In  
Aux Out  
Aux In  
Aux Out  
Aux In  
Page 21 of 32  
 
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 1 with Main/AUX set toAUX, 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.  
Mixer 2  
Mixer 1  
J17  
J17  
Main Out  
Main Out  
Aux Out  
Aux In  
Aux Out  
Aux In  
1
2
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.  
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.  
Page 22 of 32  
 
AC Power Connection  
This mixer is powered by an 18Volt, 1.5 Amp center-tapped transformer (supplied). If anoth-  
er 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.  
Center  
No connect  
AC  
AC  
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  
 
TroubleshootingTips  
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 andAuxiliary 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 deter-  
mine 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 visi-  
ble 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  
-129 dB @ 150 ohm, 20 Hz to 20 kHz  
96 dB  
MIC Pre-amp Equivalent Input Noise  
MaximumVoltage Gain  
Frequency Response  
± 1 dB from 20 Hz to 20 kHz  
+0, -3 dB from 10 Hz to 30 kHz  
better than -90 dB  
Crosstalk (adjacent channels)  
Phantom Power  
+30V DC  
INPUTS 1-8  
Input Impedance  
3.5k ohm Mic  
15k ohm Line  
150 ohm  
Nominal Source Impedance  
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  
-70 dBµ line pad off  
-20 dBµ line pad on  
Minimum Level (input trim pot max gain)  
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  
Nominal Input Level  
20k ohm balanced  
0 dBm  
OUTPUTS  
Output Impedance  
Nominal Load Impedance  
Nominal Level  
220 ohm unbalanced, 440 ohm balanced  
>600 ohm  
+4 dBµ RMS  
Maximum Level  
Main Output MIC Pad  
+26 dBµ RMS Balanced  
-50 dB  
Page 26 of 32  
 
Auxiliary Circuits  
Bar Graph  
-18, -12, -6, -3, 0, +3, +6, +12VU  
(0VU = +4 dB)  
Average or Peak reading  
Peak reading per DIN spec. 45406  
(1.7 ms attack, 650 ms decay)  
Compressor/Limiter Adjustment Range  
Compressor/Limiter Ratio Adjustment Range  
Low Cut Filter  
+20 dB to -40 dB  
0 to 100%  
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)  
(CAM8PRO)  
10 lb.  
10 lb.  
Page 27 of 32  
 
Block Diagram  
Page 28 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 LIMITEDWARRANTY IS BOGEN'S SOLE AND EXCLUSIVEWARRANTY ANDTHE PUR-  
CHASER'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 EXCLUDEDTOTHE 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 29 of 32  
 
Page 30 of 32  
 
Page 31 of 32  
 
50 Spring Street, Ramsey, NJ 07446  
Tel. 201-934-8500, Fax: 201-934-9832  
 

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