American Audio Stereo Amplifier V4000 plus User Manual

Professional Power Amplifier  
MONO STEREO BRIDGE  
LIMITER  
LIMITER  
POWER  
ON  
OVER HEAT  
PROTECT  
CLIP  
ON  
ON  
-5dB  
-10dB  
OFF  
-15dB  
SIGNAL  
0
0
10  
10  
PROFESSIONAL POWER AMPLIFIER  
V4000
plus  
AMERICAN AUDIO
®  
4295 Charter Street  
Los Angeles Ca. 90058  
User Instructions  
Revised 02/02  
 
CAUTION  
Do not open -  
risk of electric shock  
POUR ASSURER LA FIABILETE ET  
OBTENIT UNE PERFORMANCE OPTIMALE,  
NESOUMETTE JAMAIS LAMPLIFICATEUR  
A UNE CHARGE D’IMPEDANCE TOTALE  
INFERIEURE A 2 OHMS, NI AVEC UN H.P. NI  
EN COMBINAISON DES H.P.  
FOR OPTIMUM PERFORMANCE AND  
RELIABILITY DO NOT PRESENT THE  
AMPLIFIER WITH A SPEAKER LOAD  
OF LESS THAN 2 OHMS OR ANY  
COMBIN
A
T
ION OF SPEAKERS TH
A
T  
TOGETHER ARE LESS THAN 2 OHMS!  
CAUTION: TO REDUCE THE RISK OF ELECTRIC  
SHOCK, DO NOT REMOVE THE COVER.  
THERE ARE NO USER SERVICEABLE PARTS  
INSIDE. REFER ALL SERVICE TO YOUR  
AUTHORIZED AMERICAN AUDIO® DEALER.  
The lightning flash with an arrow triangular  
symbol is intended to alert the user to the  
presence of non insulated “dangerous volt-  
age” within the products enclosure, and  
may be of sufficient magnitude to consti-  
tute a risk of electric shock.  
AVEC UN H.P., IL FAUT UNE CHARGE  
D’IMPEDANCE MINIMUM DE 2 OHMS.  
USING ONE SPEAKER, IT MUST BE  
R
A
T
ED
A
T 4
O
R MORE OHMS.  
USING TWO SPEAKERS, THEY MUST  
R
A
T
ED EACH
 
A
T 4
O
R MORE OHMS.  
AVEC DEUX H.P., FAUT POUR CHAOUN UNE  
CHARGE D’IMPEDANCE MINIMUM DE 4  
OHMS.  
The exclamation point triangular symbol is  
intended to alert the user to the presence  
of important operating and maintenance  
(servicing) instructions in the user manual  
accompanying the amplifier.  
USING THREE SPEAKERS, THEY  
MUST BE RATED EACH AT 8 OR  
MORE OHMS.  
AVEC TROIS H.P., FAUT POUR CHAOUN UNE  
CHURGE D’IMPEDANCE MINIMUM DE 8  
OHMS.  
CONTENTS:  
SafetyPrecautions........................................................................................................................................................................................4  
Introduction...............................................................................................................................................................................................4  
FrontPanel....................................................................................................................................................................................................5  
Rear Panels..................................................................................................................................................................................................6  
Inputs...........................................................................................................................................................................................................7  
Outputs............................................................................................................................................................................................................7  
Operating Modes.........................................................................................................................................................................................9  
Protection Circuitry  
Limite
r
.
................................................................................................................................................................................................10  
ShortCircuitProtection.....................................................................................................................................................................10  
Therma
l
P
rotection...........................................................................................................................................................................11  
Important Features.....................................................................................................................................................................................11  
Speakon Output Connector Assembly.......................................................................................................................................................12  
Specifications...............................................................................................................................................................................................15  
 
Important Precautions  
Introduction  
To reduce the risk of electrical shock or fire, do not expose this  
unit rain or moisture  
Introduction: Congratulations and thank you for purchasing  
the American Audio
®
V4000
plus™ amplifier. This amplifier is a  
representation of American Audio’s continuing commitment to  
produce the best and highest quality products all at an affordable  
price. Please read and understand this manual completely before  
attempting to operate your new amplifier. This booklet contains  
important information concerning the proper and safe operation  
of your new amplifier.  
• Do not spill water or other liquids into or on to your unit  
• Do not attempt to operate this unit if the power cord has been  
frayed or broken  
• Do not attempt to remove or break off the ground prong from  
the electrical cord. This prong is used to reduce the risk of elec-  
trical shock and fire in case of an internal short  
• Disconnect main power before making any type of connection  
• Do not remove the cover under any conditions. There are no  
user serviceable parts inside  
Unpacking: Every V4000plus™ amplifier has been thoroughly  
tested and has been shipped in perfect operating condition.  
Carefully check the shipping carton for damage that may have  
occurred during shipping. If the carton appears to be damaged,  
carefully inspect your unit for any damage and be sure all acces-  
sories necessary to operate the unit has arrived intact. In the  
event damage has been found or parts are missing, please con-  
tact our toll free customer support number for further instructions.  
Please do not return the amplifier to your dealer without contact-  
ing customer support first.  
• Never plug this unit in to a dimmer pack  
• Always be sure to mount this unit in an area that will allow  
proper ventilation. Allow about 6” (15cm) between this device  
and a wall  
• Do not attempt to operate this unit, if it becomes damaged  
• This unit is intended for indoor use only, use of this product out-  
doors voids all warranties  
• During long periods of non-use, disconnect the unit’s main  
power  
Installation: This amplifier is designed to mount into a standard  
19” rack. The front panel provides four holes used to screw the  
unit into a rack. The unit also provides a way to rear mount the  
unit into a rack for added security. Rear mounting the unit is espe-  
cially recommended for this amplifier if the unit is to mounted into  
a mobile rack.  
• Always mount this unit in a safe and stable manner  
• Power cords should be routed so they are not likely to be  
walked on, pinched by items placed upon or against them.  
• Cleaning -The outside of the unit should be wipe down with a  
soft cloth and mild cleaner when needed.  
• Heat -The appliance should be situated away from heat sources  
such as radiators, heat registers, stoves, or other appliances  
(including amplifiers) that produce heat.  
• The fixture should be serviced by qualified service personnel  
when:  
Customer Support:
American Audio
® provides a toll free custom-  
er support line, to provide set up help and to answer any question  
should you encounter problems during your set up or initial opera-  
any comments or suggestions. For service related issue please  
contact American Audio
®. Service Hours are Monday through  
Friday 9:00 a.m. to 5:00 p.m. Pacific Standard Time.  
A. The power-supply cord or the plug has been damaged.  
B. Objects have fallen, or liquid has been spilled into the unit.  
C. The appliance has been exposed to rain or water.  
D. The fixture does not appear to operate normally or exhibits a  
marked change in performance.  
Voice:  
Fax:  
(800) 322-6337  
(323) 582-2610  
E-mail:  
 
Front Panel Control  
1
2
3
4 5 6  
8
9 1011 12  
13  
MONO STEREO BRIDGE  
LIMIER  
LIMITER  
ON  
POWER  
ON  
OVER HEAT  
PROTECT  
CLIP  
ON  
-5dB  
-10dB  
OFF  
-15dB  
SIGNAL  
0
10  
0
10  
PROFESSIONAL POWER AMPLIFIER  
Diagram 1  
7
14  
1. Power Switch - This switch is used to control the units main power.  
2. Channel 1 Gain Control - This rotary knob is used to control the out-  
8. Function Indicators -
These indicators detail the operating mode of  
the amplifier. These LEDs will also function as a power indicator.  
put signal of channel one. Turning the knob in a clockwise direction will 9. Channel 2 Overheat Indicator - This indicator will begin to glow  
increase signal output.  
when the channel goes into thermal protection mode. When the unit  
goes into thermal protection, channel output will turn off. See “Thermal  
Protection” page 13.  
3. Channel 1 Limiter Switch -
This is used to activate the channels  
built-in limiter. The limiter reduces the average input level when the sig-  
nal begins to distort, this process is designed to reduce distortion and 10. Channel 2 Protect Indicator - The red Protect LED will begin to  
protect the speakers. See limiter page 12.  
glow when the channel goes into protect mode. When the channel goes  
into protect mode all output for that channel will turn off. This is to pro-  
tect any speakers connected to the channel.  
4. Channel 1 Clip Indicator - This red LED will begin to flash when  
channel one begins to overload (clip). At this point channel one will be-  
gin to distort. Under heavy clipping activity lower the channel one gain 11. Channel 2 Clip Indicator - This red LED will begin to flash when  
control to reduce the risk of damage to your speakers and amplifier. This channel one begins to overload (clip). At this point channel one will be-  
LED may glow when the unit has been turned off, this is normal.  
gin to distort. Under heavy clipping activity lower the channel one gain  
control to reduce the risk of damage to your speakers and amplifier. This  
LED may glow when the unit has been turned off, this is normal.  
5. Channel 1 Protect Indicator - The red Protect LED will begin to glow  
when the channel goes into protect mode. When the channel goes into  
protect mode all output for that channel will turn off. This is to protect any 12. Channel 2 Limiter Switch -
This is used to activate the channels  
speakers connected to the channel.  
built-in limiter. The limiter reduces the average input level when the sig-  
nal begins to distort, this process is designed to reduce distortion and  
protect the speakers. See limiter page 12.  
6. Channel 1 Overheat Indicator - This indicator will begin to glow  
when the channel goes into thermal protection mode. When the unit  
goes into thermal protection, channel output will turn off. See “Thermal 
13. Channel 2 Gain Control -
This rotary knob is used to control the  
Protection” page 13.  
output signal of channel two. Turning the knob in a clockwise direction  
will increase signal output.  
7. Channel 1 Signal Indicators - These green and yellow LED’s will glow  
according to the average signal output.  
14. Channel 2 Signal Indicators - These green and yellow LED’s will  
glow according to the average signal output.  
 
Rear Panel Control  
17  
20 22  
24 26 27  
25  
15  
16 18 19 21 23  
15  
Diagram 2  
28  
29  
32 33  
The amplifier can operate in three different modes; Mono Bridge, Parallel  
Mono, or Stereo. The amplifier is shipped in stereo mode.  
15. Cooling Fans - Dual high speed cooling fans  
16. Channel 2 TRS Input - Channel two 1/4” female jack. Excepts ei-  
ther a balanced or unbalanced plug. See page 7 for more details.  
26. Channel 1 XLR THRU Jack - This jack is used to send a parallel  
signal from the channel one input jacks to another device or amplifier.  
17. Channel 2 XLR Input - Channel two 3-pin XLR balanced input jack.  
27. Fuse Holder - This holder houses the external 20 amp fuse. Always  
replace with the exact same type fuse unless otherwise instructed to do  
so by an authorized American Audio®
service technician.  
See page 7 for more details.  
18. Channel 2 Subwoofer Mode On/Off Switch -
T
u
rns the subwoofer  
mode for channel two on and off.  
28. Channel 2 Speakon Output - Optional speaker output connections.  
Use pins 1+ and 1- of this 4-pole Speakon connector to connect to your  
speaker’s Speakon input jack.  
19. Channel 2 Frequency Adjustment - This knob is used to adjust the  
frequency level sent to your speaker on channel two when running the  
channel in subwoofer mode.  
29. Channel 1 Speakon Output - Optional speaker output connections.  
Use pins 1+ and 1- of this 4-pole Speakon connector to connect to your  
speaker’s Speakon input jack.  
20. Channel 1 XLR input - Channel one 3-pin XLR balanced input jack.  
See page 7 for more details.  
21. Channel 1 Frequency Adjustment - This knob is used to adjust the  
frequency level sent to your speaker on channel one when running the  
channel in subwoofer mode.  
30. Channel 2 Output Jack/5 way Binding Post - Connect to your  
speaker’s input jack. Red is positive signal and Black is negative signal.  
31. Channel 1 Output Jack/5 way Binding Post - Connect to your  
speaker’s input jack. Red is positive signal and Black is negative signal.  
22. Channel 1 TRS Input - Channel one 1/4” female jack. Excepts ei-  
ther a balanced or unbalanced plug. See page 7 for more details.  
32. Ground Lift Switch - This switch is used to disconnect the internal  
ground signal from the amplifier’s chassis ground. This may reduce the  
buzz that is sometimes caused from an electrical 60Hz cycle.  
23. Channel 1 Subwoofer Mode On/Off Switch - Turns the subwoofer  
mode for channel one on and off.  
24. Channel 2 XLR THRU Jack -
This jack is used to send a parallel  
signal from the channel two input jacks to another device or amplifier.  
33. AC Cord - Plug this cable into a standard 110~120v wall outlet. Be  
sure that the supplied voltage in your area matches the amplifiers re-  
quired voltage.  
25. Mode Switch - This switch controls the amplifier’s operating mode.  
 
Set Up  
INPUTS - The V4000plus amplifier allows you to use two types of input connector per a channel, a XLR jack for balanced connections  
and a 1/4” female jack that will accept balanced and unbalanced connectors. Use these connections to connect the output signal from  
a mixer, cross-over or EQ to your V4000plus amplifier. A balanced connection is recommended for cable runs longer that 20ft. When  
constructing your own XLR cables follow the pin configuration describe below for proper connections. For cable runs shorter than  
20ft. you may choose the 1/4” unbalanced input option. The 1/4” unbalanced input option may be more convenient for most users  
due to the abundant supply of prefabricated cables available at your local audio dealer. You may use the two XLR “Input Thru” jacks  
to jump a parallel connection to another amplifier or other device. For Example: Connect a XLR cable to the input of channel one. You  
may now connect a XLR cable from the channel one “Input Thru” jack to the input jack of another amplifier’s channel one input. This  
will reduce the use of “Y” cables.  
Male XLR Pin Configuration:  
Balanced TRS 1/4” Plug  
Unbalanced TS 1/4” Plug  
US ITT Standard  
3
1
Diagram 3  
gram 4  
2
agram 5  
Hot (+)  
Negative (-)  
Ground/Shield  
Hot (+)  
1 Ground/Return/ 0v)  
2 Hot (+ data)  
3 Negative (- data)  
Negative (-)  
OUTPUTS:  
Binding Post/Banana Plug - Connect your speakers to the binding post outputs on the rear of the amplifier. The  
speaker wire may be connect by bare wire (directly connected, usually for permanent connections), banana plug,  
or spade connector. Connections are made to Channels 1 and 2 output’s for stereo mode or across the red termi-  
nals of Channels 1 and 2 for Mono Bridge Mode.  
Important Notice: Although a speaker will operate with the positive and negative leads plugged into either termi-  
nal on the amplifier binding post, be sure to plug the negative lead into the black terminal and positive lead into  
the red terminal. Ensuring proper polarity will avoid speakers being out of phase, that can cause a loss of bass  
response.  
Diagram 8  
Important Notice: Banana Plugs - When connecting your speakers to the amplifier using banana jacks; Be sure that the red and black  
caps on the binding post are completely screwed in. Insert the banana jacks into the caps of the binding post, be sure that the banana  
jack is inserted securely to avoid the risk of it popping out.  
 
Diagram 10  
Bare Wire Connections:  
When connecting your speakers to the amplifier using bare wire; Unscrew the red and black  
caps on the binding post, be sure not to completely remove or unscrew the red and black  
caps. Strip back the wire insulation 1/2” (13mm). Insert the bare wire into the hole that was  
reveled by unscrewing the binding post cap. After inserting the wire into the binding post hole,  
screw the binding post cap down on the wire. To reduce the risk of shock or damage to your  
amplifier, be sure that the wire connected to one binding post does not come in contact with  
that of anothe
r
.  
Typical speaker output using bare wire. Insert  
bare wire into the binding post and tighten.  
Spade Connector: (Diagram 6)  
When connecting your speakers to the amplifier using spade connector; Unscrew the red and black caps on  
the binding post, be sure not to completely remove or unscrew the red and black caps. Insert the spade con-  
nector in to the binding post and tighten the caps down on the spade connector. To reduce the risk of shock  
or damage to your amplifier, be sure that the wire connected to one binding post does not come in contact  
with that of another.  
When connecting your speakers to the amplifier using banana jacks; Be sure that the red and black caps on  
the binding post are tighten down completely. Insert the banana jacks into the caps of the binding post, be  
sure that the banana jack is inserted securely to avoid the risk of it popping out.  
Diagram 11  
Mono Bridge Connections:  
Mono bridge operation connections will follow the above descriptions however, when operating in mono  
bridge operation the speaker connections will run between the two positive (red) leads. Use channel two pos-  
itive output terminal for the negative connection and the channel one positive output terminal for the positive  
connection.  
Typical speaker output using  
spade connectors. Insert  
bare wire into the binding  
post and tighten.  
Stereo Connections Using the Neutrik Speakon output connectors:  
Recent regulatory requirements in Europe have outlawed the use of the dual banana plug and force amp users to terminate their speaker  
cables with spade lugs or bare wire ends. This is not advantageous to most users that want to reconfigure their systems or quickly  
change out an amp. The Neutrik Speakon® connector provides the most convenient solution to this problem, eliminating the need for  
spade lugs or bare wire end cables. Major speaker manufacturers have been using Speakon connectors on their products for years,  
so chances are you are ready to use the Speakon connection. With Speakon connectors, you can connect straight from the amplifier  
to the speaker. The Speakon connector used on this amplifier meets all known safety regulations. Once wired correctly, the connector  
cannot be plugged in backwards, causing the type of inverted polarity situations that have become common with banana hookups. This  
connection will provide a safe, secure and reliable method of connecting your speakers to your new amplifier. You can purchase the  
Speakon® NL4FC connectors from your local audio dealer.  
 
OPERATING MODES:
Always configure your amplifier operating mode before beginning operation. If you want to change it dur-  
ing performance. You must decrease the gain controls to their lowest levels to protect the speakers from any popping noise.  
Stereo Operation - Page 10/Figure 9 details an example of a typical stereo set-up. Connect your inputs into channels one and  
two of the amplifier. Connect your speakers to the outputs on the rear of the amplifier. Be sure that your front gain controls are turned  
down to their lowest level (full counter-clockwise). Turn your amp on. Turn your input source level up. Use your front gain controls to  
regulate the output volume. Be sure not to raise the volume to the clip level, however an intermittent clip signal is acceptable.  
Mono Bridge Operation - Page 9/Figure 8 details a mono bridge set-up. Be sure your amplifier and all other audio equipment  
is powered down. Flip the Stereo/Mono Bridge switch to the Mono Bridge position. Connect an input signal to channel one. Connect  
your speaker across the red output binding post on the rear of your amplifier. Turn your equipment on (your amplifier should always  
be the last item you turn on). Apply an input source signal to your amplifier. Turn channel two gain up. Use the channel one gain to  
regulate your amplifier output.  
Bridged-Mono Mode Caution - The voltage across the output terminals of a bridged V4000plus™ amplifier may equal or exceed  
100 volts RMS and may be as high as 130 volts. Use fully insulated CLASS ONE wiring, and the load must be rated for up to 2500 watts  
(@4 ohms)  
Parallel Mono - “Parallel ” ties the two channel line inputs together so that they will both be driven by the same signal, without the  
need for external jumpers or wiring. Both amplifier channels will operate independently. Though they carry the same signal, their gain  
controls affect only their respective channels, and they both must use their respected speaker outputs. Never attempt to parallel the  
speaker outputs, this may cause serious damage to your amplifier! This mode is recommended when using the V4000plus™ to run bass  
speakers, to achieve better low end. To run in parallel mono mode connect your system as you would if you were going to run in stereo  
mode. Then flip the mode switch to “MONO.” Be sure the amp is off or the power is disconnected before making any changes.  
Subwoofer Mode -
This mode sends low frequencies to your speakers without the use of an external cross-over. The subwoofer  
operation can be operated in stereo, mono, or bridge mono modes. Change the different operating modes by flipping the mode switch  
on the rear of the unit to your desired operating mode. Also, set the subwoofer mode switch to the subwoofer position. Use the frequency  
selector to adjust the subwoofer output frequency from 20Hz to 200Hz. The different subwoofer modes are listed as follows;  
Bridge Subwoofer - This operation allows you to get the most possible power out of your amplifier for the sole purpose of running a  
high powered subwoofer loudspeaker in mono. To avoid amplifier overheating, never run the amplifier below 4 ohms in this mode. In  
this mode you may use the frequency adjustment on the rear of the amp, to control the frequency output level. Frequencies may be  
adjusted from 20Hz to 200Hz. Figure 14 details a typical Bridge Subwoofer set up.  
Stereo Subwoofer - This operation is similar to the Bridge Subwoofer operation but in stereo. This operation allows you to run several  
subwoofers down to a minimum of 2 ohms. To avoid amplifier overheating, never run the amplifier below 2 ohms in this mode. Set  
up this mode as you would a standard stereo set up. Be sure both channels are set to “SUBWOOF.” In this mode you may use the  
frequency adjustment on the rear of the amp, to control the bass frequency output level. Frequencies may be adjusted from 20Hz to  
200Hz. Figure 15 details a typical Stereo Subwoofer set up.  
 
Mono Subwoofer -
This operation is similar to the Stereo Subwoofer operation but in mono. When running subwoofers it is usually  
recommended to run them in mono mode to achieve a cleaner tighter low end. This operation allows you to run several subwoofers  
down to a minimum of 2 ohms. To avoid amplifier overheating, never run the amplifier below 2 ohms in this mode. Set up this mode  
as you would a standard stereo set up. Be sure both channels are set to “SUBWOOF” and the mode switch is set to “MONO.” In this  
mode you may use the frequency adjustment on the rear of the amp, to control the bass frequency output level. Frequencies may be  
adjusted from 20Hz to 200Hz.  
One Channel Normal/One Channel Subwoofer (BI-AMP) - You may also use your amp to bi-amp your system. You may use one  
side of the amp to power a subwoofer and the other side to power a full range speaker. Follow the set up guides listed above to mix  
and match your operations.  
PROTECTION:  
Limiter - The V4000plus™ series comes with a built in limiter. When the input signal overloads, the “CLIP LED’s” indicate a signal  
overload, at this time, the master volume should be lowered to reduce distortion. If the input gain level is not reduced the built-in lim-  
iter will activate. During signal overload, the limiter will reduce the input audio signal enough to minimize the amount of clipping. A  
limiter takes the gain of an overloading signal and reduces it, the reduction in gain reduces distortion that can cause damage to your  
speakers and amplifier. During normal operation below clipping, and momentary clips on peaks, the limiter does not affect the audio  
signal and is inaudible. It will allow brief clipping of peaks and will only activate when continuous, hard clipping occurs. During exces-  
sive clipping the limiter will reduce the audio signal enough to minimize the amount of clipping. When the input signal decreases  
enough that clipping ends, the limiter will deactivate and cease its gain reduction. The limiter has a fixed threshold and can not be  
adjusted.  
Safe Power Levels at Different Output Loads:  
8-Ohm Loads: The amplifier can operate at practically any power level without risk of overheating. However, if it is pushed hard  
enough to continually light the “CLIP ” indicator, the amplifier’s average output power can reach 150 watts.  
4-Ohm Loads:
If the “CLIP” indicator flashes occasionally, the amplifier is approaching its maximum long-term power capacity. If it is  
lit about half the time, the amplifier channel will probably go into thermal protection within a few minutes.  
2-Ohm Loads:
Except for an occasional flash, keep the “CLIP” indicator dark to avoid overheating the amplifier channel. Clipping  
should be kept to a reasonable minimum. An amplifier’s peak current draw at full output power into 2 ohms is several times what the  
“normal ” draw is, but its various protection circuits will prevent this condition lasting more than a minute or two.  
Short Circuit Protection -
The V4000
plus™ series amplifiers all come with built-in Output Short  
Circuit Protects. The Output Short Circuit Protection protects the output devices of the amplifier  
from short circuits and stressful loads. If your speaker lines short, the amplifier automatically detects  
this problem and discontinues operation for that channel. If one side of your amplifier becomes  
shorted and goes into protect mode, the other side will continue to operate normally. During short  
circuit protection, the "Clip" LED and “Protect" LED will light simultaneously indicating amplifier  
fault. All channel output during the “Short Circuit Protection" will be interrupted (i.e. no sound out-  
 
put).
Short Circuit Protection
can usually be traced back to the signal output line (i.e. speaker line). Check the line from the output  
terminal of the amplifier to the speaker. If this line good, check the internal speaker connections and components. A short circuit will  
usually be traced to a bad cable or a bad speaker component and is rarely traced to the amplifier itself.  
Thermal Protection -
Dual variable speed fans on the V4000plus amplifier provide adequate cooling. During low level output the fans  
run at normal speeds. During high output and as heat raises, (exceeding 90°C.), the fans will run at higher speeds to aid the cooling  
process. If the heatsink temperature exceeds 91°C., the amplifier will mute until the amplifier cools down. When the amplifier cools  
below 90°C., the amplifier will return to normal operations. Be sure not to operate your amplifier below the minimum load ratings to  
reduce the risk of overheating problems.  
Input/Output Protection - The input circuits are isolated by 10k resistors. An ultrasonic network uncouples
RF
from the output and  
helps keep the amplifier stable with reactive loads.  
Operating Voltage (AC Mains) - The serial number label indicates the correct AC main voltage. Connecting to the wrong voltage is  
dangerous and may damage the amplifier. Always be sure the source voltage for your areas matches the required voltage for your  
amplifier.  
Gain Controls -
The gain controls are located on the front panel and are calibrated in 2dB of attenuation from full gain. It is best to  
adjust the amplifier so no “hissing” is heard from speakers with no music being played, this will ensure the lowest possible distortion  
during normal operation.  
AMPLIFIER FE
A
T
URES:  
THRU -
Thru will allow the user to daisy-chain one amplifiers signal input into another amplifier. Plug the signal source outputs into the  
first amplifier’s input, patch from the amplifier’s THRU jacks to the next amplifier’s input, and so on, daisy-chaining as many amplifiers  
as there is no excessive level loss. Is not affected by crossover setting.  
GROUND LIFT SWITCH - Applying or lifting the ground switch will change the level for background noise and hum, if the noise level  
remains the same in either position, it is better to keep the ground lift switch in the ground position. This will eliminate 60Hz cycle hum  
that is sometimes induced when mounting several units in the same rack.  
OPERATING VOLTAGE (AC MAINS) - The serial number label indicates the correct AC main voltage. Connecting to the wrong voltage  
is dangerous and may damage the amplifier.  
GAIN CONTROLS - The gain controls are located on the front panel and are calibrated in 2dB of attenuation from full gain. It is best to  
adjust the amplifier so no “hissing” is heard from speakers with no music being played, this will ensure the lowest possible distortion  
during normal operation.  
LED INDICATORS - Each channel has seven LEDS. Four LEDs indicate signal level activity; two green LED and two yellow LED. One  
red LED indicates signal clipping. One red LED indicates protections mode for shorts/ overload. One red LED indicating overheating  
situations. Both channels will also share the center green LED that indicate the amplifier operating mode.  
FUNCTION INDICATORS - These green LED indicators detail the amplifiers current operating mode (Stereo, Mono, or Bridge).  
 
OVERHE
A
T
I
NDIC
A
T
OR -
Two red LED’s for this function, one for each  
channel. When the amplifier’s heat sink temperature rises above 91° C.,  
output will be discontinue and the red overheat LED glow continuously. One  
channel can still operate normally if the other goes into overheat protection  
mode.  
Figure 10  
Brass Inserts  
4-Conductor Speaker Cable  
SPEAKON ASSEMB
L
Y:
You will need a pair of Neutrik Speakon®
NL4FC  
connectors. You will also need high-quality two or four conductor speaker  
cable, a pair of needle-nosed pliers and a 1.5-mm Allen key to assemble the  
Speakon connectors to your speaker wire. To assemble the Neutrik Speakon  
NL4FC connector, complete the following steps:  
Figure 11  
1. Strip back 3 /4-inch of the cable casing. Strip off 1 /4-inch from the end of  
each of the conductors down to bare wire, and insert the brass fittings ( Figure  
10).  
2. Slide the cable tension clip (D) and the speakon coupler (E) through the  
cable end. See figure 11.  
A
B
C
D
E
3. Insert each wire with the brass fittings into the top of appropriate slot of the  
connector insert (B) as shown in figures 11 and 12. Use a 1.5-mm Allen key to  
tighten the connection (Figure 12).  
Figure 12  
4. Be sure to properly match the positive (+) and negative (–) leads of each  
wire (Figure 13).  
5. Slide the connector insert (B) into the connector housing (A), making sure  
that the large notch on the outer edge of the insert lines up with the large  
groove on the inside of the connector housing. The insert should slide easily  
through the housing and out the other side until it extends approximately 3  
/4-inch from the end of the housing.  
6. Slide the cable tension clip (D) along the cable and insert into the housing  
(A), making sure that the large notch lines up with the large groove on the  
inside of the connector housing (A). The cable tension clip (D) should slide  
easily into the housing until only 3 /8-inch of the cable tension clip (D) extends  
from the back end of the connector.  
Figure 13  
INPUT BA ANCE  
SPEAKON 1+ HOT  
1
COLD  
UTPUTS  
C
2
1
-
+2  
+1  
-1  
+2  
+1  
7. Slide the coupler (E) along the cable and screw it onto the end of the  
housing (A). Before tightening, you may want to test the connector to make  
sure it has been assembled properly.  
+2  
-1  
+2  
+