US Amps AX User Manual

AX seriess  
Owners Maannuuaall  
and  
Installation  
Guide  
Copyright 2007 U.S.Amps. All rights reserved.  
Did You Buy the Right U.S.Amp?  
There is a U.S.Amp for every purpose! From raw power to exquisite sound quality and everything  
in between, U.S.Amps offers state-of-the-art technology to meet your every need.  
INSTALLATION  
Amplifier Mounting: Choose an appropriate location to mount the amplifier(s). Make  
sure your choice is free from excess heat, moisture, and vibration. Under the vehicle seat or in the  
trunk are common mounting locations. Be sure the amplifier receives adequate ventilation to its  
heat sink and is positioned away from flying luggage and people’s feet. Do not mount to the  
speaker enclosures.  
Ventilation: It is important to provide the amplifier with adequate ventilation to remove  
heat from the amplifier heat sink. During high performance applications, in which the amplifier  
may be exposed to extremely low impedance loads, it may be necessary to provide external  
ventilation via a fan or some other means. With proper ventilation, the "run time" of the amplifier  
between thermal protection cycles can be greatly extended.  
IMPORTANT NOTICE  
The Input of a U.S.Amp MUST be GROUNDED for proper amplifier operation.  
The use of external ground isolation dividing devices is UNNECESSARY  
and may cause severe amplifier and/or system damage.  
Amplifier Input: U.S.Amps feature a unique isolated input section that will accept  
signal voltages from 1 to 9 volts. The input section also provides amplifier ground isolation for the  
prevention of system and engine noise. The unique configuration of the U.S.Amps input necessi-  
tates a correct input ground, and is not compatible with external ground isolation devices.  
Signal Level (BTL) Input: This product will accept line and signal level, and can be  
used with most BTL "high powered" sources. To use a BTL source, observe the following:  
1) BTL outputs have two "hot" non-grounded leads per channel. Select ONE per channel, and  
connect it to the “center conductor” of the RCA input cables going to the amplifier input.  
2) Insulate and disregard the second wire of each BTL output pair.  
3) Ground the shield wires of the RCA cable to the metal body of the source unit.  
Gain Control Adjustment: Always start with the gain control fully counter-clockwise  
(all the way down), or just slightly open. Adjust the source unit volume as high as possible without  
distortion. Increase the amplifier gain until the amplifier distorts, then turn the gain down slightly  
until the signal becomes clear. It is desirable to operate the amp at the lowest possible gain setting  
to help reject spurious system noise.  
2
CARE AND FEEDING OF YOUR BATTERIES  
As mentioned before, most batteries are built for the relatively light chore of starting the  
engine. Unless you have the room and ambition to install an upgraded high-powered alternator,  
your system current requirements may exceed the charging capability of your car’s electrical  
system. When this happens, you have to rely on the vehicle battery(s) to make up the  
difference. Another factor to consider is voltage. Although the electrical system is considered to  
be “12 volt, the battery, when healthy, actually “rests” at 12.6 volts. The average alternator  
“puts out” 14.4 volts when the engine is on, because it is necessary to “feed” a battery higher  
voltage in order for it to charge.  
GETTING WIRED:  
Once you have established the current needs of your system, it will be of the UTMOST  
IMPORTANCE to properly fuse the amplifier. Remember, power connections are always the last  
thing. There cannot be enough emphasis placed on the importance of proper fusing. Fuses  
prevent catastrophes. Always fuse each U.S.Amp product at or less than the recom-  
mended amperage. Another major consideration is wire. If you wish to build a truly high-  
powered system, you must take into account the total amperage requirements of the system  
and select your wire gauge accordingly. The following chart can be used as a guide:  
WIRE GAUGE and AMPERAGE Guide:  
AWG 14  
AWG 13  
30 Amps  
35 Amps  
AWG 6  
AWG 4  
80 Amps  
AWG 0  
190 Amps  
215 Amps  
105 Amps  
AWG 00  
AWG 10  
AWG 8  
45 Amps  
60 Amps  
AWG 2  
AWG 1  
135 Amps  
160 Amps  
AWG 000  
245 Amps  
275 Amps  
AWG 0000  
These are real numbers, right out of the 1951 U.S.Federal Electronics Code Book.  
It takes real wire to do real work.  
For each 100 watts, when playing music, count on 10 amps average of average current draw.  
3
AX-TU600C  
2-Channel Amplifiers  
Controls and Features  
5
6
7
8
2
3
1
4
Off  
On  
HP  
Full  
LP  
Pwr Prot  
L
Min  
50 500  
500  
SUB  
Subsonic 50  
HP  
INPUT SUB  
XOver  
Filter  
Freq  
Gain Freq  
AX-TUR6BG00C  
R
In  
Out  
U.S.A.  
“VTCSD” Technology  
Amplifier Input The amplifier MUST receive input on BOTH RCA jacks  
1
for proper operation.  
2 Amplifier Output The low level output can be connected to other amplifiers.  
3
4
Input Gain is variable from 1 to 9 volts for full output. Best results are achieved by  
adjusting the control to the lowest setting in relation to the output of the source unit.  
Low-pass Crossover Control  
For the internal amplifier, adjustable from 50 Hz to 500 Hz @ 24dB.  
5 Remote Bass Gain A phone jack that accepts the included RBG control harness  
to allow the amplifier volume to be controlled from the passenger compartment.  
6 Low-pass Crossover 3-way Switch  
A 3-way switch which selects the full-range/high-pass/low-pass crossover feature.  
7
8
Subsonic Filter To optimize amplifier power in the audible frequencies, a defeatable  
36 Hz subsonic filter provides a 6 dB per octave roll-off.  
High-pass Crossover Control  
For the internal amplifier, adjustable from 50 Hz to 500 Hz @ 12dB.  
WARNING: All U.S.Amps require a grounded input connection.  
DO NOT use ground-loop isolation devices or high/low conversion devices  
on the input of your U.S.Amp!  
4
AX-1000/2000  
2-Channel Amplifiers  
Controls and Features  
5
6
7
2
3
1
4
Off  
On  
Off  
On  
Pwr Prot  
L
Min  
50 500  
SUB  
XOver  
Subsonic  
Filter  
INPUT SUB  
Gain Freq  
RBG  
R
AX-1000  
In  
Out  
Two Ohm Stable Design  
U.S.A.  
(Shown here is AX-1000, but the diagram is also applicable to AX-2000.)  
Amplifier Input The amplifier MUST receive input on BOTH RCA jacks  
1
for proper operation.  
2 Amplifier Output The low level output can be connected to other amplifiers.  
3
4
Input Gain is variable from 1 to 9 volts for full output. Best results are achieved by  
adjusting the control to the lowest setting in relation to the output of the source unit.  
Low-pass Crossover Control  
For the internal amplifier, adjustable from 50 Hz to 500 Hz @ 24dB.  
5 Remote Bass Gain A phone jack that accepts the included RBG control harness  
to allow the amplifier volume to be controlled from the passenger compartment.  
6 Low-pass Crossover On/Off Switch  
A 2-way switch which enables/disables the low-pass crossover feature.  
7
Subsonic Filter To optimize amplifier power in the audible frequencies, a defeatable  
36 Hz subsonic filter provides a 6 dB per octave roll-off.  
WARNING: NEVER use ground-loop isolation  
on the input of your U.S.Amp! It doesn’t need it!  
5
AX-TU4360C  
4-Channel Amplifiers  
Controls and Features  
The AX-4360C features a selectable two-way electronic crossover with independent  
front and rear mid-high frequency adjustment and 2 ohm per channel stability. Power is  
provided by four 75 watt channels that can be bridged as front and rear pairs into a 4  
ohm load for a total of 180 watts per bridged pair.  
WARNING: NEVER use ground-loop isolation  
on the input of your U.S.Amp! It doesn’t need it!  
5
2
3
1
4
Front Rear Front Rear  
Gain Gain  
Freq Freq  
SUB  
Freq  
LP HP Full  
LP HP Full  
Pwr Prot  
L
Front  
Rear  
Max  
Max  
50 500 50 500 50 500  
AX-TU44360C RBG  
R
Front Rear  
Input Input  
Four Channel Amplifier  
U.S.A.  
Amplifier Input The amplifier MUST receive input on BOTH RCA jacks  
1
for proper operation.  
2 Input Gain is variable from 1 to 9 volts for full output. Best results are achieved by  
adjusting the control to the lowest setting in relation to the output of the source unit.  
3 Low-pass Crossover Control  
For the internal amplifier, adjustable from 50 Hz to 500 Hz @ 24dB.  
4
5
Remote Bass Gain A phone jack that accepts the included RBG control  
harness to allow the amplifier volume to be controlled from the passenger compartment.  
Low-pass Crossover 3-way Switch  
A 3-way switch which selects the full-range/high-pass/low-pass crossover feature.  
6
AX-5600  
5-Channel Amplifier  
Controls and Features  
The 5-channel AX-5600 features a selectable 3-way electronic crossover with independent  
front and rear mid-high frequency adjustment, dual power supplies, 2 ohm per channel  
stability, and a Remote Bass Gain.  
WARNING: NEVER use ground-loop isolation  
on the input of your U.S.Amp! It doesn’t need it!  
1
Rear  
Gain  
Front  
Gain  
Sub  
Sub  
Band  
Pass  
Rear  
HP  
Gain XOver  
L
L
Min  
50 500  
200 5K  
Rear LP  
XOver  
50 500  
Rear HP  
XOver  
Max  
50 500  
Front HP  
XOver  
Max  
Pwr  
RBG  
R
R
AX-5600  
Rear  
Input  
Front  
Input  
Five Channel Amplifier  
DE Sub Channel  
SUB Input  
U.S.A.  
2
1
2
Remote Bass Gain The AX-5600 comes with an optional “Remote Bass Gain” or “RBG” that  
can be mounted in the passenger compartment to independently attenuate the low pass output.  
The “BASS GAIN” located on the terminal endplate of the unit is used both to set the level at the  
low pass output and control the range of the RBG.  
3-WAY Input allows the AX-5600 to accept input from modern 3-way head-units  
allowing front to-rear fading of the mid-highs and Independent frequency and volume adjustment  
from the passenger compartment.  
2 Ohm Stability  
All 5 channels of the AX-5600 are stable  
to 2 ohms. The power of the mid-high  
channels increase 17% from 4 to 2 ohms  
while the subwoofer channel increases a  
whopping 43%!  
Protection AX-5600 is protected against  
thermal, over and under voltage and short  
circuit. The separate power supplies of AX-5600  
are individually protected against over-current.  
Amp Power @ 4 Ohms  
75 W X 4 + 500 W X 1 @ 1Ω  
800  
Total Watts  
Amp Power @ 2 Ohms  
90 W X 4 + 500 W X 1 @ 1Ω  
860  
Total Watts  
7
AX-600DE/3200DE  
Class “DE” Amplifiers  
Controls and Features  
1
2
3
4
5
Subsonic  
Slave  
PWR Prot  
L
Class DE Digital Amplifier  
Min  
INPUT  
Gain  
50 500  
SUB  
Freq  
XOver  
U.S.A.  
RBG  
R
AX-600DE  
1200 Watts Dynamic Power  
600 Watts RMS Power  
INPUT  
One Ohm Stable Design  
(Shown here is AX-600DE, but the diagram is also applicable to AX-3200DE.)  
Amplifier Input The amplifier MUST receive input on BOTH RCA jacks for proper  
operation.  
1
2
Input Gain is variable from 150 mV to 3 volts for full output. Best results are achieved  
by adjusting the control to the lowest setting in relation to the output of the source unit.  
3 Low-pass Crossover Control  
For the internal amplifier, adjustable from 50 Hz to 500 Hz @ 24dB.  
4 Remote Bass Gain A two-position removable plug that accepts the included RBG  
control harness to allow the amplifier volume to be controlled from the passenger  
compartment.  
5 The Magic Switch The far left "Subsonic Filter" position makes more efficient use of amplifier  
power by discarding frequencies below 36Hz.  
The center "XOver" defeats the Subsonic Filter tor amplifier operation down to 5 Hz.  
The far right "Slave" position defeats all amplifier controls to receive information through the Remote  
Bass Gain wires from another "master" amplifier.  
This can be repeated as often as necessary with all slave units receiving Identical gain, frequency, and  
subsonic functions from the master amplifier.  
A single Remote Bass Gain can be connected at any point to universally control the volume of the  
entire amplifier bank.  
WARNING: All U.S.Amps require a grounded input connection.  
DO NOT use ground-loop isolation devices or high/low conversion devices  
on the input of your U.S.Amp!  
8
Wiring Instructions for AX-TU600C/1000/2000  
Power Output  
+
AX-TU600C  
165W X 2 @ 4Ω  
300W X 2 @ 2Ω  
AX-1000  
+
300W X 2 @ 4Ω  
500W X 2 @ 2Ω  
AX-2000  
600W X 2 @ 4Ω  
1000W X 2 @ 2Ω  
LEFT  
[—]  
LEFT RIGHT RIGHT  
[+] [—] [+]  
+
Source Unit  
+
Positive 12V Remote Turn-on  
Bridged Output  
AX-TU600C  
600W X 1 @ 4Ω  
AX-1000  
Fuse Rating  
1000W X 1 @ 4Ω  
AX-2000  
AX-TU600C: 60A  
AX-1000: 100A  
AX-2000: 200A  
12V  
POS  
REM  
GND  
2000W X 1 @ 4Ω  
+
Negative 12V to Vehicle Ground  
(Use minimum 8-gauge Wire)  
F
U
S
E
+
Vehicle Battery  
WARNING: NEVER use ground-loop isolation  
11 to 15 volts DC  
on the input of your U.S.Amp! It doesn’t need it!  
Vehicle Ground  
9
Wiring Instructions for AX-TU4360C  
Source Unit  
WARNING: NEVER use ground-loop isolation  
on the input of your U.S.Amp! It doesn’t need it!  
Positive 12V Remote Turn-on  
Front Left  
Speaker  
Front Right  
Speaker  
12V  
POS  
REM  
GND  
+
+
+
Positive 12V  
to Vehicle Battery  
(Use minimum  
8-gauge Wire)  
FL  
FL  
FR  
FR  
[—]  
[+]  
[—]  
[+]  
Negative 12V  
to Vehicle Ground  
(Use minimum  
8-gauge Wire)  
Power Output  
75W X 4 @ 4Ω  
90W X 4 @ 2Ω  
+
RL  
RL  
RR  
RR  
[—]  
[+]  
[—]  
[+]  
+
F
60A  
U
S
E
+
+
Rear Left  
Speaker  
Rear Right  
Speaker  
+
[4 channel Operation]  
Vehicle Battery  
11 to 15 volts DC  
Vehicle Ground  
+
+
Bridged Output  
180W X 2 @ 4Ω  
FL  
FL  
FR  
FR  
[—]  
[+]  
[—]  
[+]  
+
Left  
Speaker  
Right  
Speaker  
RL  
RL  
RR  
RR  
[—]  
[+]  
[—]  
[+]  
+
[2 channel Operation]  
DO NOT OPERATE AX-4360C BRIDGED MONO  
AT LESS THAN 4Ω PER BRIDGED CHANNEL  
10  
Wiring Instructions for AX-5600  
Source Unit  
WARNING: NEVER use ground-loop isolation  
on the input of your U.S.Amp! It doesn’t need it!  
Front Left  
Speaker  
Positive 12V Remote Turn-on  
Front Right  
Speaker  
+
12V  
POS  
REM  
GND  
+
+
Positive 12V  
to Vehicle Battery  
(Use minimum  
8-gauge Wire)  
Power Output  
75W X 4 @ 4Ω  
90W X 4 @ 2Ω  
Negative 12V  
to Vehicle Ground  
(Use minimum  
8-gauge Wire)  
RL  
RR  
FL  
FR  
SUB  
[—]  
F
[—]  
[—]  
[—]  
[—]  
U
S
E
75A  
+
RL  
RR  
FL  
FR  
SUB  
[+]  
[+]  
[+]  
[+]  
[+]  
+
+
+
Sub Woofer Output  
500W X 1 @ 1Ω  
Vehicle Battery  
11 to 15 volts DC  
Vehicle Ground  
+
+
Rear Left  
Speaker  
Rear Right  
Speaker  
(Note: The front and rear channels of the AX-5600)  
11  
Wiring Instructions for AX-600DE  
SPECIAL NOTE:  
Class “DE” amplifiers are single-ended mono designs,  
and are not bridgeable. BE SURE the TOTAL LOAD of  
ALL connected speakers does not fall beneath 1Ω.  
Choose one of three possible connections shown below.  
1
2
+
+
Source Unit  
Positive 12V Remote Turn-on  
Power Output  
AX-600DE  
250W X 1 @ 4Ω  
400W X 1 @ 2Ω  
600W X 1 @ 1Ω  
LEFT  
LEFT RIGHT RIGHT  
[—]  
[+]  
[—]  
[+]  
+
3
12V  
REM  
GND  
POS  
+
+
Negative 12V to Vehicle Ground  
(Use minimum 8-gauge Wire)  
F
U
S
E
50A  
WARNING: NEVER use ground-loop isolation  
+
on the input of your U.S.Amp! It doesn’t need it!  
Vehicle Battery  
11 to 15 volts DC  
Vehicle Ground  
12  
Wiring Instructions for AX-3200DE  
SPECIAL NOTE:  
Class “DE” amplifiers are single-ended mono designs,  
and are not bridgeable. BE SURE the TOTAL LOAD of  
ALL connected speakers does not fall beneath 1Ω.  
WARNING: NEVER use ground-loop isolation  
on the input of your U.S.Amp! It doesn’t need it!  
Source Unit  
LEFT  
[—]  
LEFT RIGHT RIGHT  
[+] [—] [+]  
+
Positive 12V Remote Turn-on  
+
Power Output  
1200W X 1 @ 4Ω  
2500W X 1 @ 2Ω  
3000W X 1 @ 1Ω  
12V  
POS  
REM  
GND  
+
Negative 12V to Vehicle Ground  
(Use minimum 8-gauge Wire)  
F
U
S
E
+
Vehicle Battery  
11 to 15 volts DC  
Vehicle Ground  
13  
U.S.Amps Amplifier Power & Fuse  
Watts per Channel*  
MODEL  
4 Ω  
2 Ω  
1 Ω  
FUSE  
300W X 2  
500W X 2  
N/A  
100A  
AX-1000  
AX-2000  
600W X 2  
1000W X 2  
N/A  
200A  
75W X 4  
250W X 1  
1200W X 1  
90W X 4  
400W X 1  
2000W X 1  
500W X 1(Sub)  
600W X 1  
75A  
50A  
AX-5600  
AX-600DE  
AX-3200DE  
3000W X 1  
300A  
165W X 2  
75W X 4  
300W X 2  
90W X 4  
N/A  
N/A  
60A  
60A  
AX-TU600C  
AX-TU4360C  
AX-2000HC  
150W X 2  
300W X 2  
N/A  
200A  
Copyright 2007 U.S.Amps. All rights reserved.  
*Specifications are subject to change without notice  
14  
U.S.Amps Amplifier Specification  
Bridged  
Output  
THD  
@ 4Ω  
S/N  
Ratio  
Damping  
Factor**  
Slew  
Rate  
MODEL  
AX-1000  
1000W X 1 @ 4Ω  
<0.025% >95 dB  
<0.025% >95 dB  
>600  
150 Vus  
150 Vus  
AX-2000  
AX-5600  
AX-600DE  
2000W X 1 @ 4Ω  
>1000  
N/A  
<0.025% >95 dB  
>200  
150 Vus  
Mono  
Mono  
<0.1%  
<0.1%  
>86 dB  
>86 dB  
>250  
>250  
N/A  
N/A  
AX-3200DE  
600W X 1 @ 4Ω  
<0.05%  
<0.05%  
>95 dB  
>95 dB  
>600  
>200  
150 Vus  
150 Vus  
150 Vus  
AX-TU600C  
AX-TU4360C  
AX-2000HC  
180W X 2 @ 4Ω  
600W X 1 @ 4Ω  
2000W X 1 @ 1Ω  
<0.025% >95 dB  
>1000  
Copyright 2007 U.S.Amps. All rights reserved. *Specifications are subject to change without notice.  
**Measured at 4Ω/14.4V at the circuit board.  
15  
Why Tubes?  
You may know that a transistor is a  
modern, efficient, less expensive version of  
a vacuum tube, which is the device that made  
sound recording and reproduction possible in the  
first place. Now, the electronics industry has been  
trying for many years to equal the sound quality available from tubes. They have  
been able to make transistor amps louder, cooler, more abusable, and less expen-  
sive than tubes, but to this day, they’ve been unable to make any solid state amp  
sound as good as a tube amp.  
So, our engineer got to wondering, “What if I combined the sonic character of a  
vacuum tube with the drive capabilities of solid state?”  
Well, the result is the U.S.Amps’ VTCSD hybrid amps. Using the signal path  
directly out of the tubes as a “steering” signal and the following drive signal wave  
from the transistors as the “motor,” with absolutely no negative feedback as a  
corrective to the transistor’s waveform, we achieved the most detailed, pleasing,  
articulated sound available in mobile audio today.  
Tube In, Tube Out  
(Vacuum Tube Current Sync Drive)  
VTCSD  
Hybrid Tube/Transistor Amps  
Uneven Clipping  
Odd-order Harmonics  
Solid State Amplifier  
Preamp Signal  
Solid State Input  
Low Voltage  
Low Current  
Smooth, Low  
Tube Voltage  
Negative Feedback  
Transistor Switching  
Noise  
Listening Fatigue  
Compression  
and Coloration  
Classic Vacuum Tube Amps w/Output Transformer  
e resultant signal  
is soothing and  
pleasing  
High Voltage/Low Current  
Signal from Output Tube is  
Output  
Transformer  
converts  
Voltage  
Energy  
Tube Input  
into  
Low Voltage  
Low Current  
fed into Output  
Transformer  
Yet lacks much of  
the tubes’ original  
dynamic range  
Current  
Vacuum Tube Current Sync Drive  
Positive Current Sync  
Direct Input  
Input signal is fed  
DIRECTLY into the tube.  
ere are no solid state  
gain stages or processors  
in the signal path.  
e original high voltage tube signal is joined by  
a null-gain current following circuit that is pulled  
to the voltage rails by an opposing pair of  
current syncs, providing a sort of amplifier  
“power steering” to deliver speaker-driving  
power without taxing the character of the  
original tube voltage content.  
Negative Current Sync  
16  
VTCSD (continued)  
VTCSD “follows” the high voltage tube signal STRAIGHT INTO THE SPEAKERS,  
adding only current in a form of “amplifier power steering” — free from voltage gain  
or negative amplifier feedback!  
Vaccum tubes are renowned for their high dynamic range and smooth emphasis  
of even-order harmonics. The transformer-less VTCSD circuit brings out hidden  
qualities of the vacuum tubes, including excellent frequency response, smooth  
“clipping” and high signal-to-noise ratio.  
VTCSD divides audio signal amplification in two separate areas, voltage and  
current. By starting with the vacuum tube as a source of high voltage(vacuum  
tubes operate at four times the voltage of transistors), VTCSD adds a second  
solid-state “amperage amplifier.” The “amperage amplifier” is a null-gain circuit  
driven by “current syncs” that mirror the voltage signal and provide “torque” to the  
speakers in perfect synchronization with the voltage content, that neither distorts or  
colors the original tube sound!  
The result are astonishing. All of the intensity, transience, and frequency  
response of the vacuum tube, which can operate at MUCH higher output voltage  
than audio transistors.  
Benefis of Class “DE”  
D
E
U.S.Amps continues to push the technological envelope with the introduction  
of two new digital models that combine the attributes of “D” lass amplifiers  
with the versatility and practical fidelity usualyy expericenced only with  
standard Class “AB” designs. Thsi bold leap forward in digital technology  
allows for 90% effieciency under extreme dircumstances that turn other  
digital amplifiers to toast. As cars become more and more energy efficient  
and provide less available battery power, Class “DE” represents the best  
power output-to-current consumption available on the market today!  
Combines class “D” attributes with the versatility and practical  
fidelity of class “AB” designs  
Allows for 90% efficiency under extreme circumstances that turn  
other digital amplifiers to toast  
Represents the best power output-to-current consumption  
17  
NOTE  
18  
NEVER, NEVER, NEVER!  
NEVER USE A U.S.AMP WITH A GROUND LOOP ISOLATOR ON THE RCA’S OR AN ISOLATED  
INPUT SIGNAL. U.S.Amps are input-isolated at the factory and require an input ground for proper operation.  
NEVER INSTALL OR MOUNT YOUR AMPLIFIER DIRECTLY TO A SPEAKER ENCLOSURE OR  
ANYWHERE ELSE WHERE SEVERE VIBRATION IS PRESENT. Protect your investment. Use Common  
sense. Make sure the spot you choose is well-ventilated and free from dirt and moisture.  
NEVER USE YOUR U.S.AMP BELOW THE RATED MINIMUM IMPEDANCE. Remember, when you bridge  
your amplifier, each channel “sees” one half of the load, hence at 4 ohms bridged each channel is operating at 2 ohms.  
U.S.Amps makes the FAILURE TO OBSERVE THIS BASIC RULE WILL RESULT IN A SENSELESS WASTE OF POWER AND  
PERFORMANCE, and could damage your amplifier.  
Limited Warranty:  
U.S.Amps warrants all manufactured electronic products to be free from defects in material and workmanship for a  
period not to exceed TWO YEARS from the date of purchase.  
IMPORTANT WARRANTY NOTICE: U.S.Amps will only warrant and service products  
displaying valid U.S.Amps serial numbers. WARRANTY SERVICE WILL ONLY BE  
PERFORMED WHEN THE UNIT IS ACCOMPANIED BY A COPY OF THE ORIGINAL SALES  
RECEIPT FROM AN AUTHORIZED DEALER. All product returned to U.S.Amps for service  
MUST be accompanied by a Return Authorization Number, issued by U.S.Amps in  
advance of shipment. The Return Authorization Number must be clearly and conspicu-  
ously displayed on the shipping carton or U.S.Amps will refuse delivery.  
For Return Authorization Numbers, first call your U.S.Amps dealer you purchased the products from. The dealer will  
help you to obtain Return Authorization Numbers.  
This warranty extends only to the original purchaser and is not transferable. Defective equipment must be returned  
within the warranty period, freight prepaid, to the U.S.Amps Factory or an Authorized U.S.Amps Warranty Station.  
This warranty covers only detects in materials and workmanship of manufactured electronic products(amplifiers).  
Incidents of misuse, abuse, neglect, or unauthorized modification will not be covered within the terms of this  
warranty.  
U.S.Amps reserves the right to refuse warranty service under such conditions.  
U.S.AMPS WILL NOT BE RESPONSIBLE FOR ANY DAMAGES, WHETHER INCIDENTAL OR  
CONSEQUENTIAL, RELATED TO THE USE OF THIS OR ANY OTHER PRODUCT BEARING OR  
SOLD UNDER THE U.S.AMPS BRAND NAME. USE THIS PRODUCT AT YOUR OWN RISK.  
IMPROPER USE OF THIS PRODUCT CAN RESULT IN PROPERTY DAMAGE, BODILY HARM,  
AND OR OTHER DAMAGE. U.S.AMPS ASSUMES NO RESPONSIBILITY FOR YOUR HEALTH  
OR SAFETY.  

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