Precision Power Stereo Amplifier PCX 250 User Manual

P C X 2 5 0  
P C X 2 8 0  
PrecisionPower 9235 South McKemy Street, Tempe, Arizona 85284 www.precisionpower.com  
8900-4005  
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NOTE: TOOLS ARE NOT SUPPLIED  
Small flat blade screwdriver  
Phillips screwdriver (#2 or medium sized)  
Wire cutters  
Wire strippers  
4 - #6 round head screws, and 1 - #8 sheet metal screw (or nut, bolt, flat washer  
star washer) [see detail]  
2 - Ring connectors (large enough to accommodate your method of grounding)  
In-line fuse or circuit breaker - see fuse chart below  
Power and ground wire - see Power Wire Calculator on page 4  
Speaker wire - 12 to 16 gauge  
Grommets (sized to work with the power wire you plan to use in your installation)  
Tube of silicone sealant  
You will need to install an in-line fuse or circuit breaker in the power wire  
within 18" of the battery. This fuse or circuit breaker is to protect your vehicle  
from fire in case the power wire shorts to the vehicle body. If you are only  
using one amplifier, use the fuse rating indicated in this chart. If you are using  
more than one amplifier, add up the fuse ratings for all the amplifiers. This sum is  
the rating for your main fuse or circuit breaker.You may also want to add a power  
distribution block near your amplifiers to distribute large gauge power cable to  
multiple amplifiers.  
Amplifier  
Maximum Fuse Rating  
PCX 250  
PCX 280  
30 Amp  
35 Amp  
18  
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Before beginning, disconnect the negative (-) terminal of the battery prior to  
working on the positive (+) terminal to prevent a short to ground. This is important,  
unless you want to spend the rest of your life with a nickname like "Sparky," or  
"Smokey." Reconnect the negative terminal only after all connections have been  
made.  
Warning! A Main Fuse must be installed within 18" of battery!  
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Once you have run both the power and ground wires, it's time to connect the  
cables to the amplifier. Cut off excess wire and, using wire strippers, strip the ends  
of the power and ground cables approximately 1/4 inch. Locate the PowerLock  
power and ground connector (supplied). With a small flat bladed screw driver,  
loosen the screws before attempting to insert the cables. Insert the wires into the  
appropriate hole, and tighten the screws. Check for stray strands of wire which  
may short out. Once the wires are secure, the PowerLock™ may be plugged into  
the amplifier. The Power/Ground PowerLock™ will accommodate 6 gauge wire  
for the PCX 250 and PCX 280.  
NO SOUND  
Is the LED lit?  
YES  
NO  
Check Power and Remote turn-on  
wire for voltage. Make sure Ground  
wire is secure.  
STILL NO SOUND  
See your Authorized PrecisionPower Dealer or call 1-800-62POWER.  
SOUND IN ONE CHANNEL ONLY  
Reverse left and right speakers by unplugging the speaker connector, turning it  
over and plugging it back in.  
Power/Ground PowerLock™  
SOUND IS NOW IN  
OPPOSITE CHANNEL  
SAME CHANNEL  
Reverse RCA inputs  
Problem is in the speaker or  
speaker wire of the silent channel  
SOUND IS NOW IN  
OPPOSITE CHANNEL  
SAME CHANNEL  
Reverse RCAs at head unit  
Problem is in the Amplifier. See your  
local Authorized PrecisionPower Dealer  
or call 1-800-62POWER.  
SOUND IS NOW IN  
OPPOSITE CHANNEL  
Problem is in the head unit  
or before the amplifier  
SAME CHANNEL  
Problem is in the RCAcables  
Short Circuit Protection engaged: The amplifier will turn off and try to come  
back on immediately. The amplifier will cycle like this indefinitely, with "blips" of  
sound each time. If this is the case, check your speakers and wiring for low  
impedance and short circuits.  
Thermal Protection engaged: The amplifier will turn off and several minutes  
later will come back on. In this case, ensure that there is nothing blocking the  
normal convective airflow of the amplifier. No obstruction should be within 2" of  
the amplifier on all sides.  
NOTE: Low battery voltage will cause the amplifier to run warmer and  
possibly damage the amplifier.  
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Your New! PCX™ amplifier has a TC-X Crossover (Total Control X-over ) 30-  
1. Cooling Plenums: Maintain a minimum 2” clearance around cooling plenums  
for proper amplifier cooling.  
2. Crossover HP/LP/FULL Select Switch: Adjust this switch to select the  
HPF/LPF/FULLfunction for the speaker outputs.  
3. Crossover Frequency Selector Control: Use this control to adjust the  
crossover frequency for the speaker output. (See Crossover frequency chart pg.19)  
4. RCA Inputs: Connect the RCA cables from source unit, or line driver to these  
RCAconnectors.  
4kHz (See page 19 for crossover Detent Chart). 12dB per octave phase correlat-  
ed crossover built in to provide superior system flexibility without the added  
expense and installation of an outboard crossover. The speaker outputs of  
your amplifier are high-pass, low-pass, or all-pass depending to the HP/LP/Full  
switch on the front endplate. You would choose low pass (switch middle) to use  
this amp for subwoofers, choose high pass (switch left), or full (switch right) to use  
this amp for full range speakers.  
5. Gain Control: Use this control to match the output level of the source-unit to  
the input of the amplifier.  
6. -12dB Input Attenuation: Push this switch ‘IN’ for high voltage input (4V-12V)  
capability. This button pushed ‘IN’ must be used for speaker level input on common  
ground head-units or for high voltage line drivers.  
The RCAoutputs are controlled by a separate HP/LP/Full switch, and are always  
independent of the speaker output crossover. As well as being able to independently  
select HP/LP/Full, your new PCX™ amplifier allows independent selection of  
frequencies from 30-4kHz (See page 19).  
NOTE: The System Diagrams beginning on page 15 show several ways to use  
the virtually unlimited PCX™ amplifiers internal crossovers in your system.  
PCX 250, 280 Control Panel  
1. Adjust all amplifier input gain controls to just above minimum sensitivity (fully  
counterclockwise).  
2. Using the cleanest music source (CD) playing, turn up the head unit source  
volume until you can hear distortion. Now turn it down a bit until you cannot hear  
the distortion (usually just below full volume).  
3. Increase the Amplifier gain (clockwise) until the onset of audible distortion.  
Then decrease the gain to the point just before the distortion starts. This setting  
minimizes background noise and prevents overload.  
4. Repeat step 3 for any remaining amplifiers in the system.  
7. QBASS™ Frequency Control: Buttons 1 and 2 offer the capability of selecting  
30, 36, 44, or 60Hz to boost by the QBASS™ Control. (See page #2)  
8. Output Crossover HP/LP/FULL Select Switch: Adjust this switch to select  
the HP/LP/FULL function for the RCAoutputs.  
9. Output Crossover Frequency Knob: Use this control to adjust the crossover  
frequency for the RCAoutput. (See Crossover frequency chart pg.19)  
10. RCA Outputs: Left and right RCA outputs provide HP/LP/Full; 30-4KHz to  
another amplifier.  
11. Speaker Output Connections: Plug the speaker PowerLock™ connector in  
here.  
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There are two sets of RCA jacks on the front end of your amplifier. The RCA  
cables from your source unit go in the set labeled INPUTS. If your source unit doesn't  
have RCA outputs don't worry. Simply add a set of RCA plugs (available at your  
dealer) to your front or rear set of speaker leads (see drawing below), plug them  
into the input jacks, and push to the IN the -12dB input attenuation switch.  
Run the speaker wires from the amplifier location through the vehicle to the  
speakers. Observe the same precautions for routing these wires that you followed  
for running the power and remote turn-on wires. Cut off excess and, using wire  
strippers, strip 1/4 inch of insulation. Locate the speaker/remote turn-on  
PowerLock connector. Loosen the outer screws on the underside of the connector.  
Insert the speaker leads into the end. Check to be sure you've maintained proper  
polarity before securing each wire, and plug the PowerLock into the amplifier.  
The Advanced Instrumentation Input has trickled down from the $15,000  
PrecisionPower2500F1. This circuit completely isolates the chassis ground from  
the audio circuit of the amplifier and reduces noise radiated into your signal cables  
by up to 40dB. This is equivalent to a noise reduction of approximately one hundred  
times what the noise level would be without this circuitry. It provides all the benefits  
of a true 'balanced' line without the need of any special cables (see diagram  
below). This type of input works with any conventional RCAcable.  
All two-channel PCXamplifiers are capable of being bridged into a 4 ohm mono  
output without switches or bridging modules. This feature permits the creation of  
a mono channel for a subwoofer or center channel. Deriving the mono channel  
is accomplished by using the Left Channel Positive wire (L+) as the positive speaker  
wire and the Right Channel Negative wire (R-) as the negative speaker wire.  
NOTE: It is important that a minimum 4 ohm impedance is observed. If the  
impedance drops below 4 ohms while the amplifier is wired in the bridged  
configuration, the amplifier's protection circuitry (AM-IV) may engage.  
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The New! PCX™ amplifiers mass has been increased by 2 lbs. per linear foot  
over last year’s POWERCLASS™ amplifiers, resulting in far superior heat  
dissipation. The unique heatsink on your PCXamplifier has been designed with  
fins on the inside of the aluminum extrusion. This allows for the transfer of heat  
from the circuitry to the heatsink fins and out through the vents in the endplates.  
Be sure you have ample space around the amplifier for cooling; at least 2" on all  
sides.  
PCX 250 Power Panel  
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1. Cooling Plenums: Maintain a minimum 2” clearance around cooling plenums  
for proper amplifier cooling.  
2. QBASS™ Control: Add more bass to the system by turning this control clock-  
wise to boost the selected QBASS™ frequency up to 18dB.  
To manage the additional heat associated with higher output capability, a thermally  
controlled fan has been designed into the PCX 280. When the heatsink temperature  
reaches a pre-determined value, the fan is activated and cool air is drawn in  
through the lower intake vents on the endplate. This cool air flows below the circuit  
board, through the fan and across the internal fins, cooling the heatsink. The  
warm air is then forced out through the upper endplate exhaust vents.  
3. QBASS™ Remote Port: Port to plug in the optional QBASS Plus™ Remote  
knob.  
4. Power & Ground Connections: After connecting the power and ground  
cables to the PowerLock™ wire connector, plug it in here.  
5. Power Indicator: A green light indicates that the amplifier power is ON.  
PCX 280 Power Panel  
1
4
3
2
5
8
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The ability to run stereo speakers while simultaneously running a mono output  
from the same amplifier is accomplished by running the stereo speakers normally  
and tapping into the appropriate wires for the "mixed mono" channel (left channel  
positive for the positive speaker wire and right channel negative for the negative  
speaker wire). Speaker impedance should be no lower than 2 Ohms on the stereo  
channels and 4 ohms on the mono channel.  
Locate an area near the amplifier(s) that is metal and clean an area about the size  
of a quarter to bare metal. Inspect the area around and underneath to be sure you  
won't drill into wires, brake or fuel lines, etc. Drill a pilot hole in the middle of this  
area. Terminate the ground wire with a ring connector and attach it to the bare  
metal using a #8 sheet metal screw and washer or preferably, a bolt, nut and a  
star washer (not supplied). We suggest crimping and soldering this connection.  
After the connection is complete, coat the area (on both sides) with silicone or  
some similar material to prevent rust from developing on the bare metal. If your  
grand total current draw is over 50 amps(or total output power is over 300 watts),  
you should run a separate ground wire beside your power wire from the battery  
to the amplifier(s). Keep the ground and power wires as close together as possi-  
ble, and use the same gauge wire for both. This will ensure that you have a good  
ground path, and may eliminate such potential problems as engine noise and  
overheated amplifiers.  
NOTE: Passive crossovers must be used for "mixed mono" operation. Choose a  
low pass crossover around 100Hz for your subwoofer, then choose a high pass  
crossover for your stereo channels. The high pass crossover must be at the same  
or slightly higher frequency than the low pass crossover to maintain the correct  
impedance. See your PrecisionPower dealer or call 1-800-62POWER for more  
information about passive crossovers.  
If your grand total current draw is over 100 amps (or total output power is over  
600 watts), you are probably exceeding the capability of your charging system.  
Dimming lights and fluctuating voltage are solid indicators that you need to  
upgrade your alternator, battery, or both. Keep in mind that your amplifiers simply  
convert electrical energy to acoustical energy, and any electrical deficiency will  
compromise the performance of your sound system. For more information about  
charging system upgrades, see your local authorized PrecisionPower Dealer or  
call PrecisionPower Technical Support at 1-800-62POWER x 229.  
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The following is a basic formula to be used as a guide to determine current draw.  
A50% amplifier efficiency rating is used as an average. Your new PCXamplifier  
is more efficient than most other amplifiers. This formula is to be used as a guideline.  
Using wire of a larger gauge can only improve the current transfer of your system.  
Do not use smaller gauge wire.  
Total Amplifier RMS output x 2 = Total Input Wattage from car  
Total Input Wattage = Current Draw (in Amps)  
Supply Voltage  
Example: A POWERCLASS™ PCX 280 amplifier has two channels at 80w per  
channel RMS rating into 4 Ohms (80 x 2 = 160).  
You would use the formula in the following way:  
160W x 2 = 320W  
320W = 26.6 Amps Total current draw.  
12V  
If the same amplifier is driven into a 2 Ohm stereo or 4 Ohm mono load, double  
it's 4 Ohm RMS rating. All POWERCLASS™ amplifiers will effectively double their  
power at this load.  
160W x 2 x 2 = 640W  
640W = 53.3 Amps Total current draw.  
12V  
If you are using more than one amplifier, add up the total current draw for all of  
them and choose the appropriate gauge based on the grand total.  
Recommended Minimum Gauge  
Total Current Draw  
Length Of Wire To Be Run  
(in amps) Up to 4ft. 4 to 7ft. 7 to 10ft. 10 to 13ft. 13 to 16ft. 16 to 19ft. 19 to 22ft. 22 to 28ft.  
25-50  
50-65  
10  
8
10  
8
8
6
8
4
6
4
6
4
4
4
4
2
65-85  
6
6
4
4
2
2
2
0
85-105  
105-125  
125-150  
150-200  
200-250  
6
4
2
0
6
4
2
0
4
4
2
0
2
2
2
0
2
2
0
00  
000  
2
0
0
00  
000  
2
0
0
00  
000  
0
0
00  
000  
0000  
00  
00  
00  
000  
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NOTE: The ground wire must be the same gauge or larger as the power wire.  
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QBASS™ (PCX 250)  
Up to 12dB of Boost centered at 40Hz, with a Q-Factor of 2.  
QBASS Plus™ (PCX 280)  
Up to 18dB of Boost with selectable center frequency at 30Hz, 36Hz, 44Hz or  
60Hz, with a Q-Factor of 2.  
Optional QBASS REMOTE™ (PCX 280)  
This boost control can be mounted in the dash and will supersede the boost con-  
trol on the amplifier endplate.  
Q BASS™ Settings  
1
IN  
IN  
2
IN  
Freq.  
30Hz  
OUT 36Hz  
44Hz  
OUT IN  
OUT OUT 60Hz  
Optional QBASS REMOTE™: This boost control can be mounted in the dash and  
will supersede the boost control on the endplate.  
PrecisionPowerPCX™ amplifiers no longer need an optional QPORTto connect  
multiple QBASS PLUS™ equipped amplifiers while using one QBASS  
REMOTE™. The new QBASS PLUS™ circuitry in the PCX™ amplifiers is now  
positioned before the crossover circuit. In doing this, PrecisionPower engineers  
have allowed you to daisy chain your RCAoutput to the next amplifier input, causing  
the first amplifier’s Q BASS Remote™ to become the master control amplifier. See  
your Authorized PrecisionPower Dealerfor more information! (See diagram pg.18)  
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Three-Year Limited U.S.A Warranty  
This warranty gives you specific legal rights, and you may also have other rights which vary from state  
to state. PrecisionPower warrants its products to be free from defects in materials and workmanship  
under normal use and service for a period of three (3) years from the date of original purchase when  
the unit is installed by an Authorized Dealer. Non-Authorized Dealer installed products carry a one (1)  
year parts and ninety (90) days labor limited warranty. The extent and conditions of Limited Warranty  
are as follows:  
And thank you for choosingPrecisionPower audio equipment. AtPrecisionPower  
we proudly design, engineer and manufacture audio products at our production  
facilities. Our award winning engineering team utilizes innovative technology to  
TM  
consistently deliver Absolutely State of the Art performance, sound quality,  
reliability, and value. This PrecisionPower product reflects our commitment to  
offer you unparalleled versatility and quality for years of dependable service and  
listening enjoyment.  
1. Authorized Dealer Installed Products: PrecisionPower will either repair or replace at no charge, to  
the original purchaser, any unit which PrecisionPower examination discloses to be defective and  
under warranty, provided the defect occurs within three (3) years from the date of original purchase  
when the unit is installed by an Authorized Dealer and the product is returned immediately to  
PrecisionPower. This warranty is not transferable.  
2. Non-Authorized Dealer Installed Products: PrecisionPower will either repair or replace at no charge,  
to the original purchaser, any unit which PrecisionPower examination discloses to be defective and  
under warranty, provided the defect occurs within ninety (90) days from the date of purchase and the  
product is returned immediately to PrecisionPower. Warranty claims beyond ninety (90) days for Non-  
Authorized Dealer Installed Products will be for parts only and will extend for one (1) year from the  
date of purchase. This warranty is not transferable.  
3. Internet and mail order products purchased from non authorized PrecisionPower dealers are not  
subject to factory warranty. PrecisionPower does not endorse or approve of internet and mail order  
sales, but will repair products at current non warrantied part and labor rates.  
4. The date of purchase and proof of Authorized Dealer Installation of aPrecisionPower product must  
be established by an original sales receipt which must accompany the article being re-turned for war-  
ranty work.  
5. This warranty shall NOTapply to any PrecisionPower product found to have the original factory serial  
number removed or defaced. All products received (by PrecisionPower) for in warranty or out of war-  
ranty repair, with their original serial numbers removed or defaced, will NOT be repaired and will be  
returned to sender, freight collect. Refer to original packaging for the serial number of your component  
speakers.  
6. The provisions of this warranty shall not apply to any PrecisionPower product used for a purpose  
for which it is not designed, which has been repaired or altered in any way, or which has been con-  
nected, installed, or adjusted other than in accordance with the instructions furnished in  
PrecisionPower owner’s manual. Nor shall this warranty apply to any part which has been subject to  
misuse, neglect, or accident.  
Do not attempt to service PrecisionPower products yourself. Performing  
exploratory surgery on your audio equipment yourself will void the warranty. Many  
parts of yourPrecisionPower product are custom built to our specifications. Our  
factory parts are not made available to anyone else nor are they for sale. Our goal  
is to make sure that your PrecisionPower product will always sound as good as  
the day it was purchased. Contact your Authorized PrecisionPower Dealer about  
obtaining any warranty service through PrecisionPower. (See Warranty inside  
back cover)  
7. PrecisionPower does not authorize any other persons to assume any other liability in connection  
with its products. THIS WARRANTY IS THE ONLY EXPRESS WARRANTY MADE BY  
PrecisionPower APPLICABLE TO ITS PRODUCTS. ANY IMPLIED WARRANTY OR MER-  
CHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE APPLICABLE TO PrecisionPower  
PRODUCTS IS LIMITED IN DURATION TO THE DURATION OF THIS LIMITED WARRANTY.  
PrecisionPower SHALL NOT BE LIABLE FOR THE INCIDENTAL, CONSEQUENTIAL, OR COM-  
MERCIAL DAMAGES RESULTING FROM THE BREACH OF THIS WRITTEN WARRANTY. Some  
states or provinces do not allow the exclusion or limitation of incidental or consequential damages or  
limitations on how long an implied warranty lasts;so the above limitations or exclusions may not apply  
to you.  
8. Your product will be serviced on an in-warranty basis within the warranty period for the correction  
of warranted defects. If improper operation of your PrecisionPower product should occur, contact your  
Authorized Dealer for assistance with the return and factory repair of your PrecisionPower product. If  
an Authorized Dealer is not available, return the unit including your name, telephone number, return  
address, a copy of your sales receipt, and a description of the problem to:  
The extended use of a high powered audio system may result in hearing loss or  
damage. While PrecisionPower systems are capable of "Concert Level" volumes  
with incredible accuracy, they are also designed for you to enjoy at more reasonable  
levels all of the sonic subtleties created by musicians. Please try to observe all  
local sound ordinances.  
PrecisionPower  
Service Department  
9235 S. McKemy Street  
Tempe, AZ 85284  
TO RETURN PrecisionPower PRODUCTS OUTOF WARRANTY: Return the unit, postage prepaid,  
in the original protective carton. Please include a description of the problem and, if desired, a request  
for an estimate of repair costs. Unless a request for an estimate is included, the unit will be repaired  
as necessary. Please contact PrecisionPower Customer Service at 1-800-62-POWER for questions  
concerning out of warranty repair charges. Repaired unit will be returned with an itemized statement,  
C.O.D.  
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