Introduction: Car Amplifier and Subwoofer Powered by a Computer Power Supply

Background Information:

For starters, your car amplifier is meant to receive its voltage from a 12 volt DC source which is your car battery. Common households use approximately 120 volts AC. So you can see that we two problems. The first is that we need 12v and not 120v, if this was the only problem it wouldn't too hard to solve. However the real problem is that we need DC electricity instead of AC. So why not use a simple transformer, like a cheap laptop charger that supplies 12v DC?

The problem with using some type of transformer is not that it puts out 12v but its the amperage. A typical car amplifier requires anywhere from 10-30 amps. (You can check how much amperage you need by looking at the fuses usually located close to the inputs on your amplifier.) So if you were to use a simple transformer that delivered 12v DV, it would most likely work at very low volume but it would get destroyed by the power needs once the volume starts to get louder and the amplifier requires more amperage. So, do they make transfers at a high amperage at 12v DC?

Yes, but they are often very expensive, easily on the upwards of a few hundred bucks for a quality one. So what's the best solution thats also more economical?

The best solution is to convert a computer power supply (CPS) to work at 12v DC and deliver high amounts of amperage. This is the most effective and possibly also the simplest way to get your amplifier working at full capacity. The process isn't too complex, it would be beneficial to have some knowledge of basic electronics and circuitry, and also be able to solder.


To begin, first know how many amps your amplifier needs. Do this by looking online or checking the fuses on your amp. Ideally you would want to exceed the amperage on the fuse so that your not constantly working the CPS too hard. This is the one i used, its rated at 24 amps for the 12v output. ( Once you have your CPS, search the serial number with additional words such as pinout to locate your models pinout sheet. Its typically not too hard to find pinouts of a CPS. Once located, you want to find the pin that says something like "PS_ON" or "PS_OK", typically located on the "Main Power Connector" plug. Most of the time the wire will be green but I have seen a few that have been purple or other different colors (typically older power supplies don't use green). Once you've located that wire, connect it to any of the black ground wires. What this does is allows the CPS to turn on properly. So once you've connected these two wires, try to turn on your CPSband it should work.

Now that you have your CPS working, unplug it and take the cover off. The orange wires usually supply 3.3v (good for wiring any LEDs if you want) and the red wires usually supply the 5v source, both in DC voltage of course. If your only using the CPS to power your amplifier, then trim all the orange and red wires. KEEP the Yellow and Black wires, those are the ones used to supply the voltage and ground the amplifier. Once down, group all the yellow and black together separately. I used zip ties so they weren't a mess.

I STRESS that it is needed to wire all the yellow wires and all the black wires to the amplifier. When running this high of voltage, just one or a few wires going to the amp may work great at first but it will lead to problems. Think about the wire thats used to connect the amplifier to your car battery, those wires are thick. Its not only a strong fire hazard but also keeps the voltage flow more open and puts less stress on the amplifier by wiring them all together.

Now you need to find a way to attach a bundle of wires to a small terminal on your amp. The best solution i found was to use a fork wire terminal for two reasons. (1) it makes a great connection. (2) it doesn't look sloppy. You can buy these at your local hardware store, automotive store and just about anywhere that has a hardware section. I would encourage you to solder the wires together into a bundle before crimping to terminal on. This ensures that every wire is connected and makes it hard to pull the wires out from the terminal. For extra precaution i heat shrinked the connection as well.

Additionally, you will want to bridge a wire from the 12v source on your amp to the "REM" or "REMOTE" terminal on your amplifier as well. This bridge allows the amplifier to turn on.
So connect the 12v, ground and REM wires to your amp and it should be good to turn on. Don't connect it to your subwoofer right away though.

Lastly, im sure you know how to connect your amplifier to your subwoofer but you need to know how to connect it to your stereo. This is a little complicated because of the amount of ohms your amplifier receives and the amount of ohms your stereo puts out. It almost all cases, your home stereo receiver will put out a 8ohm signal and your amplifier will require a 4ohm signal. This problemcan be easily solved by using the speaker level inputs on your car amplifier. Simply connect both channels of the speaker level inputs on your amplifier to just one pair of terminals on the back of your receiver. This splits one 8ohm signal into two even 4ohm signals for your amplifier. Double check your ohm ratings to be sure though.

Now, give it a try.

Additional Information:

Be careful, electronics can be fragile in the right environment and you don't want to damage something and spend hours or maybe days trouble shooting or having to re-buy something. There's no shame in posting a comment if your unclear about something and need help.

I have had offers to build the CPS unit already converted and ready to hook up. I have no problem doing this for a bit extra than what it costs for materials and shipping. Send me an email to work something out.


Snelo (author)2017-10-09

oh I forgot to mention that my amp is 4000w monoblock running two 1400w pioneer,, and another CPS running a pioneer carrozzeria double din with 4 mids connected to it, the reason I need to connect this capacitor thing is that I want to be able to switch on/off my monoblock using car stereo remote so I have to connect them all together on CPS

Snelo (author)2017-10-09

hi guys since I'm new here. i like this method n I've been using it since 2014. since some receivers do not have deep bass which is my favourite like 32 hz.,my question is can I connect a capacitor since my monoblock is too big (car capacitor to my CPS)

JakeR94 (author)2017-09-25

To clear some thing up, you can group all the yellow and black cable together as they are all connected together inside the PSU on the common 12V rail, you are better off connecting the cables together as this means the current isn't just taken from one connection on the PCB inside the PSU it also should keep the voltage stable and stops the wires from becoming overloaded. Cars use thicker cable due to the high amount of current being drawn from the battery lower voltage appliances tend to draw more current then higher voltage ones, it also helps reduce voltdrop. Someone has said that CCA is what you want to look for on a car battery this is incorrect as Cold Cranking Amps are for when the car is cold and you try to start the engine its designed for a very short duration while keeping a voltage of 12V, the actual battery usage you need to look at is measure in Ah these are usually much smaller then the CCA and are the rating you can safety continuously draw from a car battery. Note for the writer its a great article but i wouldn't recommend soldering then crimping, solder is very soft and will become loose after a while your better off crimping stright on the copper.

ddvniek (author)2010-10-23

Hi. I have recently hooked up my Amplifier to a PCU. But I only used one black and one yellow wire of the PCU to power it. You said to connect all the yellow wires to each other and all the black wires to each other, and to use them that way. But when I asked if I must connect the yellow and black wires together (Like you did) on Yahoo Answers, people told me I will blow my amp and PCU if I did that. Why I don't know.... Can you please tell me if I will blow it or not.
My PCU supply's 14A on 12V+
It's a 450W
Please help

eh1080 (author)ddvniek2010-10-31

Thats a great question. After some additional research, it appears that the standard wire size for a computer power supply is 18awg. According to various sources, it seems that 16A would be the maximum for an 18awg wire.

However, there is a lot of information that skews this 16A rating. Each situation has their own variables that need to be considered specifically for that application.

Personally, i have had this set up for about two years now and use it daily. I've also built many more of these conversions and have never had or heard of any problems.

This question leads me to wonder why the power cable in your car for an additional amplifier is so huge (like 4-8awg). It just doesn't add up to me, why you would be able to use an 18awg wire in your house and then have to use something like a 4awg wire in your car.

Theres clearly something i'm missing here, ill keep doing some research in my down time and see if i can figure this out. (author)eh10802017-08-22

In a car, the power run is usually 10 feet or more. Over longer distances, you'd require a thicker wire to maintain good amp draw. That's also why you'll often see smaller gauge ground wires right next to the amp. The shorter the run, the smaller you can go with the wire. That applies to both the positive and negative, by the way. If you have one of the various cars with the battery in the trunk, and you're connecting your amp just a couple of feet away, you can safely use significantly smaller wire. There are some tables online that can help you with this, and they take into consideration your amp draw and the distance to tell you which gauge of wire is ideal.

ThomasT7 (author)eh10802015-04-24

Thicker conductor is necessary for higher current, whereas thicker insulation is necessary for higher voltage. A car battery only supplies 12 volts, but it can pour out an enormous 200 amps. The current from the outlets in your walls probably won't ever exceed 15 amps, since that's what most household circuit breakers are rated for. However, the 110 volts needs more rubber around the wire.

Wire gauge also changes for the length of the connection. If you're just running a short connection from a power supply directly to an amplifier on top of it, you can get away with a slightly lower gauge wire. However, when wired up in your car, the wire has to worm its way from the battery and through the chassis and into the trunk. This extra distance will benefit from a thicker gauge to keep the wire from heating up.

This is why jumper cables are made with such thick wire. 200 amps going across ten to twenty feet requires a lot of copper.

Tech Mark (author)ThomasT72016-01-13

A typical car battery puts out 500-600 amps. Look for the CCA Cold cranking amps...on the battery.

ddvniek (author)eh10802010-11-05

Hmmm.... Yeah you're right. Maybe the power cables in a car is so huge because the car's battery Amp's are way bigger than the 16A of a CPS. I've read that a normal car battery gives round about 30A out. Thus the cable's need to be bigger to carry that type of current. Otherwise the cables could over heat and short out. Imagine 30 Amps running through a 18awg wire in a car.

Tech Mark (author)ddvniek2016-01-13

A car battery typically puts out 500 to 600 amps. Read your battery look for its CCA (Cold cranking amps ) Amp power wires are so big because the distance from the battery to your amp, would overheat a smaller wire due to the resistance of the wire and the load ( your amp) being at a distance. The smaller length wires on a psu work because the distance has fews ohms of impendence.

starfleet (author)ddvniek2010-11-20

Actually I'll give you a big hint.. there is a diffrence between House/Home electronics and Car Electronics.. It's called the Alternator.

Basically car electronics are typically 'over engineered' because unlike house hold appliances which typically can be certain that they are going to get a constant supply of power that isn't surging all over the place a Car can't.. you can actually watch this on (older) Cars simply by watching the Battery meter if your alternator starts to flux, the volts being thrown out by your battery also begins to flux as well, not to mention that cars have FUEL in them and are on rubber tires and don't ground easily.. it's better to over engineer their requirments there then to go 'oh damned we just blew up the car'

as for the actual output on the White PSU 12V and it's output Has any one actually bothered sticking a multimeter on a SINGLE plug and seeing what it's throwing out? My Multimeters dead atm so I can't.

ThomasT7 (author)starfleet2015-04-24

An electrical component only draws the amps it needs as dictated by its impedance, and a car's rubber tires do not affect its ability to ground because it doesn't get electricity from the power grid. Its ground is its chassis, which is connected to the negative terminal of the battery.

Is your multimeter dead because you bridged a high amperage power source with it? Using the unfused side of a multimeter to short a circuit which could potentially deliver over 20 amps is a bad idea.

The potential for current spikes from the alternator is a good point, though.

DerekD1 (author)starfleet2014-08-09

Si mon carnalito I have four of the 12v yellows connected together reading 13.4

eh1080 (author)ddvniek2010-11-06

Yes thats correct that they can give out something around 30A.

However though, the amount of amps running through the cable will only be what is needed by the amplifier at that instant. Especially for a smaller amp that would only require something like 15 or 20A at max. The size of the wire required even for a small amplifier is still something like 4 or 5 times bigger in diameter.

It might be partly due to the fact that the wire is running a long distance and that there would be a small voltage drop due to inefficiency with a small wire. However the increase in size due to the voltage drop would not account for that big of an increase of size for a wire only like 10-15ft.

hazexmods (author)eh10802010-11-18

Thicker wire has less resistance. Less resistance menas better sound.

Tkdkid121389 (author)eh10802016-01-07

The length of the power wire used in a car is different

Ilikeaudio (author)eh10802015-05-06

Hey, a question, if u have two 25a fuses on a four channel sony xplod 500 watt xm-504z, would u have to get a power supply to equal both fuses or just one? I want to bridge a 10" 300 watt sub and connect two speakers, how much amperage would i need, equal one fuse or both?

Ilikeaudio (author)Ilikeaudio2015-05-06

Im looking at this psu, what do u think?

kyismaster (author)eh10802010-11-29

Maybe because theres no alternator being cranked by your car and sending direct current? not really sure, thats my take at it. I custom built my conversion with a nitrious switch, as a On / off switch, its pretty sweet. i would make my own instructable but the nitro switch isnt exactly easy to disassemble. and is almost permanently soldered together, but then again i think the switch could handle 120Amps.

CanadianV (author)ddvniek2017-03-26

It's perfectly fine, connecting all the black wires together and all the yellow wires together in 2 separate clumps would put them in a parallel configuration which leaves the voltage the same but increases the amp draw, this is done with batteries all the time...

ThomasT7 (author)ddvniek2015-04-24

The people at Yahoo probably thought you meant shorting all the yellow wires directly to the black wires without a resistive load in between, like your amplifier. This most certainly would blow the power supply, and probably throw a breaker somewhere in your house.

Alternatively, you could buy some thicker gauge wire, solder all the yellow wires to one at the source, then solder all the black wires to another similar thick-gauge wire, and run just those two from the power supply to the amplifier. You really don't want to just use two of the original wires from the power supply. Running too much amperage through a single, thin wire is a fire hazard. (author)2017-08-22

Just using 2 wires from the 8ohm output of the stereo won't drop the load to 4ohm. You'd need an appropriate resister to make that work. That said, the input of the amp won't create a situation where it's drawing more current so your stereo system won't care, and as you already know - it will work fine. A better solution however, would be to use preamp outputs of your stereo receiver, if they are available. Another thing you might consider doing is to connect a switch between the 12V leads and the remote signal jumper. That would allow you to power the subwoofer on and off without having to use the switch on the power supply. An even more elegant solution would be to use a simple $10 relay switch to enable 12V signal to the remote control of the AMP when the relay senses input signal from the receiver. Besides that, the video is great and very convenient. Thanks!

BAMF (author)2017-08-01

Hi I did the project before on a VOX pathfinder where I wired an outboard amp on it. I found this article afterwards, but thank you so much nonetheless.

Some caveats I came across. First, switching power supplies are noisy buggers. I had to use some ferrite beads across the AC wires B+ wires and signal carrying wires. I also connected a 0.5 uf mylar capacitor (WVDC @50 volts should be plenty) to shunt out the high frequency noise across B+ and ground. Now it's as noisy as just about any normal guitar amp.

Suhail NajmiS (author)2017-06-07

I have PSU from a workstation CPU. It comes with 8-pin EPS12V but with 2 white/blue wire and 3 white wire. Its all rated at 12v. Should i bundled these 5 wires to the 12v yellow wire as well?

DawnM55 (author)2015-12-12

Just sell your car stuff already and by some respectable home av gear. Car audio stuff is dirty noisy has poor sonic accuracy and this is a super inefficient way to makes some noise. Multiple switching supplies, lots of drops, lot's of heat, and you would need a 1000 watt psu to get enough current at 12v to be useful to properly run a modest 100watt 2 channel amp.

Tech Mark (author)DawnM552016-01-13

I beg to differ with you. Car stereo equipment can surpass the sonic clarity of home systems...lower total harmonic distortion. And a 100 amp cps is enouh to power a 1000 watt amp. Watts/ volts= amps. So a 1000 watt amp needs 83..33 amps of power.

CanadianV (author)Tech Mark2017-03-26

Yeap, especially in smaller area's, most loud systems are designed for large areas whereas car equipment is designed for smaller spaces, if you want good quality sound in a bedroom/office or any other smaller space car audio can sound as good as the high end stuff.

Urmsd (author)2017-03-11

Ok quick question. Why do you need that bit at the end? If you have a pre out on your receiver at home (rca outs) why wouldn't you simply run them from receiver to amp and have amp run the sub itself? Since the amp will only send 2/4 ohm anyway. It just needs a signal from receiver or head unit from the car/ home audio receiver.

ProDigit80 made it! (author)2017-02-19

Just checking out the 'made it' feat.

ProDigit80 made it! (author)2017-02-19

Just checking out the 'made it's feat.

ProDigit80 (author)2017-02-19

All you need is a 12V, 5Amp power supply, and pair it with a 16V, 1Farad capacitor on the output.
The cap may be bulkier than the power adapter.
The power supply can be gotten from $15 on, the cap for $36 on, to 50, if you can find a 3 to 5 Farad.
If your car radio is reliable, you could try plugging it into 14.4-15V. the increase in voltage helps churn out a few more decibels.

StephenS264 made it! (author)2017-02-05

Hi, Just thought I would say thanks for the tutorial. We used a HP xw8200 600w PSU to run a 350w PA my daughter was using for her dance performances. I previously had converted a Behringer keyboard amp to 12v battery power so it could be more mobile for use in the park etc. The original amp was cactus so I used a bridgeable car amp I scored from Cash Converters for $20 to run it. The only issue we had with the PSU was with one of the sensor wires which needed to be earthed otherwise we only got 11.3v out of it. Once we figured that out we were getting 12.4v stable so it was all cool. In the pic you can see we use an Anderson high current coupling to join to the speaker that way I can interchange with the car battery when there is no 240v available. It works really well and I love it, what with the re purposing and everything. The amplifier has a bit of a hum in it which is doubled up cos of the bridging but once its cranked up you can't hear it and it's not supposed to be HiFi so I'm good with it. Thanks again.


chasterMTNskiier (author)2016-12-25

Hello I recently got 2 10in subwoofers each running at 700 watts RMS…I have THIS: amplifier going with them so I have a lot of wiggle room if needed…problem is though I'm trying not to spend about 75 dollars on this project only including the needed power supplies…on the amp itself there are 2 30 amp fuses which I will not be fully utilizing: I have been looking at buying 2 of these supplies: and trying to do it like that the problem is I don't know if that is enough please help me out :)


The subwoofers if you need to know are SoundStream Reference Series R.10 and I have 2 of them

YounesM7 (author)2016-10-15

Yo, still trending these days, i really want to know i only got 6 yellow wires and like twice the quantity in black wires, should i do all black with. 6 yellows? Or 6 yellows and 6 blacks?!

mananbhola003 (author)2016-10-05

Please help me out which wires to put in the +12v power supply

RossO12 (author)2016-08-23

Hey. Iv used this method to power my amp and sub with a psu that has a max wattage if 400. It eventually died as it was old and sqwealed from the start. I have now got another psu with a max wattage off 285.
The amp lights up and the psu powers up but there is no sound from the speakers!!!!

I only used a singal wire this time, is this the problem or is the psu too low wattage ?

LeviC21 (author)RossO122016-08-31

oh yehhh that PSU is wayyyyy to little power

SherifE14 (author)2016-08-25

Hi all, i'd like to use 2 PSU's to power one car amp. Any technical issues to look out for ? Will it work efficiently with no problems ?

LeviC21 (author)SherifE142016-08-31

yes, You better have a corsair 1200i to power that u may need even more power. Depends on how much current ur app need. just look at the fuses. if u have 30A fuses then u need a PSU of 360W or more (12V x 30A = 360W), so if you have 2 of those amps you need 720W or more PSU. simple math, Ritght?

GreggH11 (author)2016-08-18

Hi all. I would like to build a project like this that's full range. Maybe a pair of 5" coax and an 8" mid-woofer. I assume I could still do this using a 4-ch amp with two wired together for the sub? If I did something like 4x50 watts at 4ohms, could I get by with a 30-40A psu?

ChristianH104 (author)2016-07-07

Why does my power supply shut off after a couple of seconds after plug in. Only when hooked up to amp? No speakers or rca hooked up yet.

SethP12 (author)2016-03-04

I've been looking at plate amplifiers for my home subs that I'm splicing from 2 receivers into one unit. However the subs will require 300 watts which is expensive impedance will be 6 ohms, and one channel. Could I use a car amp with a psu, or do I have more options? The subs are small, but they hit very hard.

DouglasDHolt (author)2016-02-18

Overall, you've got most of the basics down regarding getting this
to work, but I think you need to learn some fundamental electronics. Especially
in regard to basic concepts. (Hey, I was new to this not that long ago, so I can sympathize.)

Voltage does not "flow". Current flows. A device does not "put out" a certain amount of ohms. The ohm rating is simply the impedance (resistance) of a particular circuit. You can't say things like "your amplifier will require a 4ohm signal". That's not how it works.

Sorry, not trying to be overly pedantic, but a lot of this information is misleading or just wrong. Still, I guess it gets you over the finish line, which is the point.

Fragantbump (author)2016-01-30

I got a 250 watt house subwoofer with built in amp i want to put in my car wat size power converter would i need and would it mess anything up

Ma2016 made it! (author)2016-01-30

Stress tested for 6 months it shakes my apartment after 3 hours of loud music its barely warm i love it added bluetooth for easy music playing love it.

Ma2016 (author)2016-01-30

Im using a x box 360 power supply its 175 w max 12v 14.2amp to power boss 1100 w monoblock amp pushes a polk audio 12 in sealed enclosure its been 6 months i stress tested it using it fairly high daily no over heating or issues at this time

DaytonD (author)2016-01-17

Im buying a 1000 watt amp how big of a psu do I need?

amdzackZ (author)DaytonD2016-01-27

1200w single rail will provide 100amp,should be enough

ChrisR161 (author)2016-01-17

QUESTION: reference the back of your receiver. Okay, I'm having a hard time to word this, BUT, okay, so the back of your receiver I see where you plugged in your speaker wire for the amplifier. Do you also have speaker wire coming from those same terminals to goto a normal speaker aswell? That's what it looks like, I wish the angle was a little bit more clear. You see I also run normal speakers off those terminals. Do you understand my questions?

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