ATX Powered Car Stereo, and 3 Way Speakers (for Home Use)




It's been a while since I've been researching about how to power up a car stereo without a 12 volt battery that I will surely have to recharge later. Why?
well....because I have a sony mp3 cd usb aux ipod-cable unit, 4x52w watts w/sub-out, what else could you ask for? I know, a nice set of speakers, right? I'm lucky to say that these speakers will be based on one set of sony 4 ohms 4 way drivers, another set of Boston acoustics 4 ohms 3 way, and one Miller&Kreisel 8" sub. Besides the custom speakers building, I will perform the foam repair job to the sub and to one pair of Boston drivers, i'm working on a tight budget so... here we go.

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Step 1: Stuff You Need

The second step is to gather the tools and items needed just to begin, it is not necessary to have everything at hand when you work on a project in the way I do, I only spent some of my free time, and I buy the things I need, this way I stay busy for a long. Yet there is nothing wrong with doing your project in one weekend but it can be frustrating and stressfull. Besides the fact that, when I start to do something I don't know exactly the way it will end, but the big idea is there, so I knew that my unit would ended mounted on a computer tower with a pair of "preview" speakers. So to start the tower, speakers and the atx power source are required the same as the drivers and stereo.

Step 2: Testing the Unit

Before we begin we must test that our stereo works properly when connected to the power source, here you'll find at least a couple of good INSTRUCTABLES on how to modify your power source to use it without the PC, the one I followed is "Convert-an-ATX-Power-Supply-Into-a-Regular-DC-Powe.pdf" This explains the key points to make this work, the most important thing is to link the green wire with any black wire, this way the source turns on automatically when plugged, and the other important thing is to sort all the wires by color, the important ones are: yellow 12 volts, red 5 volts, orange 3.3 volts and black is common ground, once this is done connect the unit's red and yellow wires( the yellow one is the cable that is energized at all times, and the red is the one that is energized at the accessory position of the ignition switch) , it is necessary that both wires are connected or else it won't turn on.

Step 3: Modify the Tower

So once we know that our unit is operating correctly, proceed to make modifications to the tower, always use your imagination, do not expect someone to tell you exactly how to do things, that alone will make you more numb.
Think, think and think again because once you cut it, it will be there forever, sadly I do not have a dremmell if I would've had one than the design might have been somewhat better, I used a saw and I struggled lot's to make the cuts, even so they weren't that bad.

I decided to install the unit in the center where the floppy should be, the top will be to keep things, is the size of a cd case, and the bottom will be my ipod station, control, usb and whatever may fit in.

Step 4: Mounting the Unit

Mount the stereo and start to make this look good, for it I use a thick cardboard that is used to create the background of some furniture, is easy to cut and sand, re-use your imagination and do it the way you want, for the top part I cut 5 pieces of cardboard to make a cube and glue it with plain glue, though they weren't near perfect size they were hold by pressure which facilitated the process of bonding. at the bottom I didn't use the same technique that was to have space for the ipod cable so I use one piece folded into 3 parts and screw it, I think this was the most difficult part, on top it I put a door using velcro you can do magic with it.

Step 5: "Preview" Speakers Installation and Basic Soldering and Wiring

Begins to extend the wires from the unit by soldering an extension, preferably using red and black colors wires to the speakers. Choose the proper place to install the speakers, use your imagination, they can be on the sides, top, front, bottom? however, the place where you decide to put them must have some holes to allow sound to flow a little better, remember that these speakers are not for a party, but are very useful when listening not loud music . I did the drilling of a similar size to those already in the tower, also added a double switch which allows me to use the speaker outputs with a worthy set of speakers, the switch of the image was replaced by another bigger with screws, the wiring is very basic switch has six poles one pair for input, and two pairs for output, ground wires (- black) must be linked together in pairs.

Step 6: Add the Extras

basically we have everything, just need to add the antenna, subwoofer outputs and spring clips, I will not add binding posts because they are more expensive and power is not that much. I tried to put an internal antenna, but it didn't worked there was no signal, so I add a car antenna, this way radio was enjoyable, the process is easy just plug the antenna to the stereo make a hole in the tower where you want to screw the antenna. For the subwoofer preamp output I bought a pair of rca to mount on a plate and mounted them on a piece of cardboard, make sure the rca don't not touch the tower or it will cause interference problems. Finally, for the spring clips use your imagination again, I mounted them on a piece of cardboard as shown in the images and adjusted it by pressure on the tower and finally with the Elmer's glue stix all, remember to weld all the pieces once you're sure about their position and operation. it would also be nice to add some extra support for the unit, and i forgot to mention that I added an array of leds that came out of a lamp they don't appear around here since this was a last moment modification lightning looks cool from the inside of the tower.

Step 7: Painting

Painting rocks, is my favorite part, no need to add lots of tape, just remove the unit and clean the tower, and start painting, color is a sweet black metallic, add a pair of extra layers to the cardboard.

Step 8: 4 Way Speakers

Be practical, I built this enclosure because I had already done a similar one before, the entire box is made of mdf, except the parts of the sides for this I use a thick cardboard some nail substitute glue which is very strong and flexible, the port is made of a sink tube, the pair of spring clips are very inexpensive and do not buy polyfill use pillow polyfill instead, the chrome bolts are there for appearance but it definitely has lot's of wood screws. Great sound, great treble and middle and good bass. obviously have to use a spring clip for each driver. finally sand, prime and paint...

Step 9: Boston 3 Way Speakers

I'm not going to write step by step how I did the speakers, because the Instructable How to Build Custom Speakers by noahw is just so sweet, so complete, that if you didn't got the idea with it, then you'll never will, but again I will say, use your imagination and be practical, I bought the BA735 speakers for $5 approximately, repaired speakers came in a truck that my brother had bought the front of the speaker box was from an old pair of speakers, the port is the same as the BA735, the I bought the crossover 50% off $6 The hole you see in almost perfect shape blue were made by a drill, the subwoofer is independent from the tweeter and midrange driver, follow the speaker repairing Instructable and make sure you're driver sounds near perfect.
Excellent crisp highs and really great mids and lows, the only problem is that both drivers are just to much for the unit, the volume needs to be really high and distortion levels seem to affect the drivers specially the sub else than that everything is perfect.

I'll let the pictures do the talking..

Step 10: Finally...

This was a good project to work with, the Miiler&Kreisel sub that i mention at the intro 8" 50 watts i pay $4 for it and it only needed the foam replacement( payed $2 for foam), also have one klipsch center channel that cost me the same. I see so many instructables that work on a heavy budget, or destroy expensive stuff to create cheap stuff. This sub will power up my new little system, and belive me it is deep bass for such a little guy. Any quiestion i'll be more than happy to answer.

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    42 Discussions


    5 years ago on Introduction

    I like your idea of reusing the tower case to house the head unit as well as keeping the fan as the head unit does get quite warm (be sure to remove the cover from the head unit to increase air flow). In my shop I would like to use an ATX to power my audio as well, right now I have a mechless Clairion head unit powered by a car battery/solar trickle charger pushing a surround sound set of speakers and a sub. The only problem I'm running into is the "Yellow" wire you mentioned in the beginning, that's for supply to memory for clock, audio settings and channel memory. How do I maintain 12vdc on that circuit when the head unit and the ATX are powered down? It would be nice if inside the head units circuitry the ground circuit was separate from the main power circuit then a set of CR32 batteries could be installed on the yellow wire. Any suggestions???

    1 reply

    Reply 4 years ago

    I know this is an old comment but I feel an easy way to supply a constant source would be to wire in a small 12 volt battery from a motorcycle or lawn mower. If your using this computer case design there should be plenty of room. I do not know if you would need to wire a charge circuit or if the 12 volt line off the atx psu would charge the battery on its own. Essentially the battery would act like a giant capacitor that will hold the radio's saved settings.


    4 years ago on Introduction

    Nice job! :) I am almost there too, but at the moment I have PSU connected to car stereo. And there is an issue already. Through the speakers there is loud noise - audio volume doesn't affect it. Noise is there when I play music from my laptop using 3.5 audio cable And laptop is connected to the mains for charging.

    I think that's what's called ground loop noise. And people suggest buying ground loop isolators for audio cables (typically RCA). Or one can build it with two 600 Ohms transformers with 1:1 ratio.
    But! People also say that it reduces audio quality. Which I would like to avoid if I can.

    I also read somewhere that using two ping laptop charger (in UK it's three pins for eeeeverything) would eliminate noise as well.. sound not right.. I want my laptop safe I guess..

    SO. I wonder could I break my ground loop where I connect PSU to Car Stereo (12v and ground)?

    Any suggestions?


    8 years ago on Introduction

    this helped me alot. thnx man. it was a little bit hard to follow, but i managed. since i dont have a car, i had the stereo and i put it in my old comp case. heres some pics. its not finished yet, im going to add a cover, lights, some plexi glass, and probably a few fans and usb ports. oh, and ill add a switch when i get the chance.

    4 replies

    Reply 8 years ago on Introduction

    Look's really nice, you managed to do a pretty clean job, I think the difficult part has already been done and there's no instructable for what's left. I'm glad it helped you ;-)


    Reply 8 years ago on Introduction

    i just have one question (so far, lol), does your power unit shutdown if you crank up the stereo too high with too much bass and loudness? i just found out mine will do that if i turn up the volume too high. im assuming the stereo is requesting too much power from the atx unit and there is a sensor that shuts it off. help


    Reply 8 years ago on Introduction

    Yes, your psu shutdown to protect itself from burning out, I used a 350 or 400 watts psu I don't exactly remember, and it never happened to me, but i recommend you use at least a 400 watts psu to ensure estability, or use more efficient speakers so that you get more db with less power. But i think it's cheaper and better to get a new psu. Sorry for answering so late.....


    9 years ago on Introduction

    why doesnt anyone on here use pro audio and seperates to run speakers?  in any case scenario i have put my crown amp purchased online for under 300 up against anything and a couple adapters to run it but it out does anything i try.  a car stereo sounds good because it is using your trunk and car to help reproduce sound.  it is powered by a battery because it has to be because it is in your car.  it is in no way better for in home use then something made for a home.  why would you go through the trouble of doing all of this when the outcome will no matter what be worse then if you do it right? 

    1 reply

    Well, i guess I'll have to check a couple of your instructables to get an idea on how to "do it right". Thanks for your comment....


    9 years ago on Introduction

     id use a normal home amplifier doing it this way complicates things and lowers sound quality. makes things much easier and can be done for the same price

    A simple power supply could be a car battery charger. I got a 10amp battery charger running my new car radio in my room and it works perfectly fine. Also running a 250w amp of it with two 10" mtx subwoofers.

    5 replies

    im sure it sounds horrible or may even be damaging your 250watt amp. First off ampsXvolts equals watts. therefore a assumed 250watt amp would need approximately about 20 watts just to push the amp at its max rated 250watts. plus a radio which generally can need about 20 amps of power nrigning your total to 40 amps at 12 volts. these are approximate numbers. so you dont even have enough power to push just the radio much less a highly overheating 250watt amp at its minimum.

    first off i hope you know that a 250 Watt amp is the max, only about 25-50 Watt RMS per not using the amp and radio. and i know the math because im in a bit of electronic classes this year and last year. it starts to distort at about 8-9 amps, which is about 96-108 Watts which is already above the RMS of my amp. all i was trying to state is that you could use a car battery charger as long as u got a smaller amp and you possibly do a little math. BUT yes i do under stand what your trying to say.

    PS: there is no sound difference(no distortion or anything).

    well actually only a badly made amp would rms at 25-50 watts when the stated power is 250watts. generally on a high quality amp like mtx audio, kicker, rf, etc. you looking at app. half of the total max wattage of the amp. the rms is generally the wattage at which the amp operates at optimum effeciency. so im assuming this amp is proably some boss audio or somthing that states 250watts when it has  10 amp fuse in it limitig it to a max of 120 watts. im not saying your wrong , your right, but in my opinion a power supply like a atx computer power supply of decent quality and about 500 watts would push a car audio amp of a reall 250 watts, that is if the 12volt rail has around 24 amps on it. and if it has dual 12volt volt rails at this amperage then you have a decent system in you bedroom.


    10 years ago on Step 6

    In regards to your internal antenna problem, you could try making a fractal antenna and put that on the inside. I made one(from an instructable) for my HDTV and it works great (mind you, it's not actually inside the tv). They use fractals in cellphones now. That's why you don't see antennas sticking out anymore. Just a thought. BTW i'm going to use your instructable at some point. I'm still accumulating parts. Thanks!

    1 reply

    i know its getto but all i did was stuck a 3.5mm headphone jack in the antenna spot with the headphones still attached and it made and awesome antenna, gets pretty good reception.