It might seem puzzling at first, but it’s actually not that hard to connect and power a car amp in your home.
In this detailed guide I’ll show you how along with detailed diagrams anyone can understand.
Here’s what you’ll learn:
- Car amp power supplies: what voltage & current ratings you need
- How to wire a computer power supply to an amp
- How to connect a car amp to a home stereo, smartphone or tablet, or Bluetooth
- Additional tips to make it easier & offer more options
- First facts: Can I use a car amplifier in my house?
- Choosing a power supply for car amp use
- DIAGRAM – How to wire a computer power supply to a car amp
- Remote wire options for turning the car amp on
- How to connect a home stereo, smartphone, or other audio sources to an amp
- What to do if you have ground loop noise (humming)
First facts: Can I use a car amplifier in my house?
Yes, it’s possible to use a car amplifier in your house. You can also connect a car amp to any home stereo, your smartphone, and more as an audio source.
There is a catch, though. Because car amps use a different power source than home stereos the biggest problem is getting them the power they need. Not only that, but they use a remote-on wire to turn the amp on & off to avoid draining a car battery – meaning that needs to be dealt with too.
Here’s a list of what we’ll need to cover:
- Signal inputs: Not all home stereos have RCA line-level jacks, so if you’d like to connect an amp to your home stereo it may require a workaround I’ll show you. You can also connect a car amp to nearly any smartphone or external Bluetooth receiver.
- Power source: Unlike home stereos powered by an alternating current (AC) electrical outlet, car amps work from a +12V direct current (DC) supply. You’ll need a +12V AC-DC power supply with enough current to run the amp. Not just any AC/DC 12V adapter will do – I’ll cover this below.
- Turning the amp on/off (remote wire): Home stereos or other audio devices don’t have a remote wire output to switch your amp on and off. However, there are some easy ways to deal with this, too.
You also need to know that:
- Unless you have all the parts already, you may need to spend a little bit of money to get what you need & get it working. The good news is that most of it is affordable and you can even make use of some power supplies like a computer DC supply you may left over.
- Retail stores are pretty bad about not having the parts you may need, so you might want to plan ahead and order parts online. You can find many affordably priced parts on Amazon, eBay, and from electronic part suppliers.
Choosing a power supply for car amp use
You can estimate how much electrical current (amperage, “amps”) your amp will draw based on its maximum power given in watts RMS. However, the truth is that’s only if you need a lot of power. For casual listening, you can get by with a lot less.
Basically, there are 2 ways to go about choosing a power supply for a car amp:
- Getting a “good enough” power supply if you’re not driving the amp hard (fine for casual listening)
- Estimating the amp’s current draw based on its power rating (useful for when you want serious amp power)
Of these, #1 makes it a lot simpler. You may be able to use a DC supply you’ve already got handy or a leftover computer power supply (sometimes called an ATX power supply).
What voltage does a car amp need?
Car amps normally work off of a range of voltages, not just 12 volts, although that’s used as a general reference. In fact, as a vehicle’s engine runs the alternator charges the battery and the voltage can range from near 12V to about 14.4V.
For home use, choose a power supply with a DC output from 12V to 13.8V, with 12V being perfectly fine to use. When shopping most of the higher-current supplies you’ll see are 12V anyhow.
At around 11V or so car amps and other car stereo equipment may shut off so it’s important to have enough voltage available.
What size power supply do I need?
Powering a car amp in your home requires a power supply with a decent amp rating. Standard wall adapters won’t work as they’re very weak (0.5 to 1A, usually). You can find bigger power supplies like a 5 amp model for under $15 if you shop smart. Desktop computer ATX power supplies are cheap, easy to find, and range in power ratings up to 500W or even more.
Option #1: Getting a “good enough” power supply for casual listening
When not driving an amp & speakers hard, I recommend at least a 2.5A supply for small amps (under 50W/channel). For 4 channels, I’d get a 5A or bigger. If you’d like to have more power, consider getting 15A or above.
You can find a 5A supply for under $15-$20 if you shop around. 10A and 15A supplies are fairly popular so they’re usually under $30-$35 dollars or so. When it comes to much bigger supplies that will let you drive a subwoofer with heavy bass things tend to get expensive. Very high current power supplies are around $100 and above for 30 amps or more.
However, one of the best options is to use a desktop computer power supply (“ATX” power supply) as they’re easy to find and have pretty good power output.
Option #2: Estimating amp current needed for higher power use
If you’re planning to use a car amp to drive speakers hard you’ll need a lot of amperage which you can estimate pretty closely We also need to take into account wasted power to come up with a final number. (All amps waste some power as heat and draw some additional current for that reason)
- Class D car amplifiers are more efficient and therefore waste less power (and draw less current) than standard class A/B amps.
- If you’re not sure what class your amp is, it’s probably class A/B. Class D amps normally say so on the amp itself, the box, or sales info. Class A/B types have been so popular for years that it’s a pretty safe assumption.
You can estimate amp current based on the maximum RMS power of the amp. Don’t use “peak” or “maximum” watt power ratings as these are misleading. We need to use the continuous power (RMS) the amp really delivers.
As class D car amps are around 85% efficient and A/B amps are around 65% or so efficient we can use that to estimate the total current an amp would need.
Estimate amps used by a 50W RMS x 4 amp:
- 4 x 50W = 200W total. (200W/12V) = 16.7A.
- Take into account power waste: 16.7A/.85 = 19.6A
Estimate current used by a 150W RMS x 2 amp:
- 2 x 150W = 300W total. (300W/12V) = 25A.
- Take into account power waste: 25A/.65 = 38.4A
As you see, to run a car amp at full power you’ll need a pretty big power supply! However, most people don’t so it’s usually a lot less hassle (and less money) to use one of the other supplies I showed examples of.
DIAGRAM – How to wire a computer power supply to a car amp
Using an ATX (desktop computer) power supply for a car amp isn’t hard usually. It’s a matter of a few steps:
- Power connections: Cut several ground wires (black) and +12V wires (yellow) and strip them for about 3/8″ to 1/2″ bare wire. Twist them together tightly or use a crimp connector (ring terminal, spade terminal, etc) and connect to the amp’s power & ground terminals.
- Supply on control: PC supplies don’t automatically come on even if the side switch is on. Normally a motherboard uses a control signal to the “supply on” wire pin. As shown in the diagram above, you’ll need to jumper the wire by cutting it, stripping it, and either connecting to a ground wire permanently or you can use a toggle switch.
- Amp remote on wire: As there are several good options for this, I’ll cover this in more detail below.
Once you’ve connected the supply-on wire to a ground wire the power supply should start and your car amp should work. Note that in some cases, it is possible to have a problem.
Huge, high-power car amplifiers can sometimes have a short current “spike” they draw when first connected to power. In some cases, this can trip the self-protect mode in power supplies. If that happens you can try starting the supply first and then give the remote wire power after a moment.
It’s possible you may need a more robust power supply if that happens as well. This shouldn’t be an issue most of the time, though.
Remote wire options for turning the car amp on
A car amp’s remote-on input uses a low-current +12V signal that starts its internal power circuitry. There are several good ways to do this:
- Jumper the remote on terminal: When wiring the power and ground 12V connections, you can use a small jumper wire from the +12V terminal to the remote terminal so it’s on any time the amp has power. 18AWG or smaller wire is fine.
- Jumper wire + switch: Basically the same, but you can also use a simple inline switch on the remote wire to turn it on/off yourself.
- Home stereo use – RCA converter with remote lead: If you’re connecting an amp to speaker outputs you can use a line level converter with a built-in remote wire output. They’ll automatically turn the amp on or off with an input signal present.
If you’re using a toggle switch on the remote wire you can leave the AC/DC power supply plugged in. When the amp’s remote wire is off (disconnected) the amp will shut off and won’t drain power.
RCA adapters with remote wire output
Example of a line-level converter with a remote wire output feature. When the speaker level inputs have a signal and it creates a +12V remote on signal. When no signal is detected, the remote wire will go to zero volts and turn the amplifier off. Unlike a regular converter, these need +12V and ground connections to work.
How to connect a home stereo, smartphone, or other audio sources to an amp
What’s great is how many options you have for getting an audio signal to your amp’s inputs. In fact, nearly any analog (non-digital) jack can be used from almost any device. I’ll cover some of the main ones here:
- Smartphones, tablets, and laptops can be used either by their headphone jack or via Bluetooth (see below)
- Any home stereo receiver or amp can be used – even vintage ones!
How to connect a smartphone or other device to a car amp (diagram & options)
Be aware that headphone jacks can be a good or bad audio source depending on your particular device. Even though they’re usually not quite as good as RCA outputs/AUX output jacks, I’ve had pretty good experiences doing using this with brand name smartphones or tablets.
In fact, I use this method to test a car amp at home.
You also use an affordably-priced Bluetooth receiver for around $25 from places like Amazon. They offer a direct line output jack or RCA jacks for this very reason.
Be sure to get a decent brand as the generic/no-name brand models tend to have sound quality problems and can produce odd noises between music tracks playing on your phone, for example.
How to connect a car amp to a home stereo (diagram & options)
The way you connect your car amp depends on both your home stereo and your car amp’s features. You’ll end up with one of 3 situations:
- Home stereo with no RCA output jacks + car amp with speaker level inputs: It’s actually fairly common for home stereos and home theater receivers to have no full-range RCA audio-out jacks. In this case, if your car amp has speaker level inputs built-in these can be connected to an unused pair of speaker terminals or alongside speaker terminals in use. The amp’s speaker level inputs will scale down the speaker signal to a much lower signal the amp needs.
- Home stereo with no RCA output jacks + car amp with RCA jacks only: In this case, you’ll have no choice but to use a line level converter used for car audio. Just like in #1 above, these are connected just like speakers to speaker terminals alone or alongside connected speakers.
- Home stereo with full range RCA output jacks + car amp: This is the easiest way by far. Unfortunately, not that many home stereos have full-range RCA output jacks. Some only have subwoofer RCA output jacks which are bass-only outputs. Full-range RCA output jacks can be connected directly to the car amp’s RCA inputs, but subwoofer RCA jacks won’t work for full-range music since they only pass bass.
What is a line level (RCA) converter and how do they work?
Shown here are two examples of line level/RCA speaker level converters that work well for home receiver/amp to subwoofer use. Both take a higher voltage speaker level signal and drop it down to a low voltage suitable for the amp’s input section.
Line level converters (also called RCA speaker level adapters) are small adapters that reduce the higher-voltage signals from speaker outputs to a much lower voltage (“line level”) used by a car amp’s RCA jack inputs. They can be connected directly to a ratio, amp, or speaker and provide RCA jack connections.
They’re really useful because they make it possible to connect an amplifier to a signal source that you otherwise can’t.
What to do if you have ground loop noise (humming)
A ground loop isolator you can use to “break” (isolate, disconnect) an amp’s RCA ground connections from that of an audio source to eliminate the electrical path that causes ground loop noise.
Sadly, noise can be a BIG headache when it comes to car amps despite them being designed to prevent it. The same is true that home stereos, too: anything that carries a signal and has a ground connection can create a “ground loop” that gets picked up by the amp and then turned into a very annoying noise you easily hear.
What causes ground loop noise?
Ground loop noise happens when there’s a slightly different potential (a slight difference in voltage) between the ground connections in an amp, stereo, and other components. Despite everything you try, sometimes it’s nearly impossible to eliminate.
In that case, you can try a simple RCA cable ground loop isolator which often solves it. Note that you shouldn’t try to get the cheapest you find because they can negatively affect sound quality.
You can find a good one for $10-$25 or above depending on the brand and features.
Can I use a 12 V bitmain mining power supply (133 A) to power my 1500w rms car amp and then connect that to pre-out subwoofer on A/V receiver?
Thanks for answering.
Hi, yes as long as it’s a standard 12DC output it should work, although I wouldn’t expect to get 1,500W from the car amp. However, the 133A output rating is very good and should work pretty well.
What’s nice though is you typically need a lot less power for the same volume when using speakers in your home etc. Best regards.
Hi! I just tried this with an old 400w pc power supply. Cut all the yellows and put a spade connector on them and did the same for the black. When I plug the power supply in and power it on, it just hums and nothing happens to the amp, the fan inside the power supply doesn’t spin either. I’ve tried with the jumper from the remote with the same results. What am I missing?
Hi there. Perhaps it’s not switching on fully or there’s another issue. I would test it with a PC motherboard (if possible) or double check that the on-control wiring is correct. Sometimes they’re not identical to other ATX power supplies and it can be confusing.
Justi, many PC supplies require a load to be attached for them to power on.
Sometimes this may need to be on the 3.3V or 5v not the 12v lines so it can take a bit of fiddling to know which.
In the past we used to get around this by using a resistor – a cheap ceramic one would work and not get too hot.
Connect a few fans or something like that to the PSU so it detects a load.
Also what have you connected to the main 24 pin cable that would go to the PC motherboard? It has the pins that you need to ground to power the PSU.
Do have a search online of how to turn on a computer PSU and maybe search “no load” or similar as well to see that style of solution if yours needs it.
Great points, Mick. I honestly forgot to mention a few of the things you’ve mentioned. Sadly it can be a real hassle sometimes to get a power supply of this type going.
Thank you for your contribution. :)
Do you cover anywhere how to set up a 10.1inch double din car multimedia head (brand pyle PLINTBL10) on a 10 amp fuse, to a set of component 6.5 mid bass speakers and .5″ tweeters each speaker and tweeter uses two way passive crossovers (brand pyle plg6c) , tweeters are 50 watts rms/100 watts peak, freq response 1.3-22khz, impedance 4 ohms. 6.5″ speakers are 200 watts rms/400 watts peak. the amp I have is also a pyle Marine brand 4-channel 400 watt amp (plmra402) on a 20amp fuse. I’m going to be using this as a home boom box for my shop that will be built into a box or enclosure. I would like to use switches in the front of the box to power on the head unit and amp. I want to use an AC/DC converter that plugs into the wall and don’t know what size to use I’m guessing a 12v/30a? Please assist as I can’t find specific diagrams on this exact set up up anywhere. Thank you and God bless.
Hi Samuel. Have a look here in case it’s helpful: https://soundcertified.com/how-to-hook-up-car-stereo-to-ac-power/
I would probably not use less than a 30A if it will be used at moderate volume and at least 50A if you’ll have it cranked up pretty high when in use. One thing to bear in mind is that power supplies can trip when near their current output limit as they can falsely sense a short circuit condition, so the more amperage capability you have the better, generally speaking.
(This is especially true for cheap supplies as they can trip pretty easily and shut off.)
Also don’t forget you’ll lose memory to the head unit so you might want a small 12V battery of some type wired the head unit’s memory (“BATT”) wire via a diode to maintain it while not in use. You could also additionally add a small ~1A AC-DC 12V adapter to maintain it as well (connected by diode so the main supply can’t backfeed to it and damage it).
The memory wire to the head unit, from the main +12V connection, would need to have a diode also to avoid backfeeding to the +12V power side on the amplifiers when doing this.
Have a good day! Hope that helps.
EDIT: I’ll need to add a diagram or two and update the article above regarding maintaining a head unit’s memory. A few others have asked about related topics. If you need a diagram to clarify what I mean, let me know. :)
Thanks for the quick supply its much appreciated. A diagram would be very useful I tend to learn by seeing or following diagrams, I have all those years in the Navy to taco for that they have a book of diagrams for everything in the service lol. I kinda know what you’re talking about I’ve used diodes here and there when building electric guitars and some acoustic electric guitars. It would be greatly appreciated. This is kinda the build I’m following I like this guys clean work he does just so you have an idea of what I’m doing. He uses a power source that I know will under power my speakers so if like to use what I stated instead for power. https://youtu.be/Plk9ivq6Ack. Thanks Marty look forward to your advice.
Hi Sam. I went ahead and created an example diagram and updated the article I linked above. Also, as the type of project you’re working on has been done before, it may be helpful to check out some of the example projects being shared here: https://projectgallery.parts-express.com/
If you haven’t already bought the amplifiers I’d reconsider buying those as you could use more efficient class D amps. They don’t waste as much power as heat as class A/B amps, meaning you may be able to get by with a lower amperage supply, take up less space, and it would weigh less also. Best regards.
I have an 800 RMS Class D mono amp I would like to use at home. It seems Id need a 70amp supply is that right, and what would be your advice on sourcing one?
Hi, well you can get an approximate idea of the maximum current draw in the manufacturer specs or using the fuse(s) as a guideline. But basically, a class D amp with 800W RMS max (total) power @ 12V would be about (800W/.85)/12V = 78 amps. So 70A would be about right.
Really though it depends on how much power you’re planning on using. You can get by with a smaller supply if you won’t be using it at full power. You might try electronics surplus suppliers for a higher amperage supply as one reader mentioned he found one like that for a good price.
You legend, thanks for your help!
You’re welcome. Have a good weekend. :)
Hey Marty, I got kind of confused on how to figure out what power supply is needed… I get your equation you have up top, but what I’m not understanding is does the wattage on the power supply need to match the amp? I have two old sound systems I pulled from my old tuners and the one set has a blown 1200W Rockford Fosgate, so I plan on using the amp with 1 of the subs to give me more kick in my home surround sound system. Any tips would be greatly appreciated! Feel free to ask me any questions that would help you with advice
Hi James. The power supply’s wattage doesn’t necessarily need to match that of the amp unless you’re wanting to get the full power from an amp. Indoor use is a bit different and you may not need to use the full amp capacity. Also, for high power amps, it can be hard to find an AC-DC supply that has a high enough current rating (plus they can be expensive if they’re big!).
Log story short, it would make sense you’re not going to drive a subwoofer at home with 1,200W so the supply will likely end up being a reasonably sized one. For example, let’s say (just as an example) the amplifier is rated fro 400 RMS/continuous max.
A 400W amp would draw about 50A (class A/B amp). But realistically if you only need about 1/2 the amp power, you may be able to do well with a 25A amp rated 12V supply. I usually recommend getting one a little bit bigger in case they can be fickle near their rated output.
Hopefully that helps. Do you have a model number for the amp or a bit more info like that? It would help to know.
I’d like to use a Sony XM-N1004 1000w 4 channel amp to power either a 250w15″ 8 ohm or a 350w 12″ 4ohm with 190w 8 ohm mids and tweets (2 each w.crossover included). I found a hive 750S power supply for cheap.
Is this doable?
The mids and tweets are actually 4 ohm
Hi Chris you can do that. I see that the 750S is rated for 62.5A so it should be capable of providing enough for the 70W / 85W x 4 from the amp.
(Note: you’ll get 1/2 the rated power available if using an 8Ω speaker instead of 4Ω). Best regards.
I got a dell 1000w power supply with the xk480 wiring harness on my main pin p1 all my yellow wires have a white strip down them are theses the 12 + wire bc I don’t have no yellow wires on that p1 pin , but I got 5 yellow wires on the other pins in the harness , so are the one with the white strip 12+ also and should be added with the regular yellow wires? or leave them out with the other yellows or not ? and can u add your 5+ and 3.6 + wires with your yellows or not I looked everywhere for this dell wiring harness color diagram
Hi, generally yellow would be kept together as they’re normally the +12V supply outputs. It sounds like that yes the white striped yellow wires are the 12V but sometimes it’s best to check it with a test meter to be sure.
You can’t connect the 5V or 3.3V wiring with 12V as that would likely back feed to the power supply and likely damage it.
Hello Marty I want to buy a car amplifier but I want to use it in my room I have 1 pioneer subwoofer 1600w (500W nom) and 2 6×9 pioneer speakers. So I’m kinda confused about DC power supply, My question is, if I buy one of the mentioned amplifier below:
Pioneer GM-7002 ×2 channel
• The reted power @ 2 ohms – 95Wx2
• Rated power @ 4 ohms – 70×2
• Rated power @ 4 ohms bridged 190W×1
• Max wattage @ 4 ohms – 125W×2/500W×1( bridge)
And this amp
Pioneer GM- 7004 70mrs ×4 channel
• Max wattage@ 4 ohms : 125W×4/500w×2 (Bridge)
• Rated power@ 2 ohms – 70W×4
• Rated power @4 ohms – 190W×4
Should I buy DC 12V 15A or 12V 30A? Or which one will you recommend me to buy?
Hello there. Those are class A/B amps so knowing this can estimate the *maximum* current they’ll use at full power (some power is wasted as heat). I’ll assume you’re using 4 ohm speakers.
GM-7002: (140W/12V) = 11.7A. Adjusting for efficieny, that’s 11.7A/.65 = about 18A.
GM-7004: 280W would result in about 2x the other amplifier, or about 36A max.
So you could ideally use a 15A for the 2 channel amp and a 30A for the 4 channel. However, if you’re not going to use the full power for the GM-7004 you can probably get by at moderate volume/power with a 15 or 20A DC supply.
Thanks marty! But will GM-7002 amplifier be enough for 1600w subwoofer?
Hi, it’s not really a 1,600W subwoofer. That’s the misleading “peak” or “maximum” power rating. The RMS rating will be much lower which should be fine.
Great article, I wanted to run my setup by you please to make sure I have it right.
What I have:
MTX Thunder 9500 10″ Subwoofer
MTX Thunder 801D Amplifier
The amp is 400W RMS in 4ohm bridged, and Class D. Based on your formula, I would need a 40A power supply – is this correct?
As I am based in the UK, would this power supply work?
Or what should I be looking for in a computer power supply for that option to work as I assume a 400W PC power supply won’t cut it?
Hi, you left off the Ohms rating for the subwoofer. However, long story short, that power supply (assuming it’s decent quality) should allow you to get somewhere around 300W @ 12V from the 801D.
If you’re using it at moderate power output at the most that should work out ok. To get all of the power it’s rated for you’d need more for sure – more than twice that.
To make things easier I’m about to post a car amp DC supply amperage calculator to make things easy. It should be up in about 1-2 days. Best regards.
Would the 500W version work better?
Or there is this:
Without opening the sub enclosure I cannot be 100% sure but it is either Dual 4 Ohm but most likely just 4 Ohm.
I am a little lost on wiring. Would -V go to the GND on the amplifier?
Any recommendations on which on/off switch I could buy for the remote wire so it isn’t always drawing power?
Thanks for your help.
Hi you can easily check the speaker load (Ohms) that the amp sees by measuring resistance with a test meter or Ohmmeter at the speaker terminals.
Ideally the 50A power supply would be better if you can get that. Yes, “V-” is the negative, or “ground” power connection on those power supplies. In this case, the “earth” (ground) symbol is for the incoming AC power but is normally not mandatory.
You can use any inexpensive, low-current toggle switch or rocker switch, etc., to switch the remote wire on & off. However, if the power supply is left running it will burn a very small amount of power even if the amplifier is switched off, so it’s probably more practical to turn that off instead (unless you have a preference for switching the amp off instead).
You are the man! This worked a charm. I went for the 50A 500W power supply.
Now my only issue is the amp/sub went into my dedicated cinema room and the power supply has a very noisy fan. I can hear it during the quiet scenes. I may swap it for a slower fan but means opening up the case.
Thanks for the help Marty.
You’re welcome. Yeah, unfortunately, that’s an issue sometimes with those sometimes. I’ve heard a few people say similar, but I’m glad to hear you’re up and going now.