Sort of a trick question, how do I connect my car amp in my house

[tommymilan311]

Okay, so I don't want to spend a fortune. I have about 1000 watts of speaker and amp that I have laying around my house doing nothing. I did a complete audio over haul on my Kia Optima and currently have my old door speakers connected to my receiver with a cruddy Home Theater sub that is just way too underwhelming. So, I'd like to connect my Subs that I have laying around, the problem is that it looks like I'll need over 80 amps at 12V. Power supplies like that don't come cheap. $100+. I'm trying to stay under $50. Now I can get a 30A power supply for about $20-25 and a Cap for about $25. I'd really like to avoid using an actual car battery in my living room, so that is an absolute no go, I'd rather do nothing.

Do any of you think that a 12V 30A power supply and a Cap would do the trick?

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[fly_marlin]

You'll need a power inverter. Keep in mind, their specs may also be inflated. I think your best bet would be do find a 4 ohm stable HT receiver - I'm guessing you can run your subs at 4 ohms?

 

[r0llinlacs 10+ year member]

Find a decent computer power supply, they're a lot cheaper than a standalone 12v power supply, but you'll have to do some work (possibly tying rails together and also jumping the power button wires to make it turn on) You're on the right track though... look at supplied amperage, not advertised wattage. Also ditch the cap, it only adds another load for the supply to power, and spend the extra money on a better PSU.

If you could go over $50, you could get a lot more power supply for your money. Just to give you a rough idea, I'm looking at one now that is 58amps for $70. You're about right on target, looking at about $100 if you want 80 amps.

But keep in mind if your amp draws 80 amps and you use a PSU with less amps, you will be stressing the power supply and the amp, and the sound and output will suffer drastically, especially if you push it to distortion.

But to answer your question, yes, it can be done. I have an old 38amp computer PSU that I've had for probably 10 years now, abused the **** out of it, powered **** near anything you can think of with it, and it's still going strong. I use it mainly as a 12v test power supply but I originally modded it to power an amp like you're doing. The amp was too big for the PSU so voltage drop was bad and there was a ton of distortion. If you draw too much, the PSU will go into over-current protect mode and shut itself off. Yes it can be done, but you will get the best results if you match the PSU to the amp's current draw.

 

[tommymilan311]

You'll need a power inverter. Keep in mind, their specs may also be inflated. I think your best bet would be do find a 4 ohm stable HT receiver - I'm guessing you can run your subs at 4 ohms?

Yes, I have a 4 ohm 500 watt JL, and a 4 ohm 500 watt Infinity. We had these in my girlfriends kia soul with 2 other Kenwoods (the Kenwoods say 200 watt RMS, we've been at 500 watts for about 6 months, guy we bought them from had em at 600 watts for like 2+ years) and she didn't like them because she could no longer see out of her back window.

 

[tommymilan311]

Find a decent computer power supply, they're a lot cheaper than a standalone 12v power supply, but you'll have to do some work (possibly tying rails together and also jumping the power button wires to make it turn on) You're on the right track though... look at supplied amperage, not advertised wattage. Also ditch the cap, it only adds another load for the supply to power, and spend the extra money on a better PSU.
If you could go over $50, you could get a lot more power supply for your money. Just to give you a rough idea, I'm looking at one now that is 58amps for $70. You're about right on target, looking at about $100 if you want 80 amps.

But keep in mind if your amp draws 80 amps and you use a PSU with less amps, you will be stressing the power supply and the amp, and the sound and output will suffer drastically, especially if you push it to distortion.

But to answer your question, yes, it can be done. I have an old 38amp computer PSU that I've had for probably 10 years now, abused the **** out of it, powered **** near anything you can think of with it, and it's still going strong. I use it mainly as a 12v test power supply but I originally modded it to power an amp like you're doing. The amp was too big for the PSU so voltage drop was bad and there was a ton of distortion. If you draw too much, the PSU will go into over-current protect mode and shut itself off. Yes it can be done, but you will get the best results if you match the PSU to the amp's current draw.

I have thought about going the Power supply path, but it confuses me. When I look at the specs (and I don't have the best power supplies, just whats laying around) and at 12+V it reads 16A. Now, will it pull more amps from other sources, such as the 5+V that gives off 15 Amps, and so on, or am I limited to the 16amps?

I also DO NOT distort my speakers. I hate it, I hate the sound, I'm super sensitive to that. I don't even let my girlfriend play music off her phone because it doesn't sound right. I build my Optima around SQL, probably should have went with some better subs (I got Alpine SWR 10"), but I did a full on overhaul of door speakers and everything because it just wasn't to my standard of quality. But, my home system does not even come close to comparison. Anyhow, I'll likely play each speaker to 300-500 watts to avoid any distortion from the speakers (Probably closer to 500 if I can).

 

[r0llinlacs 10+ year member]

I have thought about going the Power supply path, but it confuses me. When I look at the specs (and I don't have the best power supplies, just whats laying around) and at 12+V it reads 16A. Now, will it pull more amps from other sources, such as the 5+V that gives off 15 Amps, and so on, or am I limited to the 16amps?
I also DO NOT distort my speakers. I hate it, I hate the sound, I'm super sensitive to that. I don't even let my girlfriend play music off her phone because it doesn't sound right. I build my Optima around SQL, probably should have went with some better subs (I got Alpine SWR 10"), but I did a full on overhaul of door speakers and everything because it just wasn't to my standard of quality. But, my home system does not even come close to comparison. Anyhow, I'll likely play each speaker to 300-500 watts to avoid any distortion from the speakers (Probably closer to 500 if I can).

No you are stuck with whatever the 12v rail/rails can provide, the 5v and 3v rails are completely separate.

What I'm saying about distortion is if you go with a weak power supply, you will hardly get any volume before it starts distorting so it may not be worth it to go with a weak power supply. Try the one you found and see what you can get out of it.

 

[wew lad 5,000+ posts]

I wonder if you could find a cheap power supply used online or at a pawn shop. Seems like a cheaper way to get a quality product, kind of like oscilloscopes. sometimes you can find the really nice old oscopes for around $40.

 

[r0llinlacs 10+ year member]

I wonder if you could find a cheap power supply used online or at a pawn shop. Seems like a cheaper way to get a quality product, kind of like oscilloscopes. sometimes you can find the really nice old oscopes for around $40.

It's possible. I got my old PSU from a computer that was sitting on the curb. Took it just to see what parts were left and/or good and I found that power supply. Checked the amperage on it and decided to turn it into a test bench power supply since it had a decent 12v amperage rating. Had it for about 10 years now, still going strong.

 

[tommymilan311]

No you are stuck with whatever the 12v rail/rails can provide, the 5v and 3v rails are completely separate.
What I'm saying about distortion is if you go with a weak power supply, you will hardly get any volume before it starts distorting so it may not be worth it to go with a weak power supply. Try the one you found and see what you can get out of it.

Could I connect 2 parallel? I have 2 of the exact same power supplies laying around. IDK, At the pawn shops they have the cigarette lighter 12V power supplies. But those are only at 6 amp. Like mention one here, the hard part is finding the proper amperage. But going back, IDK how to fully calculate amps pulled from the alt. Math tells me I will need a whole lot, math also tells me that my car can't power my system yet I have no issues except when the bass "slams" I get a little interior light dimming, no headlight dimming, my fans for my amp don't even appear to slow.

I've considered the whole battery approach and maybe even getting a 12V 30a power supply to work as a low power alt to charge the battery, but IDK if that will actually work, but can't think or why it wouldn't. But now I'm back to having a battery in my living room and I'd like to avoid that. I'm just as a loss, I am going to keep an eye out for a power supply or a plate amps at some of the thrift shops for one on the low.

Thanks again for the help.

 

[r0llinlacs 10+ year member]

Could I connect 2 parallel? I have 2 of the exact same power supplies laying around. IDK, At the pawn shops they have the cigarette lighter 12V power supplies. But those are only at 6 amp. Like mention one here, the hard part is finding the proper amperage. But going back, IDK how to fully calculate amps pulled from the alt. Math tells me I will need a whole lot, math also tells me that my car can't power my system yet I have no issues except when the bass "slams" I get a little interior light dimming, no headlight dimming, my fans for my amp don't even appear to slow.
I've considered the whole battery approach and maybe even getting a 12V 30a power supply to work as a low power alt to charge the battery, but IDK if that will actually work, but can't think or why it wouldn't. But now I'm back to having a battery in my living room and I'd like to avoid that. I'm just as a loss, I am going to keep an eye out for a power supply or a plate amps at some of the thrift shops for one on the low.

Thanks again for the help.

You can connect two parallel but it will only draw juice from one so it's pointless and it could ruin the PSU's. How many amps is the fuse in the amp? If it doesn't have one, what amp is it?

A battery is the best approach, hook a battery charger to it but it might cause extra noise. A PSU will not charge a battery, if you connect a battery to a PSU, the battery backfeeds into the PSU and actually powers/turns on the PSU like an uninterruptible backup power supply (UPS).

 

[tommymilan311]

One other thing I have come across is using a server power supply. I have come across quite a few that are about $25 online. They are generally at 12V so I have read. Some of the cheaper ones it is hard to get the full specs. But anyhow, the cheaper ones are at about 1000W which is roughly 80Amps at 12V which will do the trick.

I have been advised that noise could be an issue (the PS that I'm looking at says is generates noise at 50-60 Hz so it most likely will definitely be a problem.) But I have also been advised that Caps are a good way to reduce noise. Now I'm left at the question, should I use conventional caps or an audio cap?