12v powersupply

Posted: Thu Jul 10, 2008 11:11 am

Greetings,

I'm thinking about using a car amplifier in my house.
It's a 12v 600w amp.
So I would need a 12v power supply that can handle a max of 50amps, just over 35amps rms. My mains are 240v 50hz.
I've thought about using car batteries, but that wouldn't be all that portable and can you just hook up the battery between a crap transformer and the amp and let the battery act like a huge capacitor? I'm not really sure if the potential difference put across the battery would be put across the transformer causing it to melt. I know how I can find out but mum hates it when I burn the paint.
Did I mention I'm pov? Do I need to, I'm trying to hook up a car amp in my (mums) house... That aside, I'm keen to get this sub working. And all I can find are $300 upwards... I don't have a budget, I also don't have $300.
Any ideas or suggestions are welcome.

Thanks.

Posted: Thu Jul 10, 2008 1:18 pm

2 questions -
Why
and
Why???

Posted: Thu Jul 10, 2008 1:29 pm

I thinking about a computer PSU with a single 12v rail at the required amperage. It's just that I don't know if the 3v and 5v lines can stay unused without damaging the PSU. It is much more compact than a set of car batteries.

Then again: why??

Posted: Fri Jul 11, 2008 12:43 am

Cucco wrote:

2 questions -
Why
and
Why???

Well, I'm not really sure, but I think it's because it's only a small step from scorching the wall before you burn the house down.

And...

A friend of mine just got a new car and has no where to put this enormous sub and amp. I'm keen to see if it makes the bass more punchy and loud.
Currently we use a Roland Keyboard amp for the bass guitar.
So, this should be an improvement. Razz

I haven't seen a 35amp nominal PSU for a computer... I will look about. Cheers.

Posted: Fri Jul 11, 2008 5:25 am

Greener wrote:

Greetings,

I'm thinking about using a car amplifier in my house.
It's a 12v 600w amp.
So I would need a 12v power supply that can handle a max of 50amps, just over 35amps rms. My mains are 240v 50hz.
I've thought about using car batteries, but that wouldn't be all that portable and can you just hook up the battery between a crap transformer and the amp and let the battery act like a huge capacitor? I'm not really sure if the potential difference put across the battery would be put across the transformer causing it to melt. I know how I can find out but mum hates it when I burn the paint.
Did I mention I'm pov? Do I need to, I'm trying to hook up a car amp in my (mums) house... That aside, I'm keen to get this sub working. And all I can find are $300 upwards... I don't have a budget, I also don't have $300.
Any ideas or suggestions are welcome.

Thanks.

A 600W rating for a car audio amp is not what people in sound engineering would call 600W - it's a marketing term.

Nevertheless, here's a link to a $120 12V 40A supply, which would be quite enough juice. The same unit is available from a number of different suppliers. Make sure your d.c. wires are good'n'thick.
http://www.mpja.com/prodinfo.asp?number=16751+PS

Posted: Fri Jul 11, 2008 6:03 am

Quote:

I'm keen to see if it makes the bass more punchy and loud.
Currently we use a Roland Keyboard amp for the bass guitar.
So, this should be an improvement. Razz

An improvement? I doubt it. Not worth the time, trouble or even $5 to do this, but after you do, please report back with what you've learned.

Kapt.Krunch Wink

Posted: Fri Jul 11, 2008 9:55 am

It's not the size of the amp, it's what you do with it.

Thanks Boswell. That's a definite front runner atm.
I have some fat as cables for the power, like as thick as your little finger. And some beefy speaker cable.

The Roland is cactus, going to use the line out on the back and this as the power amp and speaker.
I will test with a car battery before buying the PS.

Cheers.

Posted: Fri Jul 11, 2008 11:41 pm

Greener wrote:

Did I mention I'm pov?

No you didn't...but why would you?

Posted: Sat Jul 12, 2008 12:40 am

Mainly to discern that I was looking for the cheapest example of a power supply.

Quick Cats like yourself may have already figured it out.

Posted: Sat Jul 12, 2008 1:05 am

Quote:

I have some fat as cables for the power, like as thick as your little finger. And some beefy speaker cable.

I have some fat, as the grease dripping from under the bacon in the skillet.

Sadly, the wires in your wall aren't that thick, nor are they any thicker than 12 gauge 3 wire, if that, I'd imagine...

Laughing

Posted: Sat Jul 12, 2008 4:57 am

Greener wrote:

Greetings,

I'm thinking about using a car amplifier in my house.
It's a 12v 600w amp.
So I would need a 12v power supply that can handle a max of 50amps, just over 35amps rms. My mains are 240v 50hz.
I've thought about using car batteries, but that wouldn't be all that portable and can you just hook up the battery between a crap transformer and the amp and let the battery act like a huge capacitor? I'm not really sure if the potential difference put across the battery would be put across the transformer causing it to melt. I know how I can find out but mum hates it when I burn the paint.
Did I mention I'm pov? Do I need to, I'm trying to hook up a car amp in my (mums) house... That aside, I'm keen to get this sub working. And all I can find are $300 upwards... I don't have a budget, I also don't have $300.
Any ideas or suggestions are welcome.

Thanks.

Dynaudio made a pair of audio amps that ran off of batteries. There are hi fi golden ears who run their amplifiers off batteries saying that they can hear the difference when their stuff is connected to the wall and when it is running on batteries.

The amp, unless it is running in class A mode will not be drawing 35 amps all of the time only when it is called on to deliver maximum power.

The 40 amp power supply shown is a switching type power supply and may be great for things like computers but audio gear may not be too happy with it. Auto power amplifiers are use to a very pure source of DC coming from the battery and are not designed to have choppy DC coming from a switching power supply so you may have to put some giant caps across the supply to do some filtering.

Considering all the problems I honestly think you would be better with a conventional power line driven amplifier. YMMV

If you decide to run your amplifier off a battery then I would get a deep discharge marine battery as they are use to being drained and recharged multiple times and are very robust. The only problem is that they can cost double or triple what a conventional battery costs.

Best of luck!

Posted: Sat Jul 12, 2008 9:29 am

There is no problem doing what you want. You could use a switching supply or a conventional transformer based supply. Your home conventional amp isn't any different. You plug it into the wall, but the internal power supply converts the power to 5 or 12 volts DC to run the amp. Tube amps had a 6 volt supply for heater filaments, and 300 volts DC or more for the tubes. In electronics, nothihng actually runs at 120 or in your case, 240 AC.

Early switching supplies were a little noisy but I don't think that is a problem anymore. They are standard equipment with amateur radio operators who are very picky about their equipment. Unlike the golden ear hi fi goofs, they actualy have the test equipment to see what is going on at each stage of amplification.

8 or 10 gauge wire should be fine.

Posted: Sat Jul 12, 2008 1:04 pm

Soaking up the info guys, thanks heaps.

Putting together an idea atm, got a few various PSU's from computers laying about.

If I took 3 or 4 200w PSU's, put them parallel into one of these am I asking for a house fire?

Posted: Sat Jul 12, 2008 10:48 pm

So, this is for your control room?? You want a car stereo amplifier for your control? You must be quite a farmer? Mushroom farmer. I'll send you a power supply if you send me some of those magic mushrooms you've been eating. More power! Less filling! More power! Less filling! Your speakers are blown. Your speakers are blown. Your speakers are blown. And your record is stuck.

I'd like to record directly into my brain since that's where I will be listening to things.
Ms. Remy Ann David

Posted: Sat Jul 12, 2008 10:58 pm

Umm, not for the control room. For the Bass Playa!

Although, I'm going to have to borrow his bass and do some testing. I'm positive I can blow this thing up if I try. So our Bass Playa will blow it up without trying.

Know what I mean?

Btw, I don't have a control room. Just control.

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