title says everything....

11/5/2007 11:30:41 PM

just make sure the computer has a subwoofer output on it's onboard sound (or pci sound card)... typically black

and since computer sound cards are not pre-amped, you'll just need to convert the 3.5mm plug to the RCA plug and plug the computer output to your amp input (the external amp is needed to power your sub)

which means to not use it in a car, you'll need a 120v to 12v adapter to power your amp from a standard wall jack

this is all just a major guess

[Edited on November 5, 2007 at 11:43 PM. Reason : .]

11/5/2007 11:41:44 PM

mmm.. that will work but wont give you the grunt you need.

get a car batery and have a trickle down charger charging the battery all the time.
then just run your audio stuff off the batery directly, and get your inputs from the computer.

i am assuming a few things you didnt mention in your post...
1. you have a sub as in a 10' or 12'' or what ever, but a car speaker.
2. you are gonna use a car amp to drive it.
3. you know enough about basic electronics not to turn the battery into a welding machine for 10 seconds.(dont want you getting hurt now.)

11/6/2007 7:11:08 AM

It's pretty easy to pick up a $10 400w computer power supply and run a car amp on the 12v rail(yellow wires)...

11/6/2007 7:40:16 AM

mmm... i wouldent do that. infact i dont even know if that would work.


because batteries are pure DC, the look like this : _____________
computer power supplies take AC that looks like this : -_-_-_-_-_-_-_
and just mask out a phase and it ends up looking like this : _ _ _ _ _ _ _ _

i dont exactly know what that does to the components, dont think it would harm it, but i dont think it will have the umph to get it going.

and besided, new power supplies have to be connect to the mothe board to give any output, well not really, buty you will have to jump 2 very specific wires and if you dont know alot about electronics i wouldent advise doing that.




/////////////////////////////


i quickly hooked just my head unit up to a computer power supply, when i turn it on the light blinks and then it just turns off, i thought that it wouldnt have sufficient power. i cant speak for amps though. i just think that if you want the something that can handle some grunt go with the battery. id you wanna lay down some dollar you can get a RV power converter. but i wouldent.

[Edited on November 6, 2007 at 8:32 AM. Reason : tested the head unit with pc power suply.]

11/6/2007 8:23:02 AM

if you guys convince this kid to have a car battery next to his PC at all times...





i'll laugh.

11/6/2007 8:29:44 AM

"if you guys convince this kid to have a car battery next to his PC at all times...
i'll laugh."

you don't really have to have it next to the PC you know, i have one in my attic and just ran some copper to it. you wouldn't believe it but that stuff still conducts if you cant see the power source. amazing..

i laugh at your one dimensional way of thinking.

11/6/2007 8:35:24 AM

how long have you been running that setup?


it's laughable that you'd take that kind of risk. keeping a hydrogen leaking acid bucket in your attic sounds like a great plan....



~anyways


This will cost you about $3-400 to do.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817714001

Grab that. (12v line running 20 amps)



http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply
http://www.techpowerup.com/articles/other/22

do that.




it'll work.


It'll bump like all hell, too. strap your stapler to the desk.

[Edited on November 6, 2007 at 8:48 AM. Reason : ^ im sure your homeowners insurance /landlord would love to hear about that battery]

11/6/2007 8:44:57 AM

"it's laughable that you'd take that kind of risk"

you think keeping a battery in an attic is unsafe?
you think a battery can can leak enough hydrogen to cause poisoning/explosion?
seeing as how most (including mine) attics are vented and have good circulation of air.

i also check on the water once a month and the batery is in a batery box.

ps: you know that alarm systems have 12V batteries in the attic for if the power goes out, and i dont think insurance has a problem with that, in fact if i recall insurance goes down if you have alarm systems installed.

(as long as you dont short a car batery is it way safer(and potent) than almost any other power supply)

you still have a problem here: "single diode yielding a half wave (pulsating) output"

i know you can use pc power supplies as lab power supplies. i have one on my desk at all times, im just not sure what happenes when you try to power things that need a lot of power. power supplies these days will shot down so that they dont burn out, i imagine you can solve that but over riding that feature, but dont know how save that is.

"it'll work."

i just tried it on my head unit and it didnt. (im not saying its not possible, just think there are better solutions, non that involve tampering with the power supply, because you stand the chance of burning out alot of fuses or even breaking the power supply completely)

and it sure wont bump as hell, not enough POWER!!!!!!!!!

11/6/2007 9:22:32 AM

bwuahahahhahaahahaahahahaha.

dude, please... you fail to understand the concepts behind power supplies.

And the concept of input supply caps...

and the concept of voltage rail stability requirements in a PC...

what you tried, you didn't do properly, b/c I have done this countless times for long periods of time... and have designed many many many things that require VERY accurate DC supplies and were running on switched mode power circuits...

you connect the power button signal wire either high or low depending on it's active level... then you use as many yellow and black wires as there are available. the wire outputs are labeled on the top of most PC power supplies so it's pretty easy to find which wire is the turn on wire...

it works very well...


[Edited on November 6, 2007 at 11:31 AM. Reason : I speak from a wealth of experience and background... ]

11/6/2007 11:18:59 AM

i actually used a power supply to power my carPC when i was working on it inside the house to power my 12v dc-dc psu i had in my enclosure, so it does work

just make sure you get a PSU w/ a high amp rating as your amplifier may draw more than your PSU can handle...

11/6/2007 11:38:02 AM

which is the only reason i linked a 20A, $300 powersupply.


if you go small, you can save $texas

11/6/2007 11:43:35 AM

You can find $10-15 power supplies that will source 11amps on the 12v rail...(131wpeak) I have one... and I would imagine that you can find some for a little more that will source 15-20amps without paying $300...

Very important thing to note: DC Power = V*I. so 12v rail * 20a current = 240w(peak) source. the way these things work is that it's a fixed voltage, but current is drawn from a supply based on what load is presented to it. if the load asks for more current than it's capable of drawing I.e. it asks a 200w source for 25amps the voltage WILL be 8V as soon as the output buffer caps are deplete(pretty quickly) (which most amps will turn off ~10V so your amp would shut off)...

Car batteries are dirty, and if the power supply is properly wired then it should be safer than the car battery... however most people that are setting up things like this don't take the time to properly wire stuff b/c they are too eager to see it work, and then once it works it's working so why bother improving it for safeties sake...

I personally have an old industrial power supply that will source 45A @ 0-20v it works beautifully... and you can find them on ebay for ~$400 working or $50-100 broken... (mine was part of a lot I purchased)

and just in case anybody was wondering and wasn't clear... An amplifier is... an amplifier... the "Gain" is how much the input is multiplied by. So the power output = input signal*gain... how "loud" something is is the amplitude of the signal... softer points don't actually use all the wattage of the system... and you can set the gain to not max out the power supply... but it might or might not be as loud as you want it to be



[Edited on November 6, 2007 at 12:06 PM. Reason : PSU's can't really drive a car amp to full potential... but they do great for non extreme volumes]

11/6/2007 11:52:33 AM

^^yeah, but i don't think he needs 1100W, just make sure the peak power isn't over the computer PSU's peak, also the way computer PSU's are rated does not equal their output since their eff. is so low. so the higher efficiency PSU the better.

^what he said again


[Edited on November 6, 2007 at 11:57 AM. Reason : .]

11/6/2007 11:54:11 AM

Or you can buy those big ass capacitors and put that between the PSU and the amp that way you dont have to worry as much about overloading the amperage output of the PSU since you only need peak power a few times unless you blast it all the time(i would recomend doing this anyways since PSU's are built for a more constant output rather than the spikes you see in audio output.
Or rather than buying a $300 PSU and screwing around with it just buy a home stereo subwoofer/power supply for about the same price.

[Edited on November 6, 2007 at 12:44 PM. Reason : .]

11/6/2007 12:42:47 PM

the spikes shouldn't be a problem since most psu will have a 5% tolerance. so during the the spikes the voltage will drop to around 11.4 , any lower and it'll power off. newer cpus demand alot from the 12v rails and most psu these days have 2 12v rails that you can combine. i saw a psu at tiger driect the other day that was good for 36amps combined from the 12v rails... that's good for around a 400w amp. i've actually been running a 4 chan amp on my computer speakers for the last few months w. a small computer psu and it works great

11/6/2007 4:11:31 PM

http://www.circuitspecialists.com/prod.itml/icOid/8892

11/6/2007 4:35:36 PM