using pc psu for active car subwoofer ....

Hi all there are 2 questions here lol , the first is the super long winded version, the second section is the super simple version of the question, i must warn you i am no sparky i have only a very basic knowledge of low density electricity lol ...enough to not be electrocuted while modding my pc!!

VERSION ONE!! ----------------------------------------------------------

I wasnt sure where to put this , so i put it here, seemed the right place

Ok, i recently got a cheap car subwoofer from a freind, who lost his lisence lol, its 4ohms 12v and 300-900 watts ....
And the only ways i found out to power it was via a large car/van battery , and a computer psu

I saw a calculation whereby the person describing the equasion ...used a 300 watt amp as an example, so he did the sum to work out the amperage needed to run this subwoofer in his home on his surround system, if i remember correctly it went like this .....300watts devided by the voltage number ...ie = 12, = 25 amps

But i was unsure if wattage of the actual PSU means anything? because i never really looked into amperage before , so i dont know the relationship, also ohms...im not sure how the ohm rating effects all of this, any how...what i know thus far is....i need 75 amps.....and many psu'c have the same amps no matter what wattage...

Also one thing i thought of, lets say i used a duel rail PSU, the amps of the entire thing....if it has 2 rails will that effectivly double the amperage? so then i could "double wire" the altered molex's into the subwoofers screw in power connectors? because its 2 seperate rails? but maybe the curcuitry is different ..in order , so maybe a duel rail psu only supplis a percentage of the amps to each rail?

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VERSION TWO!

How would i effectivly supply power to an active 300-900 watt amp - 4ohms - 12v?


Thank you for even reading this , looking forward to a reply or two

 

That's a novel way to re-purpose a piece of equipment! If you've already tried this at lower power and it worked, then you most likely are best off with a single railed Corsair 850W PSU which has 70A on the 12V. Spending $160 US for this is up to you. I'd just put a few more quid in and get a Logitech or similar speaker system.

 

Just an afterthought here about sound, you have to realize that car speakers are built for cars and the way they are built will not translate well into the home environment. You'll have to build something approximating a car boot.

 

hi all again thank you!!! thanks for the psu suggestion, i will have a look

ok just a little rant here

And about the afterthought, all this subwoofer needs is a corner for the port to fire into, exactly the same dynamics as any speaker / subwoofer, although as the bass reflex port is on one side, it would need to be placed on a "right hand side" corner so the actual unit / speaker drives forward, but as the port is firing into the corner it will have exactly the same if not better acoustic placement than in a car, for these units are only moderatly revised and changed to fit into cars, using the cars acoustic properties as around 50% of the sound, the actual speaker / driver are no different to a home subwoofer in physics, sound waves allways travel in an arc, it just depends how big the speaker is - relative to the size of the sound wave arc.....so in fact if placed correctly this sub will sound just as good as a "home theater" sub

ok back to non rant mode!

The ohms isnt very important...because standard floorstanders with a tweeter of some description are 4-8 ohm ..... 4 being the sub/mid 8 being the tweeter, and this sub runs at 4 ohms, also has a 50 - 1500 hz adjusting dial, a gain **volume** dial and a "bass boost" dial , here is a system that will r@pe any logitech all in 1 .......
1 x 300-900 w active sub running on its own channel in stereo because the input is stereo running at a standard flat 0db or maybe a little more but i keep it on flatline, because it just needs the signal and if i try to push power into the amp from a source it will obviosly destroy it, and a pair of tasty home floorstanders around 150rms , the bass turned down on the amplifier supplying the passive speakers so they play mainly treble and mid, the sub....well playing sub and volume adjusted to compliment not over ride the floorstanders, and there we have it


Im not trying to prove who knows what , you have 100% answered my question and i thank you for that , all i needed was the amperage.

I have sucessfully ran it on an old 17 amp 350 watt old old jeantech psu and it worked suprisingly well although using only just under 1 4th of the amps,. it topped out before it got to 40% ....but 40% was enough to annoy ppl so its all good, i dont want to annoy ppl i just want frequency

thank you

 

A UPS will make a good high amperage power supply and you can pick them up much cheaper than PSU's so they may be worth looking into but I think what you setup is fine and pretty cool.

Just a suggestion...

 

UPS uninteruptable power supply? ive never really looked at them...well mainly due to me not being a business lol and not having immediate work that needs saving if the power goes out, i thought they were expensive.... i will take a look

Thank you