Pc power suply to power car amp?

[Redseven80]

Can a pc power surply power a car amp? I also have an electric car seat will it do both? (for a driver cab) thanks.

[IntruderAlert]

http://www.mameworld.net/massive/How-to/Amp_Install/amp_install.html

http://forum.arcadecontrols.com/index.php/topic,16330.0.html

[Redseven80]

Thanks.

[Crazy Cooter]

An electric car seat draws an incredible amount of current.  I probably wouldn't hook that up to a PC PS... unless I had one sitting out in the garage... which I probably do...

Basically, I'd expect it to cook out in a short time if it worked at all.  No way would I hook it up to the same one that ran the computer.

[BobA]

Since you are interested in powering a car amp and a car seat you might want to look at using a car battery and a automatic charger.   The battery can provide the huge number of amps you need for both the seat and the car amp.   Heavy guage wiring is a must to get proper performance.   A charger and battery is alot cheaper then a DC supply that can provide the power you need.

BobA

[arcadeboy0000]

I have done this twice already with great results. I was not too satisfied with the existing tutorials so I just created mine. Its a nice no solder solution.

http://www.virtualdynamics.net/arcade/poweramp.htm

Feel free to post any other questions...

[Redseven80]

An electric car seat draws an incredible amount of current.

[paigeoliver]

Also, all that car stuff is 12 volt, I am pretty sure PC power supplies put out most of their juice on the 5 volt ines.

Car battery and automatic charger makes a lot more sense.

Really not sure why you need to use a car amp anyway, why not just use a home amp. Heck, I don't even know why you would need an amp at all? Even a cheapo set of PC speakers with sub has a lot more potential sound then I would ever want coming out of a game.

[elvis]

PC power supplies are switching supplies that auto adjust load by need.  If you draw all your load from the 12V line, that's just fine and dandy.  Consider that all modern P4 motherboards use a secondary 12V power header for the extra 12V needed on these energy-sucking boards.  Likewise, IDE hard disks all run on 12V.

Car amps on PC power supplies work just fine.  I've been running my setup that way for over 12 months now without issues.

Common sense prevails here.  Every amplifier and power supply is different.  *READ* the max ampage draw on your amp, and max ampage load available from your power supply.   When it comes to electricity: don't guess.  Electricity humbles anyone who doesn't take proper precautions.

My amplifier (2 channel, 200W total "max" [ie: PMPO] ) draws a max of 5A, and my 200W AT PSU can handle a max load of 8A.  So I'm well within safety limits there.  I run my computer of a separate ATX power supply so as not to damage my PC (or overload the power supply and possibly start a fire).   That said, if you had a whopping big 500W quality PSU (enermax, or other reputable brand and not cheap Codegen or Sparkle crap) you could safely run a low-end system and a low-end amp like mine.  Still, with PSUs being relatively cheap, I'd err on the side of caution and always have two power supplies.

A car battery and trickle charger is (a) bloody heavy/huge and (b) means having a tub full of HCl in your cab.  That's not something I feel comfortable doing with kids around when the alternative of a computer PSU is plenty safe (from a tip-over/spill point of view).

http://benchmark.mameworld.net/cab1/computer.html

[paigeoliver]

If you have a cabinet that can tip over easily then I would think THAT would be a bigger saftey hazard than whatever might come out of the battery (which should be both inside the cabinet, at the bottom, and SECURED).

[Redseven80]

Ok the 12vdc amp is 300w
            sub 400w / 3 ohms what will that combination be in amps?

[richms]

Depends if its a sony 300 watts or a rockford fosgate 300 watts since all manafactureres fudge there figures one way or another.

Best to look at the fuse requirements for the supply to the amp.

Also the power figures for the actual subs are the only area where there is more BS then the amps power figures.

So long as the amp isnt distorting, the sub should be fine. If the sub starts to disrort its generally just it reaching the end of its travel and not likly to cause it to burn out quickly.

General rule, if the sound coming out of it is clean, then nothings being stressed.

[elvis]

Ok the 12vdc amp is 300w
            sub 400w / 3 ohms what will that combination be in amps?

As above, is this 300W "max" (PMPO - Peak Mean Power Output) or 300W RMS (Root Mean Square)

http://en.wikipedia.org/wiki/PMPO
http://en.wikipedia.org/wiki/Root_mean_square

My two speakers are 120W PMPO.  RMS values are probably around 20W at most.  For my 200W power supply, this sort of draw is peanuts.

As for your max ampage draw, that should be clearly labelled on the amplifier, if it has passed all of your local safety certifications.

[richms]

If only it was that simple.

The facts are, normal unclipped music material has a RMS:Peak ratio of about 10dB - slightly lower on stuff heavy in the bass, and more on vocals. Your amp needs to pass the peaks of the music undistorted, whereas the total power used from the powersupply is the average. The car amps have a DC-DC voltage step up in them which averages out the powerdraw nicely.

So, your 120w peak speakers, on normal music will be outputting about 12 watts RMS, quite loud as anyone that owns some mcintosh audio gear with wattmeters will tell you

Most sony and other mid to lo-fi stuff measure it with a single tone at 1kHz at medium distortion levels (0.5-1%), and the sine waves RMS is only 3dB less then the peak power they will get from the voltage in the amp, so they get another 7dB on that rating over what you will actually be pushing thru it with normal music material.

If your not entering bass sound offs, you wont be playing anything remotely like that, so your 300 watts becomes something closer to 30.

PMPO is BS'd furthur by measuring the instantanious power as the amp swings from its maximum positive voltage, to the maximum negative voltage, as fast as it can, something that you will never use when driving speakers with audio (Unless you want to blow up your tweeters)

however, as amps use the output devices in linear mode, they disappate heat - allow for 50% efficiancy generally, perhaps less in a car amp since it has a switchmode voltage step up to waste more energy, so your (30 by 2) 60 watts of audio is actually 120 watts in from the power supply, with about 60 watts of heat into your cabinet, crude maths, but likly close enough to get you there.

In addition, the 300 watt car amp is most likly measured at 14.8 volts, which is the maximum charging voltage you will see in a car when its either really cold or really hot (Cant remember which) - and you are only giving it 12 volts, so the power output will not be near what they claim.

Anyway, the PC PSU _should_ have overload protection, and overheat protection, so if the amp does start to suck the juice too much, the PSU should shut down, but no guarentes naturally.

Perhaps put a blade fuse inline to the amp thats one step below the max 12 output of the PSU?

[BobA]

I agree a properly protected PC supply (separate) can power a car amp if power draw is matched or protected properly but you guys are forgetting the other part of the question.  He also has an electric car seat for the driving cab.  This means motors as well as the car amp.

BobA

[Wade]

The whole idea of using a car amp in a game cab just seems a little ass-backwards to me.  Don't most PC power supplies only have a max of 1 or 2 amps on the 12V output?  My relatively low wattage sony car amp (I think it was about 60) had a 20 amp fuse in it.  That alone told me that it was likely too much for a PC power supply.

I tried it, and it works, but the power supply cuts off if I turn up the volume much.

Seems it would be far more appropriate to either hack a set of good PC speakers (I have some that I paid $30 for years ago, which sound much better and louder than the car audio setup I tried), or even using a standard 120V AC amp (even better results, I'm sure).

Wade

[btoddkelley]

I have a 400 ps in my upright cab that has been powering a 35 X 2 Alpine car amp for 4 years. It also powers the motherboard! (amd 2500). Alpine amps a class A operation (This does not means sound quality, it is how the ouptut circuits are put togather) which are more ineffecient than a class AB. Class AB is the most common in car amps.
     At normal volume levels (which I do not know why anyone would exceed in a cab!) you would need about 85-90db. Most car speakers have a sensitivity of  87-91db at 1watt\1meter. Translation: It is unlikely the amp will ever draw more than about 2 amps.
     If you were to push the car amop to maximum smoke (just under clipping of the outputs) It would then draw the maximum found by ohms law earlier in the thread. Maximum output on a cab would put you about 6 inches away from the speaker. Sound energy falls off at the square of the distance. (inverse square law). 2 speakers with 87db sensitivity 1W/1M would be putting out 93db. at maximum smoke they would be putting out  about 106 db. That is REALLY LOUD! 

Todd

[Redseven80]

Thanks guys for the valuable info, the reason I'm using a car amp is that I'm using it (single channel bridged) to drive the sub under the seat and PC speaker amp to power the regular speakers L&R channels.

I want this thing to thump, and I will also receive an ass massage at the same time.....

[richms]

Does the seat have the adjustments on the seat and just need power, or were they somewhere else on the car that they came out of and you are having to hook into the motors directly yourself?