Author Topic: Running a car amplifier off mains / high current power supply help.  (Read 3023 times)

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Offline z.s.tar.gzTopic starter

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I have an amplifier that I'd like to hook up for some sweet bass. The amp works fine with a car battery supplying the power (its intended purpose) but I can't get enough current off a former-computer power supply to take care of the peaks. What would you recommend to remedy this? My initial thoughts are put some capacitors in but even then I may not be getting enough for a sustained sound.
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Offline want2learn

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Re: Running a car amplifier off mains / high current power supply help.
« Reply #1 on: February 04, 2011, 05:05:24 AM »
What's the amps rated power?

What's the power supply's rated power on the 12v line?

There's a couple of threads on rcgroups about parelelling pc power supplies but take care!!

Why do you want to run the car amp and not one intended for the mains supply?

Jim
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Offline garrettg84

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Re: Running a car amplifier off mains / high current power supply help.
« Reply #2 on: February 04, 2011, 07:24:17 AM »
Depending on the amp draw of the amp/subs you will likely need something more like a car battery(or two or three) with a charger always hooked up. I know I had a system that would draw hundreds of amps when the bass really hit. Had a capacitor bank and with the draw I still went through a couple of 200amp alternators a year.


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Offline want2learn

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Re: Running a car amplifier off mains / high current power supply help.
« Reply #3 on: February 04, 2011, 07:30:06 AM »
The power coming straight from most car battery chargers isn't regulated well enough.

Charging the battery(ies) overnight/when not in use would be a better solution.

Jim
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Offline z.s.tar.gzTopic starter

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Re: Running a car amplifier off mains / high current power supply help.
« Reply #4 on: February 04, 2011, 10:10:25 AM »
@want2learn
Lets say for all intents and purposes the amp is rated 100W peak and 50W rms.

The power supply is rated 8A but of course that's constant, not peak.

I could put a few in parallel but that means scrapping some perfectly good psu's.

I have no money for a proper one and already own a car amp.

@garretg84
My lack of money means I don't have a car battery lying around to use.

Believe me,  this system couldn't draw more than 15A if it tried.

That's why high schools were invented; punks have to be corralled somewhere. (I was no exception.)
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Offline Soeren

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Re: Running a car amplifier off mains / high current power supply help.
« Reply #5 on: February 04, 2011, 12:31:47 PM »
Hi,

If you add a large caps (10,000F to 1F depending on the peaks) and a couple of small ones (like 100F, 1F and 10nF) for noise, you should get it to handle the peaks just fine.
Remember to use heavy and short wires.
Regards,
Sren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
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Offline want2learn

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Re: Running a car amplifier off mains / high current power supply help.
« Reply #6 on: February 04, 2011, 04:11:08 PM »
Lets say for all intents and purposes the amp is rated 100W peak and 50W rms.

The power supply is rated 8A but of course that's constant, not peak.

In that case the maths is close enough, just don't run the amp at full whack all the time and remeber to allow adequate cooling of the amp and psu.

I have no money for a proper one and already own a car amp.

Thats fair enough, there's a lot of us in that boat!!!

Jim
The question that drives me hazy:

Am I, or the others crazy?

Offline z.s.tar.gzTopic starter

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Re: Running a car amplifier off mains / high current power supply help.
« Reply #7 on: February 04, 2011, 08:00:20 PM »
I can't run the amp at full power because my cheap speaker bottoms out so it's not a problem  :P
I'm also not worried about the amp overheating since it's rated for 600W and is a brick of aluminum but I may put some better heatsinks in the psu. (I honestly forgot about heat)

edit: I put a 10,000uF cap in and it helped by a noticeable amount. I can get about 10 more of these pretty cheap but my concern is this: if I put say 10 capacitors in parallel do they need balancing? I've read this and that but I can't dig up a definite answer.
« Last Edit: February 04, 2011, 08:28:30 PM by z.s.tar.gz »
Save yourself the typing. Just call me Zach.

Offline Soeren

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Re: Running a car amplifier off mains / high current power supply help.
« Reply #8 on: February 04, 2011, 09:24:08 PM »
Hi,

edit: I put a 10,000uF cap in and it helped by a noticeable amount. I can get about 10 more of these pretty cheap but my concern is this: if I put say 10 capacitors in parallel do they need balancing? I've read this and that but I can't dig up a definite answer.
Capacitors don't need any balancing (whatever you may have read), as long as they're connected together, they cannot be at different voltages, so they're self balancing you may say.

Add 1 or a few at a time, and keep an eye on the start up surge (and the punch in the low frequencies of course, no need to add more than needed to cure the lows).
A large capacitance looks like a short circuit to the power supply at start up - you may even need to add a soft start circuit.
Suitable PTC resistor(s) would do the trick. A power resistor that is shunted by a relay when the caps are up is another common solution.
Regards,
Sren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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