# Car audio amplifier vs rack mount - which fits my needs better?



## Wheres The Butta (Jun 6, 2009)

I am building a computer stereo (just two channel + sub)

I have a subwoofer plate amplifier already, now I just need a 2-channel amplifier to power my bookshelf speakers.

Since I am using spare car audio gear, the final impedence of the bookshelf speakers will be 4 ohms each.

My dilemma is this: Should I get a rack-mount amplifier that's powered by 120V AC, or should I find a high amperage DC power supply and run a car audio amplifier? 

I have a lanzar optidrive 500.2 that will put out PLENTY of power into 4 ohms, but it sucks a ton of power, so I would need a monstrous DC power supply. Something like 50+ amps.


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## Wheres The Butta (Jun 6, 2009)

OK, somebody just bought the lanzar amp. lol 

The question remains, but the car audio amplifier has changed - I have an assortment of them available, it really comes down to this:

Which will produce better sound quality: a car audio amplifier or a rack-mount amplifier?
Assuming they are comparable in terms of build quality and amount of power output.

Also, where would I find a nice DC power supply anyway?


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## Wheres The Butta (Jun 6, 2009)

If I choose to go with a lower powered amplifier, how about something like this?

SP-320-12, Mean Well SP-320-12

It should be fine for an amplifier that does 150wrmsx2 into 4 ohms right?


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## Wheres The Butta (Jun 6, 2009)

nobody has any experience with a DC power supply? 

I know I've seen people on this forum who use them... I just can't remember who lol


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## basshead (Sep 12, 2008)

Here's what I think:thinking:

If it's for home use I would get a good AC poweramp like the Bryston 4B.

Note: There's a lot less current conversion with the AC amp... AC>DC vs AC>DC>AC(@high frequency)>DC

If i had no choice but to go with a car amp i would run it from multiple batteries and only charge them when I don't listen to music.

This is what i would do, but what do i know...


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## goodstuff (Jan 9, 2008)

bd5034 said:


> nobody has any experience with a DC power supply?
> 
> I know I've seen people on this forum who use them... I just can't remember who lol


You can make one out of a comptuer power supply, but i don't know how much power you are looking for or how clean you want it.


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## Wheres The Butta (Jun 6, 2009)

well, I was going to run an amplifier that does 150wrms x 2 @ 4 ohms for a set of bookshelf speakers

if I can find a regular a/c amplifier that does 150wrms x 2 into 4 ohms for cheaper than the DC power supply, then I'll just use that.

The problem I'm finding is that any halfway respectable AC amplifier that can do 150x2 into 4 ohms is outrageously expensive. I don't feel like spending more than $200 shipped since it's just for a computer stereo. All the used ones I've seen that meet my criteria are banged up and ugly, or else they're about 20 years old and look like they're made in the stone age.


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## Cancerkazoo (Jul 21, 2006)

41Hz Audio:AMP15-PS Kit
$142.47
?



> This amp is designed for high voltages, up to +/-60V, with moderate output currents. It is best suited for relatively high impedance speakers like 8 or 16 ohms. It can be used for lower impedance loads like 4 ohms if the supply voltage is limited to around +/-35V.


 
miscellaneous.html

Avel-Lindberg Inc * Input: 2 X 120Vac 50-60Hz 3 1/4" Dia X 1 1/2" Tall


Output: 2 X 25V @ 2 Amps 100Va 

25 x 1.40400 = 35.1 volts


That would probably do it, and in keeping in the theme of the site, it's DIY


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## Wheres The Butta (Jun 6, 2009)

Cancerkazoo said:


> 41Hz Audio:AMP15-PS Kit
> $142.47
> ?
> 
> ...



35.1 volts? wouldn't I melt a car audio amplifier with that? Or will it be perfectly fine since the amperage is so insanely low? I'm going to need quite a few people backing this up to convince me it's safe before I try anything.


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## Cancerkazoo (Jul 21, 2006)

bd5034 said:


> 35.1 volts? wouldn't I melt a car audio amplifier with that? Or will it be perfectly fine since the amperage is so insanely low? I'm going to need quite a few people backing this up to convince me it's safe before I try anything.


yup, there is a +25v - 0v (reference) - 25v output on that transformer, I'm not sure of the price on it though. Originally I looked on partsexpress as they use to have a buyout e-core that was dual 25v out for $2-$3 but they must be sold out.

Also the 35.1 volts is after rectification so it matches perfectly with that amp, unless they meant 35v before rectification.

there is also a $39 100x2 Chinese amp people like HERE It need a PSU though and it sounds like a 36v industrial surplus SMPS seems to work well. (just needs +24-36v and ground, no center tapped transformer)


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## briansz (Feb 5, 2008)

I bought a pair of fan-cooled 45-amp PWM 12VDC supplies from a mainframe computer on Craig's List for $30 each awhile back. 

You don't see this stuff all the time on there but you can get good deals if you keep your eyes open.


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## Wheres The Butta (Jun 6, 2009)

I've got absolutely zero knowledge of electronics... I'm sure that I'd be able to put a kit together like that if I had somebody give me a little run-through, but I really would have no idea where to start on my own.


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## Cancerkazoo (Jul 21, 2006)

HERE is the thread for the sure electronics board. It would be the easiest for you. You just need the board @ $39.00 + a 24 - 36v PSU which can be had very cheap on ebay or industrial surplus sites. And since those amps are 80+% efficient you don't need a huge supply, some are running it off laptop PSUs.


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