# Why NOT use car audio amps as home audio amps?



## elvisjer (May 13, 2008)

Hey everyone! So I just got my 55amp cascade audio power supply unit that I'm currently using to power an older subwoofer amp i had lying around for my home audio system. I just picked up a pair of Infinity RS 2.5 vintage super hifi speakers that require a good solid 200-500w for thier potential. The watkins woofers on them drop to 2Ω sometimes and suck up tons of juice as opposed to the 4x EMIT ribbon tweets on each of them and need a good amp for them. Since most home audio amplifiers can't handle anything below 4Ω and put out anywhere near the power for these puppies I was just thinking what the DISADVANTAGE of getting another power supply and using one of my SS amps or something to power them. Is there a big SQ problem or something i'm overlooking?

Thanks!


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## Mooble (Oct 21, 2007)

No, no problems at all as long as you have a beefy power supply. I am thinking about using one of mine as a home amp since I don't think I could ever bring myself to sell it.


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## elvisjer (May 13, 2008)

So there's got to be some disadvantage to this right?! Why would people NOT do this more often? I guess lots of home theater stuff actually adds tone and stuff to the sound in the same way guitar amps do, are car audio amps just cold or something in that respect?


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## m3gunner (Aug 6, 2008)

It's not very efficient to convert 120 AC to 12 DC then have the power supply in the power amp convert back to whatever voltage your amp requires... there are losses at both conversions.

Way more efficient to just convert from 120 AC to whatever DC voltages you might need in a home amp.

Also... in past lives, car amps were way more expensive than a comparable home amp... but nowadays, it's getting closer.

There are noise issues and heat issues as well, but overall, I think most don't do it because it's *really* cheap to get their audio fix from a cheapie 100 wpc receiver than to mess with a car amp.

ferinstance: Here's a Sony that will do 90 watts x 5 for $150 from an authorized dealer

Sony STR-DG520 Home theater receiver with HDMI switching at Crutchfield.com

Hard to beat that with a big power supply and car amps.


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## elvisjer (May 13, 2008)

Hmm interesting! I'll look into pro-audio gear as well since i've got some connections in that field. I'll keep everyone updated for sure. I really want to fabricate some over the top case for the amp + power supply with rediculous LEDs, plexiglass, and stuff...it would be so fun!


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## elvisjer (May 13, 2008)

m3gunner said:


> It's not very efficient to convert 120 AC to 12 DC then have the power supply in the power amp convert back to whatever voltage your amp requires... there are losses at both conversions.
> 
> Way more efficient to just convert from 120 AC to whatever DC voltages you might need in a home amp.
> 
> ...



I understand that completely, it's just hard to find cheap amps like that playing 2Ω without going up in smoke...actually finding any home audio amps that will drop to 2Ω without going up in smoke is tough!


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## m3gunner (Aug 6, 2008)

There are lots of them, but none of them are particularly cheap. 

Older NAD, Parasound, and Yamaha are probably your best bets for relatively affordable ones. I have a NAD 2200 (from 1987) that will drive 2 ohms all day in stereo... these go for about $200-250 up on eBay.

Also remember that driving a 2 ohm load may require more than the 55 amps your DC supply is putting out. You only have about 12v x 55 amps = 660 watts assuming 100 percent efficiency on your power conversions. Most full range car amps are class A/B and are about 60% efficient at full power... so you'll have less than 400 watts available in the best case. Class D and G amps are more like 75-80% efficient, so you may be able to get more power out of those types of amps.

Take a look at the fuses in your amp... this will give you an indicator of what you'll be dealing with on the amperage front.


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## elvisjer (May 13, 2008)

I cant read. Apparently they want 100-300w but it's still the 2Ω thing that throws off a lot of the high end amplifiers, i was reading some audiophile forums about these speakers and people's audiophile amps not being able to keep up but i guess that's because a lot of the Mcintosh amps and stuff are about 250w and don't like below 4Ω...it's all starting to make sense!


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## GlasSman (Nov 14, 2006)

Look out for some QSC Mx series amps....super excellent and will drive nails.


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## GlasSman (Nov 14, 2006)

HEres one:

QSC MX 3000a Power Amp - Amplifier - Pro Live Sound DJ - eBay (item 320396664593 end time Jul-17-09 15:14:02 PDT)

This ones expensive but it gives good info on the Mx line.


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## chad (Jun 30, 2005)

The MX series does well as does the EX series, I love the EX's. Watch oout for the Mx1500A, good amp but POPULAR with DJ's and have likely had the **** knocked out of them.


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## 240sxguy (May 28, 2009)

The biggest problem besides the watkins woofers is that you are going to drive most amps easily into clipping and those emit tweeters are very fragile and not available new (unless apogee gets the new production running).

I have a pair of RSII's, ill bet the ones you have sound really good. Pro audio amps are definitely worth looking into. However, if you already have everything to use your car amp you can.. just don't drive it hard/loud. My buddy has a marantz 2230 which made 120+ per channel and couldn't handle the low impedance. Burnt the outputs in very short order.

Have fun with those things. I love "vintage" (ie. made in USA) Infinity speakers.

Evan


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## goodstuff (Jan 9, 2008)

If you want to be super cheap like me, you can modifiy computer power supplies to put out 12v. I've got one on a 60 watt pioneer 2 channel, another on a kenwood bridged and a third on a kicker 2 way crossover...hooked up to a busted ass pair of alpine 6x9 coax's and a jl12w0 in the wrong size ported box....sounds great and gets loud enough in the garage.  I'm sure most wouldn't like it this way since the supplies have some fan noise, I've got mine in a cabinet and it's in the garage anyway so I don't hear them with the music going, also I'm sure they aren't the cleanest power and will add a small amount of noise. I'd say they put out 15 amps max though so you can't run anything big.


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## aznboi3644 (Jan 25, 2009)

1000 watt home amp these days cost much less than buying a 1000 watt car amp then a power supply and batteries to support the amp.


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## daroccot (Feb 7, 2008)

Way back when I built my HT Sub with a Punch 60ix, I bought a 13.8V 30 amp power supply for about $300. The trickyist part was building a remote switching relay running on 120vac to turn the system on with the main amplifier.


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## elvisjer (May 13, 2008)

Autiophile said:


> There are good used pro amp deals out there. Just watch ebay.
> 
> There are occasionally deals on new amps as well. I picked up 2 new EP2500s for $200 a piece.


I've been doing live sound for about 10 years (yes, that means since i'm 13 but I grew up in a large church and since they couldn't keep me off the sound board they taught me to use it) and I have such a varied relationship with Behringer I've always been weary to use their products. I'm NOT a brand bias type person either, it's just in my experience i've had way to many peices of their gear literally fall apart and their pre-amps having unacceptable tone and sq. But that said, if there are good experiences with thier products I wouldn't hold a grudge and would be willing to give them another shot. Their product designers make some awesome looking products though,









I've got a TON of local music stores around me since I'm in Seattle and I think I'll give them a look, many of them are used music stores as well. I'm going to check out some good pro audio amps and hopefully i can find some that will play down to 2Ω without making smoke.


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## chad (Jun 30, 2005)

Crest Pro01 series.


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## goodstuff (Jan 9, 2008)

daroccot said:


> Way back when I built my HT Sub with a Punch 60ix, I bought a 13.8V 30 amp power supply for about $300. The trickyist part was building a remote switching relay running on 120vac to turn the system on with the main amplifier.


I just plug mine in and they are on, no switch, lol.


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## ehkewley (Jul 19, 2008)

elvisjer said:


> I've been doing live sound for about 10 years (yes, that means since i'm 13 but I grew up in a large church and since they couldn't keep me off the sound board they taught me to use it) and I have such a varied relationship with Behringer I've always been weary to use their products. I'm NOT a brand bias type person either, it's just in my experience i've had way to many peices of their gear literally fall apart and their pre-amps having unacceptable tone and sq. But that said, if there are good experiences with thier products I wouldn't hold a grudge and would be willing to give them another shot. *Their product designers make some awesome looking products though, *
> 
> I've got a TON of local music stores around me since I'm in Seattle and I think I'll give them a look, many of them are used music stores as well. I'm going to check out some good pro audio amps and hopefully i can find some that will play down to 2Ω without making smoke.


That's been my recent experience with them. Their products look cool, but don't seem to stack up. I'm currently jamming with a band that has a 300watt Behringer bass amp (loaded with knobs 'n switches), which has one of those similar VU meters. I can get it to clip pretty easily, and it struggles to keep up with two guitars and drums. I had better luck running my bass through a Peavey Ultra 120 until I got rid of it. I could be wrong, but I'd imagine their power amps don't offer much either.


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## chad (Jun 30, 2005)

Berhinger is like Peavey in that there are diamonds in the rough.


Nut peavey **** is tough as nails, whereas Behringer is ...Meh... if a Peavey item sucks... it will always suck... and never break while sucking.


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## braves6117 (Feb 13, 2008)

Autiophile said:


> Hard to beat this sort of output for the price.







Great power for the price....the only negative I've heard regarding the EP2500 is the fan is clearly audible to loud at times. But thats a simple, well documented fix, so clearly it isn't all that negative.


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## chad (Jun 30, 2005)

I rate amplifiers as to how they do being hammered for 12 hours... not with charts... the behringer wold likely be fine for a home amp.


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## chad (Jun 30, 2005)

Autiophile said:


> And they are cheap enough to own backups.


The failure and need for a backup in my world is VERY expensive in the long run.


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## chad (Jun 30, 2005)

But you can buy used Crown Grounded bridge designs, crest Pro01's, and QSC EX's all day long used for the same price.... Put them in your crawl space and forget about them


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## chad (Jun 30, 2005)

In a home heavy is not an issue so the 01's, MA/MT's EX/MX is just fine and VERY stout. No reason to go lightweight at home, those are the ones costing money.


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## SUX 2BU (Oct 27, 2008)

If you wanna go backyard ghetto cheap-cheap, just pick up a car battery charger and put a 1F cap on the output leads. The cap smooths out the ripple coming off the AC to DC conversion on the 12V side. Can get up to around 10A, but for how long I don't know. I tried this out in Electronics class way back in high-school in the early 90's and it worked.


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## elvisjer (May 13, 2008)

I managed to locally find a Nady XA1100 for $150 which was pretty dang tough to beat. My rig now is going to be bi-amping my Infinity RS 2.5 speakers with my Nady for the woofers and...well ive got a ton of vintage recievers/amps lying around to drive the mains with my fav being my small onkyo r-805X. I've got a 900w RMS cert Sony car amp w/ 12v 55a power supply running it. Not to mention vintage onkyo preamp and vintage Audio Control hifi EQ. Got to love thrift shops....all that (minus sub amp and power supply) for <$75.


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