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Discussion Starter · #1 ·
Ok, heres what I have: All Memphis.

Class AB Power Reference Amplifer 16-PR2.50 50w RMS x 2 @ 4ohms or 70w RMS x 2 @ 2ohms
2 Power Reference Subwoofers 15-PR10D4 250w RMS

They are in a ported enclosure and ran using the stock head unit.




Heres my question,

A guy at the place I got my system done told me my amp was rated at 500watts RMS but would do 600. According to Memphis, my amp is only rated at 50 watts per channel with two channels. My subwoofers are rated at 250w RMS each. So doesn't that mean each is underpowered by 200watts? If so, then WTF!

Now don't get me wrong, my subs sound NICE. But i don't understand this whole sub and amp deal. The reason why I'm worried at all, is because I was considering getting two 12's and using the same amp.

The subs I want to get have the same power rating as the two 10"s I have. But I just realized my amp wasn't what I thought it was so I'm completely confused now. Any help/explanation would be great.

Thanks everybody.
 

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First of all a Class AB amp is not really needed for subs. Your exisiting amp would make a great amp for the door speakers, but it makes little sense for a sub.

You get a lot more kick for your money with a mono sub amp, which trades off wide band response, which is not needed at all for a driver that is crossed out at 65 hz, for more low end grunt and less cost per watt.

You can get inexpensive no-fancy-name sub amps for as little as $100 that sound great and will drive your sub much better. You are probably losing at least a half octave of bass extension with your existing amp, and it is so underpowered that you are probably clipping the amp frequently.

If you are still using the OEM head unit to run your door speakers, you can certainly put the memphis amp to work there instead. Otherwise, I'd sell it for what you can get for it and buy a sub amp instead.
 

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According to the Memphis website:

http://www.memphiscaraudio.com/products/amplifiers/class-ab-power-reference-amplifiers/

That amp is rated at 130 watts RMS bridged, or 70 watts RMS per channel into a 2 ohm load. So yes, I'd say the person who sold you that amp stretched the numbers quite a bit. I'd also agree that it's really not enough power for your subs.

Since you have two dual voice coil 4 ohm subs, I'd personally look for an amp that does 500-600 watts RMS (not max output) into a 2 ohm mono load. This way each sub is getting around the RMS rating of 250 watts. Sure, you can use the amp you have, but those subs aren't very efficient, and would probably be more impressive sounding with a lot more juice than 70 watts RMS.

FWIW, there is nothing wrong with using a Class A/B amp for sub duty. They just aren't typically as efficient and flexible as a class D amp.
 

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Sounds to me like your subs are getting pretty much no power. Even if you designated that amp entirely just to your suwoofers, you would still be only using about 30% of the subs actual capabilities. You would be much better off having a class D amplifier with a mono channel output and bridging the two subwoofers together.

For example, the amp I just bought off of a member here:

Memphis Audio Power Reference 500.1

It runs a good amount of juice RMS and peaks out quite high for when you would need it. That is probably what you should be looking at if you like Memphis gear a lot.
 

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Discussion Starter · #7 ·

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Sounds like your speakers are getting good power, but definitely not the subwoofers.
 

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Discussion Starter · #9 ·
my subs make the rear seat passengers want to kill themselves. They are loud. The subs sound nice. Thats what is confusing me. I'm gonna go make sure that the actual amp is the same on on the box.
 

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It just doesn;t sound like it here from the video. If they are loud, though, then you are probably getting sufficient power. Maybe they installed a second amp?

This is the exact reason why I do this kind of stuff myself. I know that it is done right and if there are any problems, I know exactly where to look for them.
 

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That amp is definately underpowering your subs. If your subs are 250w RMS, then that's what you will need to run for each sub. So, something that can push 250w RMS on each sub. Stick w/ a mono block that's 500+ RMS, or a 2 channel that can push that RMS on each channel. If you think it sounds good now, imagin how it'll sound when they are properly powered.
 

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Discussion Starter · #12 ·
[quote author=que link=topic=136716.msg2947197#msg2947197 date=1235059137]
That amp is definately underpowering your subs. If your subs are 250w RMS, then that's what you will need to run for each sub. So, something that can push 250w RMS on each sub. Stick w/ a mono block that's 500+ RMS, or a 2 channel that can push that RMS on each channel. If you think it sounds good now, imagin how it'll sound when they are properly powered.
[/quote]

Yep, the amp matches the box. My subs are severely underpowered. you'd have to hear them in person. They def sound good, but like you said, what will they sound like when I get the right amp :shock:

I'm bout call up somebody and bitch them out.
 

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Discussion Starter · #13 ·
OK... peeps. I just called my shop and they explained everything. Numbers are almost useless when it comes to this stuff. Thats just my take. I'm going to just trust them.

My current subs sound great (you need to hear them in person), its just those numbers got me worried. I'm still going to upgrade to a better amp though :shock: And they said that to upgrade to 12's with the amp would be about $150 all together. :shock: :woohoo:


I'll get back to yall and let you know what happens
 

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Two 12" subs and an amp for $150? I wouldn't believe them on that. If you stuck to your Memphis gear, you would be looking at probably twice that just for the equipment.
 

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Discussion Starter · #15 ·
[quote author=daustin link=topic=136716.msg2947534#msg2947534 date=1235065141]
Two 12" subs and an amp for $150? I wouldn't believe them on that. If you stuck to your Memphis gear, you would be looking at probably twice that just for the equipment.
[/quote]

I'm pretty sure that is the price after trading in my current subs and amp. And every sub at my place is buy one get one free. Literally. If you buy one L7, you get another L7 free.
 

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I didn't know your shops do trade-ins. Most of the shops I hear of just sell you the stuff and hand you back what you had, since it's yours.

If they're willing to do it, then do it. I still say that you should look into self installation because then you know it's all done right and you know exactly how everything is set up, so that if / when anything goes wrong you know exactly the places to look for problems instead of poking around blindly.
 

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Discussion Starter · #17 ·
[quote author=daustin link=topic=136716.msg2947550#msg2947550 date=1235065488]
I didn't know your shops do trade-ins. Most of the shops I hear of just sell you the stuff and hand you back what you had, since it's yours.

If they're willing to do it, then do it. I still say that you should look into self installation because then you know it's all done right and you know exactly how everything is set up, so that if / when anything goes wrong you know exactly the places to look for problems instead of poking around blindly.
[/quote]

I will give my shop credit. They have plenty of happy customers. I trust them to do a good job. the reason they might do a trade-in (I'm assuming they meant trade-in) is because I bought the subs with a two year warranty from them. Everything I have is from that place.

I guess if they wanted to, they could plug the traded-in subs into the wall and pay 20 bucks for some brand new ones to be shipped in under warranty hahahaha
 

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Numbers game just a bit...

Not quite sure what your shop told you (and if you are happy with them, thats great.)

If you are bridging your subs to the amp on a 2 OHM load, they are seeing 130 RMS. Underpowered? Slightly. Does that mean they won't sound good? No.

FYI, doubling the 130 to 260 watts RMS will only give a small bit anyway. As we double the RMS power to a speaker, we get a +3dB bump in loudness. That's barely enough to detect by human hearing at 6 feet away.

10 watts = 99 dB
20 watts = 102 dB
40 watts = 105 dB
80 watts = 108 dB
160 watts = 111 dB
320 watts = 114 dB
640 watts = 117 dB

So chances are that your subs can handle a bit more, and would be happy to do it, but it doesn't mean that they don't sound good now.
 

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Discussion Starter · #19 ·
[quote author=Zanilth link=topic=136716.msg2947674#msg2947674 date=1235068222]
Numbers game just a bit...

Not quite sure what your shop told you (and if you are happy with them, thats great.)

If you are bridging your subs to the amp on a 2 OHM load, they are seeing 130 RMS. Underpowered? Slightly. Does that mean they won't sound good? No.

FYI, doubling the 130 to 260 watts RMS will only give a small bit anyway. As we double the RMS power to a speaker, we get a +3dB bump in loudness. That's barely enough to detect by human hearing at 6 feet away.

10 watts = 99 dB
20 watts = 102 dB
40 watts = 105 dB
80 watts = 108 dB
160 watts = 111 dB
320 watts = 114 dB
640 watts = 117 dB

So chances are that your subs can handle a bit more, and would be happy to do it, but it doesn't mean that they don't sound good now.
[/quote]

Thanks so much man. That makes everything make sense. I just couldn't begin to understand how my subs would sound as good as they do with that little of power.

Anyway, it looks like I'm gonna end up going with two 12"s and an upgraded amp. I'll be sure and keep yall updated.
 

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If you are bridging your subs to the amp on a 2 OHM load, they are seeing 130 RMS. Underpowered? Slightly. Does that mean they won't sound good? No.
Actually, it means they are sharing 130 watts RMS because each sub is hooked up to one channel of the two channel amp, at a two ohm load. Each channel puts out 70 watts into a two ohm load, and that really isn't much power for a 10" sub, no matter how efficient it is.

That amp would no doubt go into protection if you tried to bridge it to a two ohm load.

I still think the shop sold the OP that amp because they were trying to get rid of it. Not really an ideal configuration.
 
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