# Higher RMS Amp with Lower RMS Sub



## ryanrod (Jan 16, 2011)

I searched everywhere in this forum and was not able to find much on this subject.

What is your opinion on running a subwoofer rated at 300 watts rms @ 4ohm with a amplifier rated at 700 watts rms @ 4ohm with the gain on the amp turned down? Is it possible to run this setup without damaging the components and producing clean sound?

My prospective setup is as follows:

AMP: ARC Audio KS 300.2 - 700w @ 4ohm bridged
SUB: JL Audio 12w3v3 4ohm single voice coil - 300w "optimum" by JL
BOX: 1.2 cu ft Sealed

My reasoning behind the amp choice is due to the fact that I want great sq, durability (long lifetime) and good looks. I also want to give the sub enough power without the amp having to work too hard.

I own the 12w3v3 and am considering purchasing the ARC Audio KS 300.2. I was running the 12w3v3 on a PPI PC 2150 which supposedly produces 600w @ 4ohm bridged. However this amp always seemed to be straining to produce power and now it is dead.


Thank you for your knowledge!


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## dman (Dec 21, 2008)

POWER does not destroy speakers, DISTORTION does.......

Yes you will be fine...

rule of thumb is to take the MAX woofer rating, and match a amp to that....


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

You'll be fine, and you'll have awesome dynamics..


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## WhyUmad (Dec 18, 2010)

My friend runs a JL xd600.1 on a 12w3 its been fine for months and I just put JL xd600.1 on a 10w3 in someones car, both in ported boxes. You should be fine


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## ZAKOH (Nov 26, 2010)

I think you just need to be careful with gains.. start with the minimum setting, then turn it up slowly to calibrate the sub output to match your other speakers. Ideally calibrate the amp gains so that your normal listening volume is somewhere at the 70-80% level of head unit's volume knob. In that case, it will be harder to damage speakers even with the head unit volume knob.


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## sqshoestring (Jun 19, 2007)

It will work until it blows the sub if you lean on it too hard. What I find is you can't run them as hard if it hits xmax, because the amp has more headroom. If they are similar ratings then the amp pukes on a hard note and does not xmax the sub when near max input the sub can handle. Now ratings are vague, that sub might take a lot more if you don't run bass music because music varies power so much its not constant and JL are pretty good subs it may take a lot more to xmax it/etc.

Some of those PPI amps the outputs fell off the boards, I don't recall what one you have but for transistors on the sink the solder comes off the board. Those ones the legs lay in the solder. It can make them seem to lose output over time when some come off and others are still working, I had one do it.

To take it easy on an amp, run higher ohm load to reduce power.


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## Oliver (Jun 25, 2007)

dman said:


> POWER does not destroy speakers, DISTORTION does.......
> 
> Yes you will be fine...
> 
> rule of thumb is to take the MAX woofer rating, and match a amp to that....


NEVER listen to this ~ YouTube - Jimi Hendrix Purple Haze ~ unless you have a new set of speakers on hand 



> Manville on average power over time:
> 
> The only thing that thermally damages speakers is power... more specifically: average power over time.
> 
> ...


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## DBfan187 (Feb 26, 2010)

I'm in the same boat bro, I got a 10w3v2 D2 on an Opti2000D. It goes BOOM like so, but I have to dial down the output level A LOT! Cause it bottoms out like crazy! lol


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## Maveri9720 (Apr 19, 2011)

I agree. Just be careful with the gains initially and don't get caught up in the moment with a remote gain and try to crank it up. Headroom is a good thing.


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## ryanrod (Jan 16, 2011)

I bought the ARC AUDIO KS 300.2 and it should arrive today, so I'll let you guys know the results.


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## Fricasseekid (Apr 19, 2011)

I'm in the same situation myself. I've been running my speaker at (& I estimate) double the RMS rating for about a week now. It sound great and haven't heard any signs of bottoming out, clipping, or distortion of any kind. I'm just worried about frying my voice coil. Why is this not a concern aside from distortion?


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## RedAggie03 (Jun 7, 2009)

I'm running the 12w3v3 as well. I'm currently running it at 300x1 at 4 ohms on my old Sony monoblock amp. I'm going to upgrade to the JL XD600.1 I think. 400 watts at 4 ohms should be perfect.


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## sqshoestring (Jun 19, 2007)

Fricasseekid said:


> I'm in the same situation myself. I've been running my speaker at (& I estimate) double the RMS rating for about a week now. It sound great and haven't heard any signs of bottoming out, clipping, or distortion of any kind. I'm just worried about frying my voice coil. Why is this not a concern aside from distortion?


You can often play it louder with more power, *if it does not xmax* and cause mechanical damage. Why, because they rate the sub for a margin of safety likely safety from clipping amps. If you use that margin with clean power that contains less energy than clipping does....it goes louder. But you have to be careful, know the sub well, and likely it works better for normal music not bass music with sine type tones. Normal music carries less energy or does not hit constant like bass tones...so the VC gets a rest between. Of course none of this matters at all until the last ~20% (maybe less) on your volume control when the extra power would get used.


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## Fricasseekid (Apr 19, 2011)

By extra power, do you mean more voltage from the preamps?


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## sqshoestring (Jun 19, 2007)

I mean if you get a 200rms amp and a 200rms sub, maybe (for example only) the sub can take 400rms for a short time. So someone clips the 200rms amp to 400rms it should not blow up right away. But you only get 200rms of clean power before it clips. So you get a 400rms amp and you play it at 300rms+ clean and it goes louder, is very clear. You are still under 400rms its not likely to blow. Now ratings are all different, but if they were all the same this would be true. You have to gain the amp to find out where that place is you can play them too. You risk toasting them, just saying the above is commonly done and successful if the operator has some control and sets it up carefully. How far you go is all in the gain, but even gain is negotiable because the levels of source material vary as well.

Extra power is the last part of the volume you use, where you have it set to go before it clips. Since power is applied in a log scale the power grows the most right at the end. Look up a 'linear taper'. You might be at 50rms at 75% volume, and 300 at 100%, or whatever the numbers are.


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