Will this amp bust my sub?

stevens

Senior member
Aug 11, 2001
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Well actually i dont have an amp but before i do i want to make sure that i am not going to overpower my sub and bust it. I got a jl 10inch sub of ebay for $25 and so now i need an amp to go with it. I am looking at a US Acoustics amp that does 280 watts rms bridged but my sub is only rated at 125 watt rms. I can get a lower model of the amp that does 160 rms but the difference in the two amps is only $10 so i would like to get the more powerfull one. Is there anyway to run my sub off the more powerfull amp without having the amp blow the sub out? Thanks

Steven
 

John

Moderator Emeritus<br>Elite Member
Oct 9, 1999
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Distortion is what blows speakers, not over-amplification.
 

Rallispec

Lifer
Jul 26, 2001
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better to be safe than sorry.. send the amp and sub to me and i'll test them out for you.


(it will be fine.. just dont turn it up louder than the sub can handle.. like john said, the distortion kills it, not the amps)
 

TheNemesis

Golden Member
Aug 26, 2000
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Originally posted by: John
Distortion is what blows speakers, not over-amplification.


*Cough* Bullsh!t *Cough*

If you send 500w to a sub that can only handle 200w, how is that distortion...Too much power can easily blow a speaker.

 

glen

Lifer
Apr 28, 2000
15,995
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You don't much power for subs.
I am running 2 JL 12s off 50 watts and it will make your ears bleed.
 

John

Moderator Emeritus<br>Elite Member
Oct 9, 1999
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Originally posted by: TheNemesis
Originally posted by: John
Distortion is what blows speakers, not over-amplification.


*Cough* Bullsh!t *Cough*

If you send 500w to a sub that can only handle 200w, how is that distortion...Too much power can easily blow a speaker.

Are you sure you understood the meaning behind my post? The way most people blow speakers is under-powering them and thus turning the volume up past 3/4 which typically results in distortion. The more clean power you have, the less chance you have to distort the signal. I drove a trio of 300w rms JL10W6's w/ an Arc 2500CXL (1100w of clean power) which was in turn over-powering them, but there was no distortion. Sure you could argue that a 1000w amp that outputs a clean signal will overdrive a given speaker, and I do agree, however in regards to the original post we are not dealing with "insane" power.
 

gogeeta13

Diamond Member
Dec 31, 2000
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it's all relative, SPL depends on your cabin size, sealed or ported, and other factors..
 

stevens

Senior member
Aug 11, 2001
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nice, you got 10w0 for 25 bucks !? Good find.

Yeah and it comes with a custom made walnut enclosure!

You don't much power for subs.I am running 2 JL 12s off 50 watts and it will make your ears bleed.

Yes i do understand that i dont need this much power but the amps arnt too expensive. The 160rms amp is $79 and the 280rms amp is $89, so i would rather spend the extra $10 on the extra power.

So from what i can gather i will be fine running the sub off the more powerfull amp?
 

John

Moderator Emeritus<br>Elite Member
Oct 9, 1999
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So from what i can gather i will be fine running the sub off the more powerfull amp?

Yes.
 

RSI

Diamond Member
May 22, 2000
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Just don't be moronic with your sound system and it will be fine in either case. :)
 

mattyrug

Golden Member
Sep 25, 2000
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Yes i do understand that i dont need this much power but the amps arnt too expensive. The 160rms amp is $79 and the 280rms amp is $89, so i would rather spend the extra $10 on the extra power.

Depends on the quality of the Amps!(this is for another thread though!) ;)
Answer to your question is probally not, but You're right on the edge of too much power. Too much power will over-excurt the driver, and cause it to prematurely fail due to overheating.
The general rule of thumb (in Pro Audio) is double the amount of Program (or RMS) power that a speaker requires (Amplifiers are usually rated in peak power). Distortion isn't going to kill your speakers, Overheating (over-excursion from too much power ), Square Waves will, or DC will. I hope we all know what a Square Wave is.... as far as DC, I hope we all know what this is as well......
Are you going to be listening to it at full volume all the time? Also that is for the RMS method of measurement, what's the highest peak it can take, (probally 250 watts?)? What Impedance is that 280watts amp rated at? 8ohms, 4, 2? What's the impedance of the speaker? If that 280 watts is peak, then yes you're safe. If the RMS Rating is true then that's -3dB before clip (560 watts peak) then it's probally gonna be a bit too much for the speaker.
don't wanna go into length, but 280 watt amp @ 4ohms is gonna roughly translate into 160 watts @8ohms (Mileage WILL vary from amp to amp).

And just remember that it takes roughly 2x the power, or you must EXACTLY double your speakers and amps to get 3dB more of Volume.

This is how it's explained in Yamaha's Amplifier Guide -
Speaker Power Handling:
Continuous........ 150 Watts
Program (RMS)... 300 Watts
Peak................... 600 watts

Continuous refers to the level of long term average power that the speaker will handle. This is measued at the factory usually using a sine wave, or tome. This is usually a worst-case scenario. This is something that would represent the voice coils heating and failing over a long period (more than 1/10th of a second)
Program refers to measurements using a test signal, usually a varying toned sine wave (more like real-world use). These have less heating effects for a given power level. (more like actual music) or over medium length periods (like a minute or so)
Peak is in reference to the maximum instantaneous short term power that a speaker can handle (general rule is no more than 1/10th of a second).

So you'd wanna get a 600 watt amplifier?? well, yes and no. a 600 watt amp might only be running at 6dB below clip nominal (150 watts minimum). There are many variables to this rule of thumb though, some cheaper amplifiers may choke under load, and will never deliver the full 600 watts, and may even clip at -3dB, thus sending a square wave to the speaker. A decent 300watt Amp will do the job just fine.
Of course this is in a perfect world, so your mileage may vary!
 

Operandi

Diamond Member
Oct 9, 1999
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US Acoustics is crap, there is a reason they are 1/2 the price of a MTX or Rockford they skimp on quality, to save money. Will the amp hit 280 watts? maybe will it sound like crap? definitely.
 

Spoooon

Lifer
Mar 3, 2000
11,565
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US Acoustics aren't that bad. I'd rather get one of those than a Jensen or something else in that price range. Besides, a watt is a watt. It doesn't matter if it comes from a 1000 dollar amp or a 10 dollar amp. But turning the gain all the way up on that 10 dollar amp is a good way to mess up your sub. ;)
 

Harvey

Administrator<br>Elite Member
Oct 9, 1999
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Originally posted by: John
Distortion is what blows speakers, not over-amplification.
< Enn-n-n-n-n-nnnh!!! > (Game show buzzer sound) WRONG ANSWER!

Distortion can contribute to speaker failure, but it's still POWER that blows the voice coil. Distortion. especially hard clipping. just puts more energy into the wave form than a sine wave. If you exceed the power rating of the voice coil, it will eventually overheat and fry.
 

Operandi

Diamond Member
Oct 9, 1999
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US Acoustics aren't that bad. I'd rather get one of those than a Jensen or something else in that price range. Besides, a watt is a watt. It doesn't matter if it comes from a 1000 dollar amp or a 10 dollar amp. But turning the gain all the way up on that 10 dollar amp is a good way to mess up your sub.

Yeah, you can prolly do worse but don?t fool your self into thinking that an US Acoustics amp rated at 300 watts is going to perform like a MTX rated at 300 watts. US Acoustics isn't working miracles that allow them to build amps at ½ the cost. I'm sure that under special conditions in their labs that amp will out put 300 watts cleanly but good luck trying to do that in your car. You get what you pay for it?s that simple.

I think you would be much better off with a quality amp with a lower, more believable RMS rating; this Alpine looks decent for example.
 

Operandi

Diamond Member
Oct 9, 1999
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How the hell do you fry a speaker with an amp that has a high power rating?

LOL, I don't get it...

If your gona kill a speaker your going to have to use more power then what it can handle otherwise its just not gona happen.

How?

One of two things will happen, one the voice coil will overheat causing the driver to smoke and if your lucky burst into flames, pretty exciting :). Two, you push the driver's suspension past its limits and blow the cone, surround and various other parts to pieces, also quite pleasing :).
 

TomC25

Platinum Member
Oct 12, 1999
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I sent way too much power to a sub one time and it melted the voicecoil and the sub cone was frozen in place.

I got a free replacement. :)
 

TheNemesis

Golden Member
Aug 26, 2000
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Originally posted by: Operandi
US Acoustics aren't that bad. I'd rather get one of those than a Jensen or something else in that price range. Besides, a watt is a watt. It doesn't matter if it comes from a 1000 dollar amp or a 10 dollar amp. But turning the gain all the way up on that 10 dollar amp is a good way to mess up your sub.

Yeah, you can prolly do worse but don?t fool your self into thinking that an US Acoustics amp rated at 300 watts is going to perform like a MTX rated at 300 watts. US Acoustics isn't working miracles that allow them to build amps at ½ the cost. I'm sure that under special conditions in their labs that amp will out put 300 watts cleanly but good luck trying to do that in your car. You get what you pay for it?s that simple.

I think you would be much better off with a quality amp with a lower, more believable RMS rating; this Alpine looks decent for example.

Bullsh!t. Have you ever owned a US Acoustics and tested the RMS ratings? They have a GREAT reputation at forums that people that know car audio hang out at, they're known as a great budget amp. You say MTX is a great company? Their amps may be DECENT(while still budget) but IMO their subs suck. Don't trash a company when you have absouletely no basis to do it on.