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Old 11-23-2007, 02:10 PM   #1 (permalink)
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How many watts in 100 rms?

Hey guys, well i just bought 2 10" JL Audio w/ a 100 RMS Rockford Fosgate amp. Is 100 rms a lot? It says 100 Rms w/ 4 ohms or somethin like that. Is this good? i bought all together 2 10" JL Audio w/ box and 100 RMS Amp for $200. Will the Amp be good enough for both Subs? Isn't RMS different from watt, just like Hp from whp?
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Old 11-23-2007, 02:21 PM   #2 (permalink)
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In the future, you should be more specific about what you actually have. But based on the information given, that amp will not be enough. You should check out the specs on the subs to determine what kind of amp you need.

Also, RMS is what is used to express power, or watts, as a useable number. Since the music you listen to is AC voltage, the actual power representation is more involved than that. RMS is a DC representation of and AC signal.
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Old 11-23-2007, 02:22 PM   #3 (permalink)
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RMS is a measure of current that the subs can take consistently. The amp will not be enough power for the subs (probably), but you do have to check the specs of the subs first.

The theory goes: Figure out what configuration you are putting your speakers in (parallel or series), and then you'll know what amount of RMS watts your be pumping into your. Example: you have 2x 500 RMS watt subs rated at 4 ohms each. You wire them up in parallel, making a 2 ohm circuit. So now you know you need an amp that pushes at least 1000watts rms in to 2 ohms. The theory on purchasing an amp is get one with 2x (twice) the power than the sum of the rms watts of the speaker. You'll note that the subs can take a peak wattage of 4x the rms wattage. This allows for something called "overhead". Having overhead is good, because it allows for dynamic sound and keeps your speakers running good.

You need to make sure you're not under powering your speakers as that will damage them, more-so than if you over power them. It's kind-of like a car: there is a certain operating temperature that the car works best at...not too hot or cold. Same with speakers. The speakers use the physical movement of the cone to cool the voice coil (the thing that the two speaker wires are connected to on one speaker). If there isn't enough power pushing the speaker, the cone doesn't move much, and then can cool itself enough. This will eventually lead to major damage to the voice coil (which is more harmful to the speaker as a whole than punching a hole in the cone of the woofer...though that isn't good too)

If you have the subs model number we can figure out what you need, just post it up.
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Old 11-23-2007, 02:23 PM   #4 (permalink)
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Quote:
Originally Posted by Juss View Post
Hey guys, well i just bought 2 10" JL Audio w/ a 100 RMS Rockford Fosgate amp. Is 100 rms a lot? It says 100 Rms w/ 4 ohms or somethin like that. Is this good? i bought all together 2 10" JL Audio w/ box and 100 RMS Amp for $200. Will the Amp be good enough for both Subs? Isn't RMS different from watt, just like Hp from whp?
100 Watts RMS....that isnt enough power at all for 2 10"...it will work but you wont get any kind of good bass out of the subs.
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Old 11-24-2007, 01:10 AM   #5 (permalink)
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^you can't say that. You don't know which series subs they are and what kind of box? Let alone do you know what kind of music he listens to or what his expectations are.
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Old 11-24-2007, 01:26 AM   #6 (permalink)
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^you can't say that. You don't know which series subs they are and what kind of box? Let alone do you know what kind of music he listens to or what his expectations are.
What im trying to say is there are no 10" JL audio subwoofers that are 50 watts RMS. (100 total for the amp) Even there lowest 6" woofer is 50 watts rms. Hes going to be seriously under powering the woofers no matter what kind of box he has or music he listens to.
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Old 11-24-2007, 08:13 AM   #7 (permalink)
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Wow, the misinformation on here is insane... just hook it up and see how you like it. Unless you tell us more about the amp it's hard for us to tell.

FYI I have a Power Series 50 watt Rockford AMP that powers 2 12" woofers just fine! They have re-classed amps a bit since then but this one is an old competition piece. Amps were measured into 4 ohms @ 12 volts, so in this case my Rockford made 50 watts. But your charging system charges @ 14.4 volts and if you bridge the load to 2 ohms my particular amp (according to the birth sheet) made just over 350 watts.

If your amp is a punch 100 or something, I'll bet it'll rock 2 10's pretty decent!
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Old 11-24-2007, 01:24 PM   #8 (permalink)
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We need to know exactly what subs and amp you have to give a good answer. The OP doesn't contain enough information to come to a solid conclusion.

What Voice Coil Configuration are the subs, and how will you be wiring them?
What are the amps ratings at 1 ohm, 2 ohms, and 4 ohms? Also what brand of amp?
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Old 11-24-2007, 02:04 PM   #9 (permalink)
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You will be fine, trust me. I bet they are the WO series (entry level) for the price you picked them up for. It will sound just fine.

Last edited by Jayhawker; 11-24-2007 at 03:07 PM.
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Old 11-24-2007, 02:11 PM   #10 (permalink)
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Wow, the misinformation on here is insane...
I thought my contribution in the 3rd post was helpful. But he still hasn't responded to the make the sub, so we all don't know who's right and wrong.
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Old 11-24-2007, 07:21 PM   #11 (permalink)
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Originally Posted by Hondacivicsi23 View Post
What im trying to say is there are no 10" JL audio subwoofers that are 50 watts RMS. (100 total for the amp) Even there lowest 6" woofer is 50 watts rms. Hes going to be seriously under powering the woofers no matter what kind of box he has or music he listens to.
im with you, im a jl buff and i doubt you will get your full potential outta this 100w amp. i didnt say that it wouldnt sound good or whatnot, maybe the OP will love this setup. just play with it and see what you like. it wont hurt anything.
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Old 11-25-2007, 12:17 AM   #12 (permalink)
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Originally Posted by Hondacivicsi23 View Post
What im trying to say is there are no 10" JL audio subwoofers that are 50 watts RMS. (100 total for the amp) Even there lowest 6" woofer is 50 watts rms. Hes going to be seriously under powering the woofers no matter what kind of box he has or music he listens to.
Again I say, how do you know what he's expecting out of the system? It might not be enough output for you but it's not your car or expectations.

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Wow, the misinformation on here is insane...
Welcome to car forums and audio, everyone's an expert yet very few understand the basics of audio.

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im with you, im a jl buff and i doubt you will get your full potential outta this 100w amp. i didnt say that it wouldnt sound good or whatnot, maybe the OP will love this setup. just play with it and see what you like. it wont hurt anything.
Awesome! A JL buff. So Mr. Buff, where did he say he's trying to get full potential out of the setup? I'm a JL buff and someone who's worked with JL for going on 7 years. Does that mean I'm an Uber-buff-supreme-master chief? I think it'll be plenty enough power if the box is large enough to increase the efficiency and get some real cone movement or is ported. What if it's in a well tuned quasi-bandpass enclosure? I definitely think it'd be enough power for a phenomenal sounding setup.

Why is everyone answering questions when we don't know anything here? We don't even know what amp there is! It could be a POS Pyramid or Crunch amp, or it could be a bad ass eD, Rockford, Alpine; let alone a Genesis, Audison, Tru, etc amp with some serious cajones. STOP speculating and start asking questions. You can't answer anything until you know the whole story. Work as an installer or a salesman in a real audio shop, you'll learn what "qualifying questions" means.
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Old 11-25-2007, 12:41 AM   #13 (permalink)
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Man...

To answer the original question, 100 RMS is 100 watts at continuous power. Pay attention to RMS ratings rather than max since max ...well, crap, just don't ever go by max. Plus, if someone's advertising power by max power then just don't even buy the product. Good rule of thumb.

Watts is power. Power is a function of resistance.
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Old 11-25-2007, 01:26 AM   #14 (permalink)
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Man...

To answer the original question, 100 RMS is 100 watts at continuous power. Pay attention to RMS ratings rather than max since max ...well, crap, just don't ever go by max. Plus, if someone's advertising power by max power then just don't even buy the product. Good rule of thumb.

Watts is power. Power is a function of resistance.
this is kinda what i was trying to say toxis. 100w is 100w no matter the brand. SQ on the other hand will be different with the various brands. im not saying if it will sound good, hit hard, etc. i think that the OP can get more out of his subs with a more appropriate amp. im saying this because there isnt any 2 jl audio subs that will equal 100 wrms combined. if the OP likes the way it sounds with this setup, then fine. problem solved. i dont mean to come off argumentative if i do, im just stating my opinion.
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Old 11-25-2007, 02:11 AM   #15 (permalink)
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100w is 100w no matter the brand.
true, but not true at the same time.
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Old 11-25-2007, 03:10 AM   #16 (permalink)
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true, but not true at the same time.
Kinda what I was thinking.

Not to be argumentative, but some companies advertise a certain power but it's not true.

Follow companies that have their amps' CEA rated. That's somewhat of an "industry standard" that amps have to pass in order to have the CEA stamp. Otherwise you might buy an amp that says 100 w rms but only gives that at certain conditions. There's no law governing this, which sucks. The closest is CEA.
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Old 12-06-2007, 11:20 PM   #17 (permalink)
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from what I remember, "RMS" (root mean square) is approx 70% of an amp's rated max output, n'est pas?
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Old 12-06-2007, 11:22 PM   #18 (permalink)
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No....
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Old 12-06-2007, 11:30 PM   #19 (permalink)
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from what I remember, "RMS" (root mean square) is approx 70% of an amp's rated max output, n'est pas?
That's the definition, but that's not how it is in the car audio world.
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Old 12-07-2007, 11:07 AM   #20 (permalink)
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That's the definition, but that's not how it is in the car audio world.
Not true, that is just the way people in the car audio world believes it. RMS really is 0.707 times the peak voltage. There is no other way to really believe that.
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