Understanding RMS vs Peak

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Wigzter
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Joined: Fri Mar 28, 2014 1:25 pm
Location: Tampa, FL

Understanding RMS vs Peak

Post by Wigzter »

Hey PP people!

So if any of you have read any of my recent posts you know I'm a car audio noob. But with a lot of self research and help from you guys I've managed to setup my ride sounding really good and tuned to perfection IMO.

Anyways, I know that RMS power is continuous power and Peak power is the punchy boom ones right?

So my question is, my two Ti212D4's are 600RMS and 1200 Peak a piece so since I have two of them, on paper I should be around 1200RMS and 2400 Peak. After researching JL audio subs, they're for example 100-400 RMS. So I'm guessing it optimal inbetween that range. But what about my subs? Is it optimal around 1200RMS or is that the max for both my subs. So what would be my optimal range?

With a DMM I tuned it to about 34 volts. 1200 watts is 34.6 volts for my system setup. So just shy of 1200 watts. But it doesn't sound crystal clear bass until I hit 28/40 volume. Which is where I normally listen to it.

Basically I don't want them underpowered and I don't want to blow them either.

Thanks again PP for the help in advanced!
06 Chevrolet Tahoe
Bose Factory System w/ PAC Line Out Converter
(2) Bose Tweeters
(2) 4" Bose Midranges
(4) 6.5" Bose 4peakers
(1) Ti21300.1 Amplifier on Stinger 4ga Power/Ground
(2) Ti212D4 Subwoofers wired to 1ohm load
trickyricky
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Re: Understanding RMS vs Peak

Post by trickyricky »

RMS = Root Mean Square ....its a formula, peak is just 2x the amount of RMS. So basically RMS is the SAME as PEAK regarding power output, Peak just makes it seem much more powerful (the amp that is, lol).


When it comes to subwoofer ratings such as RMS and peak...its not the same as an amplifier. If you read (thats if they include any fine details) you'll see that if your subwoofer is rated at 600watts RMS then that basically means your subwoofer can handle 600watts of power on a certain fhz range. The peak rating of the sub is not a constant rating more like a quick burst 1200watts, try feeding it that much power constantly and you'll most likely burn up the coil/sub.


That said you can safely feed those subs anywhere from 300-600watts (of course 600watts is where they will shine).


My subs claim to be 600watts RMS as well, have two of them and I only feed them around 600watts total to both of them...plenty loud and pretty clean.


When you where setting your gains (to get that voltage) did you have a sine wave playing? If so how the hell could you stand 1200watts of sine wave?
Wigzter
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Location: Tampa, FL

Re: Understanding RMS vs Peak

Post by Wigzter »

Well this is basically what it did, I picked a 50Hz freq loop and disconnected the subs at the amp and put the multimeter there instead. I have a stock head unit so I'm sure that affects my system as well. But I played the 50Hz loop until I reached 34 volts. Then reconnected the subs and started playing music again. I mean it doesn't sound bad at all but I feel like it really shines when I'm at about 28/40 volume. When I tuned it, I was at 30/40 volume.
06 Chevrolet Tahoe
Bose Factory System w/ PAC Line Out Converter
(2) Bose Tweeters
(2) 4" Bose Midranges
(4) 6.5" Bose 4peakers
(1) Ti21300.1 Amplifier on Stinger 4ga Power/Ground
(2) Ti212D4 Subwoofers wired to 1ohm load
vwdude
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Re: Understanding RMS vs Peak

Post by vwdude »

Something that you might not know about is clipping. If you used an oscilloscope instead of a dmm you would have seen sine wave on the scope. A clipped signal means that the peaks are clipped, so call them plateaus rather than waves. They can also be called square waves. That's distortion. You really don't want to tune the way you did it without a scope to very that you are not clipping.

In regards to the other questions, RMS are the only useful numbers. Peak and max numbers are marketing things, used to sell products to the walmart crowd. Peak power on an amp is often like peak MPG on a car. It's measures for an instant during ideal conditions. I have seen that number over 4x the rated RMS value in some cheap amps.
A few of these and a few of those.
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ttocs
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Re: Understanding RMS vs Peak

Post by ttocs »

never paid a bit of attention in the power handling #'s of my subwoofers. One of the most useless numbers on the spec sheet. Build the box right, keep the signal clean and unclipped and throw as much at them as you can.
what else can I say I am a grumpy asshole most of the time.
Kirghiz
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Re: Understanding RMS vs Peak

Post by Kirghiz »

ttocs wrote:never paid a bit of attention in the power handling #'s of my subwoofers. One of the most useless numbers on the spec sheet. Build the box right, keep the signal clean and unclipped and throw as much at them as you can.
This.

The published RMS power specs on subs are a "safe number" that the manufacturer deems optimal for the top end power. If you have clean power, meaning unclipped, and a voltage source feeding the amp a constant voltage that doesn't change much, you can easily exceed the RMS power on subs by 20-25% safely with proper gain and crossover settings on the amp. Sometimes you can exceed it more than that if you know what you're doing. I had a Ti210 running off the sub channel of an Elite.5 that fed it 750 watts rms, and the sub took it like a champ.

The thing you need to remember is that you aren't actually putting the full power of the amp to the subs until you are beating on them and cranking it. If you are exceeding the rms power you might not want to go full tilt on three hour runs or anything, but you can certainly bang on it for an hour or better without too much issue. If you start to hear distortion, smell burning voice coils, or that sort of thing, just back off the volume some. That holds true even if you are within the RMS range. You can have a 300 watt amp, a 600 watt sub, dial the gain and bass boost way up, and still conceivably cook a sub, though I'd say the amp would fail first lol.

The point is, you can do nearly anything you want with proper tuning of the system, and having some sense about you when you crank it.
Being loud without good sound quality is pointless, but having good sound quality without being loud is also pointless.
Wigzter
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Location: Tampa, FL

Re: Understanding RMS vs Peak

Post by Wigzter »

This is starting to make a lot more sense now. Thanks guys, I'll look into purchasing an oscilloscope when I get paid on Friday.

So on paper, how would I tune it with the oscilloscope? I'll do some more research on it and maybe watch a few YouTube videos on it.

Pretty excited to see the changes in sound when I do it. Even if it's not much, everything right now sounds great. But one thing I do notice is that when I play that Downlink song you sent me Kirghiz, it sounds extremely clean except for one note, all I can describe it is a "Dun - dun dun - dun". I'm sure you know the one I'm talking about. But that note I always turn down the knob a little because it sounds forced, or too much power going to them, but the rest of the song sounds great.

EDIT: If anyone can recommend an oscilloscope to me that works great and not super expensive that would be awesome. I'm looking to keep that on budget around $150 or less roughly, a little more is okay.
06 Chevrolet Tahoe
Bose Factory System w/ PAC Line Out Converter
(2) Bose Tweeters
(2) 4" Bose Midranges
(4) 6.5" Bose 4peakers
(1) Ti21300.1 Amplifier on Stinger 4ga Power/Ground
(2) Ti212D4 Subwoofers wired to 1ohm load
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NOT 2 OLD YET
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Re: Understanding RMS vs Peak

Post by NOT 2 OLD YET »

Totally agree with these guys! If the power is clean and stable you are all good! I have always lived by 1 rule, just like assumption- distortion and voltage drops are the mother of all fuck ups! I have seen guys cook good subs with a shit amp and vice versa because of THD levels. Like what was said above it is for marketing! You can hit a sub with much more than rated power as long as it is CLEAN!
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ttocs
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Re: Understanding RMS vs Peak

Post by ttocs »

http://www.ebay.com/itm/Mini-Storage-Di ... 5895009fc4

Tuning your system with a volt meter is like trying to do find carving with a sledge and a flat head screw driver. It will get close but if you really want the right tool for the job that is where the scope should be in every tool box.
what else can I say I am a grumpy asshole most of the time.
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kg1961
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Re: Understanding RMS vs Peak

Post by kg1961 »

Np I can mold like that..just kidding most have way more skils than I
Think of this for most
Rms-normal not clipping the amp everyday long term set up
Peak is spl and its a 2 min and on after that you.void warranty and your item will fail it just when
most of my gear is gone :liar:
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Kirghiz
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Re: Understanding RMS vs Peak

Post by Kirghiz »

Wigzter wrote:But one thing I do notice is that when I play that Downlink song you sent me Kirghiz, it sounds extremely clean except for one note, all I can describe it is a "Dun - dun dun - dun". I'm sure you know the one I'm talking about. But that note I always turn down the knob a little because it sounds forced, or too much power going to them, but the rest of the song sounds great.
I'm not sure what that might be unless that particular note is lower frequency than the tuning of your port. I don't get that on mine. Cranking notes that are lower than the tuning frequency of the port can cause damage to subs too. To be safe you might want to check what the tuning frequency of your enclosure is, and set the subsonic filter on your amp to to a couple hz below that frequency to filter out frequencies below your tuning. That might fix that.
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stipud
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Re: Understanding RMS vs Peak

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