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Thread: RMS |
    
Bronze Member Username: Zbruski
Post Number: 24
Registered: Jun-04
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| Posted on Friday, July 09, 2004 - 01:28 am: |
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When an amp claims it puts out "x" watts RMS, what exactly does this mean? Does it take into account a given volume or does it mean at full volume it averages "x" watts? Someone please explain this to me. |
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| Posted on Friday, July 09, 2004 - 05:28 am: |
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RMS means "Root Mean Square" or something like that. It basically means the average amount of continuous wattage that can be pushed out by an amp. This is the number you want to look at, not the max wattage. So if the RMS is 300 you shouldn't push it any harder if quality of sound is your main concern. but its alright if you push your amp harder. |
Gold Member Username: Glasswolf
NorthWest,
Michigan
USA
Post Number: 3839
Registered: Dec-03
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| Posted on Friday, July 09, 2004 - 01:37 pm: |
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yes the RMS rating of an amp is at full output. It's the maximum continuous "average" of power the amp produces.
The actual power fluctuates constantly and by a large amount in reality since the signal being amplified is very dynamic, but the RMS average is a good way to see what the amp can sustain for prolonged periods as opposed to a brief momentary output.
the root mean square average is used for AC signals.
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Gold Member Username: Glasswolf
NorthWest,
Michigan
USA
Post Number: 3840
Registered: Dec-03
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| Posted on Friday, July 09, 2004 - 01:39 pm: |
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here's more information:
http://www.doctorproaudio.com/doctor/temas/powerhandling.htm
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New member Username: Loudnobnoxious
Post Number: 7
Registered: Jul-04
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| Posted on Sunday, July 11, 2004 - 01:15 am: |
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RMS is full output? That's the amount of wattage an amplifier can produce without producing as much strain as running it wide open for a period of time.
What you get at full output (for most companies its if lightning strikes the amp) is called peak power. This number is completely irrelevant. |
Gold Member Username: Glasswolf
NorthWest,
Michigan
USA
Post Number: 3880
Registered: Dec-03
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| Posted on Sunday, July 11, 2004 - 09:12 am: |
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Cheif, you're a bit off here. Allow me to clarify this.
the RMS rating of an amplifier is a measure of what the amp can produce continuously at full output.
Peak, PMPO, MAX power etc is a measure of what the amp can produce for a brief moment at full output.. similar to burping a system at an SPL event.
a "1200 watt RMS" amp will only produce a continuous 1200 watts (average) at full output.
when you drop to half the audible volume from full, the power produced drops by a factor of ten, to about 120 watts. Reducing teh volume to half again the audible volume will result in the amp producing about 12 watts.
As you can see, power drops quickly with volume since this isn't a linear scale when dealing with decibels.
remember:
+3dB = 2X the power or going from 1 sub to 2 subs with the same amount of power divided between the total number of subs.
+10dB = 10X the power & 2X the audible volume
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Silver Member Username: Iamduff_87
Michigan
America!
Post Number: 106
Registered: May-04
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| Posted on Sunday, July 11, 2004 - 12:47 pm: |
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so 1 sub from a 310RMS amp would be 3 dBs lower than 2 subs from a 310RMS amp? this is at full output with the same song?? Thats pretty neat. would the same work for the subs and so on or would the power not be enough since it was distributed out too much??
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Bronze Member Username: Loudnobnoxious
Post Number: 13
Registered: Jul-04
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| Posted on Sunday, July 11, 2004 - 01:05 pm: |
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Glass i've got ya now. It seemed a bit off before but now all is right hehe |
Gold Member Username: Glasswolf
NorthWest,
Michigan
USA
Post Number: 3886
Registered: Dec-03
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| Posted on Sunday, July 11, 2004 - 01:24 pm: |
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"so 1 sub from a 310RMS amp would be 3 dBs lower than 2 subs from a 310RMS amp?"
that's very general, but yes, that's how it works. more surface area, more excursion, so more displacement. this is if both subs are the same, in the same kind of box, yadda yadda.. "all else being equal" you know. There are always other factors that can affect this of course.
"this is at full output with the same song??"
well, at any output really.. it'll always be about a +3dBA difference.. song, test tone, what have you.
You can get the same +3dBA increase by using the single sub and doubling the power to it (within the sub's allowable power handling, and without reaching Xmax of course) so going from 150 watts with one sub, to 300 watts with the same sub will yield the same increase of 3dBA.
"would the same work for the subs and so on"
you mean like going from 2 to 4 subs and such?
yeah same basic increase. same with power.
again though, there are limiting factors. This is just a general rule of thumb in regards to power and colume and how they relate to each other.
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