Rms?

[Ormist 10+ year member]

What exactly is RMS? I was told that the max wats suggested by my interior speakers is not what I should py attention to but instead should just find out the RMS of my speakers....

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[stalephotograph 10+ year member]

rms is the continuous amount of wattage youre pushing to your subs w/. most of the time if you see an amp or sub w. 1200 watts max its generally going to be around 600 watts rms, that how much it can handle all day long, as long as you got the gains set right. so pretty much match a sub and amp combo w/ the rms wattage.

 

[Ormist 10+ year member]

Hmmm, the gains?

 

[stones 10+ year member]

Hmmm, the gains?

Setting the gain/sensitivity on an amplifier is like an old lady setting the gain/sensitivity on her hearing aid, if its to low she will barely hear anything if its to high it will hurt her eardrums (speakers).

 

[Ormist 10+ year member]

Oh, ok. Thanks alot for your replies

 

[SAG3 5,000+ posts]

and its not just for subs like stated above by stalephotograph

 

[stalephotograph 10+ year member]

and its not just for subs like stated above by stalephotograph

yea i meant to put all speakers, but i just had subs on the brain. sorry man.

 

[germanyt 10+ year member]

in a non car audio electrical system, RMS is 70.7 percent of peak. on an oscope, if a sine wave peaked at 10 volts, RMS would be 7.07 volts. its simply a term in car audio meaning continuous power(what you amp is actually putting out or what your subs can safely handle continuously). kind of like capacitors. on a circuit card, capacitors are generally between 10 and 500 micro farad. as you go up, the cap gets bigger. a true 1 farad capacitor would be teh size of a fire hydrant and a 20 would be the size of a dump truck. my two cents

 

[goodsound 10+ year member]

RMS power is not simply 70.7% of max or continuous power.

RMS power is the product of 'RMS voltage' and 'RMS current'.

And RMS voltage and current are indeed 70.7% of their max values.

And this applies to ANY electrical system, car or non-car, audio or non-audio!

Your trusty $50 DMM does not measure RMS voltage and current. It measures peak or most likely average, which is different from RMS, and even that is accurate only within a very small range of frequencies (typically upto 400hz or 1000hz). Thats why true-rms voltmeters that work in a wide frquency range are expensive.

Continuous power of an amp is the power it can deliver continuously without clipping.

Continuous power of speakers is the power they can handle continuously without getting toast.

Peak power is the power your amp can deliver (or your speakers can handle) for very small period of time (milliseconds) like a loud piano key or drum etc.. spikes which are typically +9db to +12db from your set volume level.

Now you have to be careful what the manufacturer has listed for continuous and peak power . Is it RMS or non-rms ? If they have not specifically listed RMS then simply reduce the power to half.

 

[JimJ 5,000+ posts]

kind of like capacitors. on a circuit card, capacitors are generally between 10 and 500 micro farad. as you go up, the cap gets bigger. a true 1 farad capacitor would be teh size of a fire hydrant and a 20 would be the size of a dump truck. my two cents

Umm....no.

I don't know what you mean by "true 1F capacitor"...

 

[germanyt 10+ year member]

RMS power is not simply 70.7% of max or continuous power.RMS power is the product of 'RMS voltage' and 'RMS current'.

And RMS voltage and current are indeed 70.7% of their max values.

And this applies to ANY electrical system, car or non-car, audio or non-audio!

while the first is true, i would like someone to explain to me how in infinity kappa perfect 12 has a 1400 peak power and 350 rms and can say that that is 70.7 percent. this is what i meant when i was talking about car audio.

and a 1 farad cap for car audio is not really 1 farad. its just easier to say 1 farad than to label it in micro farads. trust me i know my capacitors. im an electronics warfare technician in the us navy which makes me a certified electronics technician in the civilian sector.

 

[JimJ 5,000+ posts]

I'd like to see proof that capacitors sold for 12VDC use aren't really a farad. Especially when I can go to swap meets and buy industrial surplus capacitors that are clealy labelled "1 Farad" and they're much smaller than a fire hydrant //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif Or are they lying?

 

[goodsound 10+ year member]

while the first is true, i would like someone to explain to me how in infinity kappa perfect 12 has a 1400 peak power and 350 rms and can say that that is 70.7 percent. this is what i meant when i was talking about car audio.

I think you are caught between two peaks //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

Its not your fault. If it were in my hands (or any other part of the body for the matter of fact) I would ban the use of specs like peak, PMPO, music power, etc..

The 1400W peak is the max the driver can handle. The 'peak' you are thinking (that is 1.414 times RMS) is simply the power derived from the max value of the voltage and current. Lemme 'splain..

Lets run some numbers.

For this driver, 350Wrms into 4ohms would mean 37.4Vrms and 9.35 Amps rms. So the max values would be 52.9 Volts and 13.22 Amps. So P=VxI=700W. Think of this as just the 'electrical peak equivalent' of the RMS watts specified. It has nothing to do with the 1400W peak spec.

What the 1400W spec is saying is that 1400W is the absolute max that the driver can take. Now here comes the confusion I was referring to in my previous post. We dont know if this is RMS or not. If this is RMS(doubt it) it means that 1400Wrms is what the driver can handle, and if it is max(quite likely) then it means that 700Wrms is what the driver can handle.

Keep in mind that this is what the driver can handle in a very short period of time. This 'short period of time' is nowhere defined or standardised. So manufacturers screw it left and right anyway they want.

and a 1 farad cap for car audio is not really 1 farad. its just easier to say 1 farad than to label it in micro farads. trust me i know my capacitors. im an electronics warfare technician in the us navy which makes me a certified electronics technician in the civilian sector.

are you saying the 1 farad caps are not really 1,000,000 microfarads ? If not then what value really are they ? Cap technology has come a long way. Electrolytic caps can pack a lot farads in a small package! Especially when the working voltage is just 14V.

 

[InhumanAcura 5,000+ posts]

this thread is teh funny

 

[goodsound 10+ year member]

did I say someting stupid...again ? //content.invisioncic.com/y282845/emoticons/silly.gif.3549b64aaa5b6729eb8e865319a3234f.gif