How much power for a given speaker?

Arni
10+ year member

Junior Member
I have been asking myself and "experts" in car audio stores this question for years with no logical answer returned to me.

How much power do I need in a amplifier to drive a pair of speakers of X watts.

If I have a speaker pair of 100 watt each speaker, how much power should the amplifier have in order to make appropriate use of the speakers capability to perfom?

All comments and answers are welcome

Arni

 
is that 100 watts rms or 100 watts max??

that amount of power per speaker doesn't matter you can throw 25 watts on a speaker and it'll play... but you should always use the suggest rms that the company suggests for the speaker inorder for it to perform, if not more

 
Well I was just saying this number as sample.

U say "use the suggest rms that the company suggests for the speaker".

My question is, how do I find out what the manufacturer does suggest for a given pair of speakers.

You ask "is that 100 watts rms or 100 watts max?? - what is the difference ? what does the phrase rms mean and what is being meant by max?

PS- those who read this- pls do excuse if these questions sound silly there as some basic but important factors that I still need to learn and this forum appears to be a gold mine for that.

 
usually the company will test a speaker by powering it with a certain amount of watts....

when the speaker is at its best performance w/o over doing it or underdoing it that is the rms.

rms = recommend

Root mean square (rms) is, literally, the square root of the mean of the square of a value. It is a process for calculating an average value for a fluctuating value (such as ac voltage or current.) The term rms power is referred to as the average power. A power amplifier rated as having "200 watts rms power" really puts out 200 watts of continuous sine wave power. or where a speaker is near its best performance..... usually u want to stay w/in this range at least -50 at most about +175 watts

max = how much power a speaker can handle

The maximum instantaneous power produced over short time intervals.

this might help

http://www.eatel.net/~amptech/elecdisc/caraudio.htm

 
You are saying that for a given number of rms watts I should stay within a certain range of rms watts for the speakers.

In the case of 40rms watts per amplifiers channel, around 50 rms watts for speaker will yield good results.

In such a case I choose to get me a 200watt amp. and a pair of speakers, 200 watt each, this will do it? What difference in sound will I notice between a 50 watt amp and 200 watt amp, given that I use the speakers with appropriate number like you explain earlier?

I have been told that there is a difference between same number of watts in cd player amp and a seperate amp. Is this true? - if so, do you know the difference.

Thanks for showing this interest in replying to me, I just have to know how things work:)

 
Originally posted by violator5spd are you referring to speakers or subwoofers?
well it differs i think but i'm saying pretty much for both..... u can over power all that stuff or underpower it but its better to over power and adjust gains..

what u think?

 
well i was just asking because he was talking about 40w speakers, and when i read that post it sounded like you said it's ok to send 50w less than the rms or 175 more? that's true with most subs, but not with speakers, and i know you know that but i dont want him to think he should get a 400w amp for his 40w speakers //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif ...

somebody smell smoke??

 
Originally posted by Arni You are saying that for a given number of rms watts I should stay within a certain range of rms watts for the speakers.

 

In the case of 40rms watts per amplifiers channel, around 50 rms watts for speaker will yield good results.

 

In such a case I choose to get me a 200watt amp. and a pair of speakers, 200 watt each, this will do it? What difference in sound will I notice between a 50 watt amp and 200 watt amp, given that I use the speakers with appropriate number like you explain earlier?

 

I have been told that there is a difference between same number of watts in cd player amp and a seperate amp. Is this true? - if so, do you know the difference.

 

Thanks for showing this interest in replying to me, I just have to know how things work:)
i suggest always buy speakers before you buy amp..

if you want good performance you would most of the time need to get an amp.

most hu's don't put out many watts... usually when a hu says like 45x4 or 65x4 its only referring to the max....... which isn't really reliable so its more like 27x4 or 15x4..... i suggest get an amp...

say u get speakers where max is 200 watts and rms is like 40...... i suggest getting an amp that is closer to the rms than to the max..... so you wound want to get an amp that has like an rms of 40-100 watts...... also the product does depend on what u buy..

for example a kenwood amp isn't the same as an alpine amp

 
Originally posted by violator5spd well i was just asking because he was talking about 40w speakers, and when i read that post it sounded like you said it's ok to send 50w less than the rms or 175 more? that's true with most subs, but not with speakers, and i know you know that but i dont want him to think he should get a 400w amp for his 40w speakers //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif ...

 

somebody smell smoke??
well now a days speakers can refer to either coax's comp's or subs, lol...

but if u got a sub i'd send b/w -50 to +175watts to it...

for a speaker i'd say w/in the rms..... -50 watts to +75

u agree?

 
Originally posted by limitkid7 well now a days speakers can refer to either coax's comp's or subs, lol...

 

but if u got a sub i'd send b/w -50 to +175watts to it...

for a speaker i'd say w/in the rms..... -50 watts to +75

 

u agree?
yes, lol

but i would ask here before you send 175w over the rms, or else we'll be reading posts about "I BLEW MY PERFECT WITH ONLY 475 WATTS WHATS WRONG?!?" but for the most part you're good by sending over the rms, but i dont like when people say you're supposed to send the rms...that's just the maximum amount of power that you can safely supply to a speaker over a long period of time...if a sub is 400rms and you send it 200rms no damage will be done, sure it wont get as loud but nothing bad will happen

 
Originally posted by violator5spd yes, lol

 

but i would ask here before you send 175w over the rms, or else we'll be reading posts about "I BLEW MY PERFECT WITH ONLY 475 WATTS WHATS WRONG?!?" but for the most part you're good by sending over the rms, but i dont like when people say you're supposed to send the rms...that's just the maximum amount of power that you can safely supply to a speaker over a long period of time...if a sub is 400rms and you send it 200rms no damage will be done, sure it wont get as loud but nothing bad will happen
brb gotta get some chicken, lol

 
I think I got it clear now what to look for.

I need to a look at the speakers rms/watts - head for a amp that is -50/150+ from the speakers rms output.

Do you know why x-watt rms in radio/cd player is less powerful compared to same x-watt rms in amp of same power?

What manufacturers are in most favour today by car audio freaks ? Just wondering cause up here we only have JBL, Clarion, Kenwood and MTX. Are those ok?

I know it´s a stupid question, taste is different, but nevertheless, what does one want to go for in amp and in speakers and in subs.

Take care you quys and thanx for your help.

 
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