WATTS the difference.

[Viperv10]

I am curious to know what the difference in WATTS really means for system performance.

For example a receiver in the same line same manufacture with different watts, lets say for arguements sake 35, 50, 70, 100 all RMS.

All everything else being equal why would you shell out the extra cash for more watts?

Is there a WATTS level at which its not really worth paying for, unless you really really really require it?

Thanks again.

[Juan Cortez]

With the advantage with having more power is that you will know that the amp will not run out of steem to drive the speakers, which can cause distortion and destroy speakers if the amp starts to clip. Alot of people think that if you own a 50 watt amp and a 100 watt amp, that the 100 watt amp with give you double the volume. Doubling the power does not give you double the volume, it will only give you a 3 Db increase in volume which is not much. To get a double increase in volume you need a 10 Db increase. So from a 50 - 60 - 70 watt amps you will get very little increase in volume. 100 watts can pretty much drive most systems out there. If you like things loud a 200 watt amp should be efficent to give you the head room you need so the amp does not start to clip. Like I said it will only give you a 3 Db increase in volume. Another thing that comes into play with power, is the sensitivity of the speakers. If you own speakers from Klipsch you will notice that they have a sensitivty near and into the 100's, you can pretty much get a 30 watt amp to drive those things and they will play fairly loud. For every increase in sensitivity by 3 Db means that you need half the power to dive speakers with a lower sensitivity. For example, if you have a pair of speakers with a 90 Db sensitivty and you have a 100 watt amp, than later you get a new pair of speakers and they have a sensitivity of 93 Db. This means all you need is a 50 watt amp to drive them to the same volume level as the speakers with the 90 Db sensitivity. All in all the benifit with more power is more head room, and a tougher time in making the amp clip.

[Andrew Pratt]

I thought it was 3dB is double the volume but to get there you need 10X the power.

Regardless the more power you have available to you the less likely you're going to clip the amp and damage your speakers. Essentially what happens is that as the volume increases the amp tries to deliver more and more power to the speakers. At some point however the amp will run out of current at which point instead of delivering a nice rounded sine wave to the speakers it sends a "cliped" wave as it can't generate the upper end of the sine wave. What this does is it stops the voice coil moving in the speaker which casues it to overheat and possibly do real damage to the speaker. Also as with most things as you reach the limits of a design you start to get degraded performance so your best bet is to always run your gear well within its normal opperating environment. So what this all means is that if you like to listen to music or movies at a high volume and your speakers are of low to normal efficinecy you're going to need at least 80 clean watts to be safe. Now that brings up another issue in that many manufacturers rate their gear differently and some are far more honest then others. Read this chart and take a look at what some receivers claim vs what they actually measure out at and you'll see what I mean.

[george_k]

I looked up the 3dB/10dB thing in an acoustics book, "Fundamentals of Acoustics" by Kinsler/Frey if anybody is interested.

A 3dB difference in intensity level (SPL) is supposed to be perceived as the smallest perceptible change in loudness while a 9dB (not 10 but close enough) is perceived as twice as loud.

The part I'm not too sure about is how much more amplifier power you need for that 3dB or 10dB change in SPL.

[Viperv10]

NAD has on their site that a 10DB increase would require 10 times the power. I can't confirm this is true but is just what I read.

[Aussie Geoff]

Hi,

The ears perception of volume operates on a logarithmic scale.

Have a look at this link HERE and you will see all sorts of facts.

3db = Double the power (e.g. 10 watts to 20 watts) and is perceived as being a bit louder (you can hear 1dB louder if you try with test tones), Most volume controls operate in 1 or 2 db increments.

10 db = 10 times the power (eg. 10 watts to 100 watts) and is perceived at twice as loud.

Of interest, for those that query why too much amplifier power is never enough:

Symphonic music peak 120 - 137dB
Amplifier rock, 4-6' 120dB
Rock music peak 150dB

So if we take 90 dB for 1W speakers - to get to 100 dB takes 10W, 110 db takes 100W and 120 dB takes 1000W - about right for the low end of "Symphonic music peak" for a live orchestra...

Geoff

[JasBW]

Hi,



Of interest, for those that query why too much amplifier power is never enough:

So if we take 90 dB for 1W speakers - to get to 100 dB takes 10W, 110 db takes 100W and 120 dB takes 1000W - about right for the low end of "Symphonic music peak" for a live orchestra...

Geoff

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Klipschhorns anyone?