Perception and Watts: Doubling of power


There's a curious rule of thumb, which to my ears seems mostly true:

  • To double the perceived volume, you must output 10x more power.

10x power = 10 dB by the way.  We've read this as we were buying amps and trying to decide between 100w/channel and 150w/channel.  We are told, repeatedly that 50 W difference isn't really that much.

On more than one occasion I've tested this and found it's pretty much spot on.  Here's my question:

How can any of us really tell what half as loud, or twice as loud is?

I mean, think about this for a bit.  I cannot tell half as bright, or twice as bright, but it seems I actually CAN tell what half as loud is.  How does this even begin to work in the ear/brain mechanism?? 😁

erik_squires

Playing loud and watts seldom comes into the picture in… well non-low end systems (ok, maybe for college parties). Unless there is a gross mismatch in sensitivity and power.

More power tends to add weight and realism to the sound you get… it fills it out more than making it louder.

I have Audio Research Ref160 monoblocks, they can be run in linear (140wpc) or in triode mode (70 wpc)… there is no obvious difference in volume what so ever. I was actually surprised… I was listening for solidity, but thought I would hear a difference. The only difference I heard was in the ultra linear mode the treble became a bit hard and some of the midrange bloom dried up. I operate them in the triode mode, and they can play at deafening sound levels… (a dealer came over to listen and cranked them… wow, that was loud).

In solid state amps the power directly transforms itself into slam… that is one of the reasons high power ss amps are prized.

I only feel like I have scratched the surface. We’ll see if anyone wants to continue.

@ghdprentice 

 

Good ear. Triod is much better on my canary monoblocks as well exactly the difference  you found with you audio reseach  

First you have to understand there are quality 100 watts of power and there are garbage 100 watts of power. If all you are concerned about is the decibels or loudness of the music come over to my house and I will hook my Sansui 7070 and the Bose 901’s sitting in their original boxes. It will play so loud your ears will ring for days and it will sound like garbage. Then I will play my 80 watt monos into my Vandersteen’s and not only will they play loud but it will sound beautiful to boot. They did not name the company first watt as a gimmick.

@johnnycamp5 Perhaps because it has been repeatedly proven in human testing that an increase in DB (loudness) is perceived as music “sounding better”

I can’t count how many times I’ve read or heard people erroneously claim that a more powerful amp sounds better. If that were true, a 300b "flea watt" amp would sound terrible.

Lots of interesting discussion here, of course, but I really did just want to ask, how can we tell what twice as loud is?  I mean, I think I can, and it happens to match 10 dB.  WHY?  Our visual systems however seem very good at seeing twice the length or half the length, or finding the mid point on a line. Kind of weird that we also have a sense for half or twice as loud.