2. misc-audio
  3. 181369-20253

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
secretguy
1,597 posts
 

Most of the info you get here is worth what you pay for it.

gdnrbob
4,417 posts
 

@secretguy 

Good one!.

B

Ag insider logo xs@2x
liamowen
193 posts
 

Turn on your I phone SPL meter and let me know when you get to 140 decibels.

yoyoyaya's avatar
yoyoyaya
623 posts
 

We can easily distinguish changes in loudness but human beings are not SPL meters - our sensory system doesn't work that way in the sense of being able to calibrate what we hear in dB - cue the eleven is one louder sketch in Spinal Tap.

As regards the reference to amplifier power in the OP. I don't think many people look for more powerful amplifiers from the perspective of playing louder. It's more about dynamic range and playing at the desired volume level without distortion.

Speaking of distortion, a low wattage amplifier driven into clipping will sound subjectively louder than a high power amplifier playing at equivalent or lower SPLs.

As another example, modern popular music which has been compressed to hell sounds superficially louder - hence the loudness wars in modern mastering.

So loudness is a bit of an ephemeral concept.

petaluman
140 posts
 

50 W difference isn't really that much - unless the user is pushing the lower powered amp into clipping.  Clipping results in increased high frequency content, harsher sound, and possible damage to speakers and/or amp.

More to discover