# Loudness

Discussion in 'Amps and Cabs [BG]' started by Jiro, Jan 19, 2005.

1. ### Jiro

Mar 15, 2004
What property constitutes the loudness of sound?

What would you want to get to efficiently gain more loudness?
I just did a calc and found that from a distance or 3.5 meters away from a 250W speaker vs 40W speaker is only like 8dB!!! thats a huge increase in wattage... hmmm what if i want to double the loudness?!

2. ### coldtrain

Aug 19, 2004
North Conway, NH
10x the power...

3. ### Petebass

Dec 22, 2002
QLD Australia
Your post raised many questions but before I ask them, can you runs us through how you conducted the experiment.

4. ### geshel

Oct 2, 2001
Seattle
I'm impressed. The difference between 250w and 40w is almost exactly 8dB, so that is exactly what you should have measured.

dB = 10 * log (P1 / P2)

5. ### geshel

Oct 2, 2001
Seattle
P.S. The "loudness" of sound is due to pressure -- the pressure variation caused by the compression / decompression of air that is a sound wave.

6. ### Jiro

Mar 15, 2004
Ya it was straight out of my physics text book. There was no experiment involved... it was all theoretical.

7. ### Jiro

Mar 15, 2004
looks like if i want to double my volume from 200W which outputs 99dB... Ill need to increase my wattage to 1687983077600Watts with final output 198.526dB.

Just to use as a reference point. Jet Plane at 30m has a sound level of 140dB. This calculation was done from 3.5 meters away from the source.

8. ### Tim__x

Aug 13, 2002
You don't need that much power, I mean, I've heard of headroom but...

Seriously though, 6-10db sounds twice as loud, just as decibels are logarithmic our hearing is too (approximately).

9. ### Jiro

Mar 15, 2004
ooops! hahaha
"Sound levels of around 200 dB can cause death to humans"

10. ### seanmI'd kill for a Nobel Peace Prize!Supporting Member

Feb 19, 2004
No, to double the volume you need 10x the power. So you replace the 200W amp with a 2000W amp.

11. ### geshel

Oct 2, 2001
Seattle
Right -- 10 dB more sounds roughly "twice as loud" to people. 10dB takes 10x the power.

You get much more "bang for the buck" by

a) finding more efficient speakers, and

b) using more speakers

I'm not saying more power isn't good. But it's not uncommon for there to be 3 or 6 dB difference between the efficiency of bass cabs out there. That means one will be as loud with only half or a quarter of the power. Of course, there are tradeoffs (size/weight, and frequency response). And doubling the number of speakers typically adds about 3dB more efficiency for bass.

12. ### IvanMikePlayer Characters fear me...Supporting Member

Nov 10, 2002
Middletown CT, USA
man, i so want an amp with 1.7 Trillion watts.

Aug 13, 2002