How loud is one watt?

How loud is one watt?

…that is the big question…or is it really???

Guy on the phone: Hello…is that volksmusi.com? I need a 6000 watt PA for a concert in a school hall…about 250 people.

Volksmusi: Oh, hello thanks for calling! Really ??? Sorry…but how do you know that? How loud do you think  6000 watts is?

Guy:  Loud!…I don’t know…somebody from another pa hire just told me I need at least 5k for a room of that size???

No question that I did not get the job at the time as some other company was throwing around big “watt numbers” even though I was cheaper.

And I have to admit, it’s a little bit of an unfair question to ask and I could not answer it either. After 15 years in sound engineering I could not tell you how loud a watt is. Why is that?

It’s because wattage is not necessarily volume!!! Wattage might tell you how much power a speaker consumes but it does not tell you how loud it is. It’s a little bit like saying: Wow, a 1500 watt hover…that’s loud. And having…I don’t know how many diffent kinds of wattages( sinus, rms , music, music peak and many more) does not really help to understand the whole watt thing either.

But how can we express volume then? We can measure the sound pressure and that’s done in decibel(SPL). SPL stands for sound pressure level. And this is a lot more accurate than watts because it actually tells you how loud something is.

Here just a few examples:

0              db Auditory threshold

40 – 60    db Normal conversation at 1 m

about 100 db Jack hammer at 1 m

130           db Threshold of pain

As a good guide: Every 10 db means about twice as loud

In relation to wattage: To produce about twice the volume (+10dbSPL) with the same PA system you will need 10 times the wattage,that means 10 times the power. Yes, that means that if you have a 5000 PA system and you want to be twice as loud you will need a 50000 watt PA of the same sort.

What I am saying is that you will need an efficient sound system in the first place to be loud enough for 250 or 350 or 10000 people. And a loudspeaker that makes the most out of the watts that you put in. One other really important thing is speaker placement, I mean,  how and where you cluster your bass and top cabs. In an age of controller amps and line array systems it’s not the watts that matter, it’s what you do with them!