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Rookie question: The relationship between a headphone SPL rating and the output power of amps?

post #1 of 2
3/3/11 at 10:40pm
Thread Starter 

 

Hello all!

 

If I'm not mistaken, SPL is based on how many decibels a pair of headphones will output if provided 1mW. Where I get confused is when I read about headphone amps providing 10-20mW (or perhaps 100mW) of output power. So if a given headphone had an SPL rating of 105, why is it we are still able to plug in our headphones into such amps when just 1mW could take your head off?

 

I'm a newbie, so appreciate any insights!

 

Thanks! L3000.gif

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post #2 of 2
3/4/11 at 11:47pm
Amps don't always operate at full output power. The volume knob limits the amount of power going into the amp from the source. To get full power, you'd have to turn the knob all the way up and the source would have to feed it the loudest signal it could.

But if you have the volume knob at 20%-30% and are listening to moderate passages of music, you won't be getting the full power of the amp.

Another consideration is that amps usually go non-linear when cranked all the way up. In other words, they distort. So you want something that has plenty of reserve power so you can operate it well within the range where it is linear. That way, if you get to a demanding part of the music, it'll handle it without strain.
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