a Power vs Volume Question

Mbacinello, yes it holds true, a watt is a watt.

The confusion is caused by manufactures who state sensitivity in terms of voltage instead of power. It takes 2.83V to produce 1W into 8 ohms. This same voltage produces 2W into a 4 ohm speaker.

This means a 90dB/1W/1m 4 ohm speaker will be a 93dB/2.83V/1m 4 ohm speaker since the voltage spec is actually 93dB/2W/1m. This can can be misleading but the manufacturer will say that since most amplifiers are voltage amps and can produce twice as much power into 4 ohms as they can into 8 ohms they are justified in inflating their sensitivity by 3dB.

To add to the discussion;

1) Each additional speakers gives you 3 db SPL

2) Each time you double the distance you lose 6db SPL ( 2 meter is -6 db, 4 meters is -12db )

3) Line arrays drop at 3 db per meter when are very close to the speaker....as you get into farfield they behave just like other speakers

4) The room will help reduce the loss of the sound level with distance through reverberation.

5) Speaker close to a rear wall add up to 3 db SPL in the bass.

6) Speaker in a corner add up to 6 db SPL to the bass.

If you are serious about audio reproduction then consider this: a drum set can produce 115 db SPL and a symphony orchestra can produce 110 db SPL, marching bands and rock concerts can achieve more.

A drummer sits at the back of the stage. A conductor stands several feet back from the orchestra.

A system that can achieve 105 db spl continuous cleanly at the listening position (with 10 db of head room) is roughly what you need to cover all but the most extreme situations.

He Shadorne; I like that!!

I also read somewhere that you lose 3 dbs output going from a 8 ohm load to a 4 ohm load with the same wattage.

Does adding a powered sub to the mix free up the amp to play at louder volumes,ie: will the amp seem to play louder with the sub in line?