I would like to make some graphs of the speaker spl so i can see what I have and what changes in crossovers do for me before i start my Pi cabinets.

this is what i have been trying so far.
run a sine wave tone into my amplifier, adjust the volume control to give me 2.8 volts across the speaker leads, measure the spl from 1 meter away on axis.

Is this even close to being correct?
Is there a better way to get 1 watt into the speakers.
is there a better way or program that can make a graph other than just inputing the spl readings into exell.

any input would be great.

thanks,

bmar