You've finally
purchased those accurate active nearfield monitors you've been
eying for a few months now, ripped open the boxes, and plopped
them right on top of your mixing desk, just like you see them in
the pictures on the magazines. But are you getting the accurate
sound you paid for? Probably not!
The problem with placing nearfields on top of the mixing desk is that sound reflected
from the console will arrive a scant few milliseconds after the direct sound
from the speaker. And this, friends, results in that undesired phenomenon known
as comb filtering - frequencies are either cancelled or boosted, giving your
ear a false impression of the mix. It's great for a phase shifter effect, but
it's not what you want in a control room! Bass response can also be affected
by the acoustic coupling of the speaker with the desk - not unlike the effect
you hear when placing monitors on the floor.
To combat these particular axes of evil, you need to adjust your monitor placement
a bit. By removing the monitors from your mixing desk, placing them a few inches
above and behind the desk (you will need speaker stands to accomplish this),
you'll not only eliminate or greatly reduce the comb filtering problem, you'll
also improve bass response.
The general rule of thumb for nearfields is that they form an equilateral triangle
with the speakers being about 6 feet apart, and your head being the focal point.
Start there, and adjust to taste. Individual manufacturers may have more detail
on placement, so be sure to read the documentation, but this will get you started.