Thanks for the explanation highfigh. Very simple and understandable. What would you recommend using to help understand your room response prior to possible EQ'ing? Is that what REW is for?
ANY RTA hardware and/or program/app is helpful, to whatever extent it's accurate, so yes- that's what REW does. It lets us see what's happening and that's a great tool- knowing what we're hearing is harder to define and it saves a lot of time and frustration because treating that one frequency or a range that we think is causing problems will result in failure if we aren't sure that it's what we need to address.
One good example- the low E on a bass guitar has a fundamental frequency of 41.2Hz, but what we "hear" when it's plucked is actually/usually the first harmonic, at 82.4Hz (subject to the player's ability to tune their instrument). Thinking that 41.2 Hz needs to be adjusted, which is often impossible because most equalizers don't have a slider for that exact frequency, has often resulted in blown woofers because the adjustment wasn't sufficient and the slider was boosted too much, and also because the woofer couldn't handle the added excursion. The only time the fundamental frequency will be dominant is if the string is plucked at the mid-point of its length, so the band that would be adjusted for the above example is somewhere near 82Hz, although the room may require some tweaking above or below. Another problem is room modes, also called 'standing waves'. An equalizer isn't the best tool for these- that's why acoustic treatments are used. You can try to reduce a standing wave that's too strong or too weak, but it's a naturally occurring phenomenon, so it's going to do what it wants.
If you use REW or some other RTA program/app and see a deep V in the response, divide that frequency by the speed of sound and you'll find that it coincides with a room dimension, or a multiple of a room dimension- remember, sound energy works in three dimensions, not two. This happens most frequently in the 50-120Hz range and if you move a padded chair into one of the corners, I would almost guarantee that you'll see a difference in the response.
