Have you used a frequency/tone CD w/SPL meter ...

Huge changes in bass response depending on small changes in seating position. Less than 12" forward or back affected bass by as much 10db.
Everyone should try it if possible. Cheers,
Spencer

Ditto to Newbee & Sbank's responses. The small differences in listening position will be particularly true in small to mid sized rooms, especially ones where the dimensions reinforce the same frequencies (a cube is the extreme example where the opposing surfaces are equally spaced). The meter was also instructive to me since, for example, my initial views of a flat bass response were really not correct.

I totally agree with everyone's sentiments. I use Room EQ Wizard to generate my test tones and graph the response from my Rat Shack analog spl. I guess if I was really serious I would get a better spl.

Yes, some measurement of frequency response is valuable, but, there is simply no comparison between using a SPL meter with a test disc vs using a spectrum analyser (like a Behringer DEQ2496). The spectrum analyser gives you an immediate indication of any changes (like speaker or listener position). It gives you a much clearer idea of the whole spectrum.

I tested my system and room from 10-300hz by 1hz increments from my listening position and was startled by the results.

Response varied by 15-20db in very narrow ranges (+-10HZ). Just by moving my head 1-2 feet there were huge differences. Nulls all over the place.

I am not sure how to interpret the results, because they varied from place to place.

It also takes a while. 290 readings at 10sec each takes an hour. Moving speakers by trial and error then remeasuring could take some time.

I am told that to do it right you should use 1/3 octave pink noise and a spectrum analyzer.

Ken