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

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

Yes,
I own two Hsu Research TN1220 HO subwoofers with their Model 500A amp with 24db per octave high and low pass x-overs at 51hz. I sit midway, [in the center of my listening room], between the subs, in which one is near the middle of my front wall between my speakers and the other is in the rear of my room near the middle of the rear wall.
My listening room, including the dining room and kitchen due to large open spaces is roughly 23 x 23 x 8.
Using a Rat Shack digital sound level meter, with corrections, and the Hsu Research CD-R with 1/3 octave warble tones and a 100 hz reference:
I have a broad peak of about + 7 db at 16hz! and 20hz,
a -4db dip at 25hz, a -3db dip at 31.5hz, same as the 100hz level at 40hz and 63hz, a -2 db dip at 80hz, and a big + 8 db peak at 50hz.
With both subs along the rear wall I have a broad +7 to +9 db peak at 16 to 25hz, a -3db dip at 31.5hz, same as 100hz at 40hz, a -2db dip at 63hz, a -4 db dip at 80 hz, and still have the +8db peak at 50 hz.
The 50 hz peak surprised me because running the speakers full range without the subs or high pass filter resulted in the same +8 db peak as when using the subs, mains, low pass, and high pass filters all together!
I expected the 50 hz peak to be reduced in level by about 6db by using the latter due to the natural -6db dip at the x-over point using 24 db per octave filters, but it was not reduced at all!
Very strange indeed.

I use a Radio shack analog spl meter with the Rives test response disc. The good thing about that disc is that there are a set of tracks that compensate for any false readings that the Radio shack device may give.

Rob

Kenyonbm...Your results are not unusual. And what a lot of work!!! (Get yourself a Behringer DEQ2496). By the way, did you try repeating the meter measurement several times at the same spot? I bet that some of the veriation is simply the measurement. Low frequency should not vary much over a short distance. High frequency will vary.

Eldartford,

Would you please tell us some more about using the spectrum analyser? What other equipment is required, microphones, sources etc.

Any suggested reading?

Thanks, Ken