Originally Posted by Skylinestar
upperbass.jpg 137k .jpg file
Attached is the REW frequency response from 60Hz to 350Hz. The sweep was done with subwoofer and the mains together. The variable is the crossover frequency of the mains...adjusted from 80,100,120 & 200Hz to see the effect.
Not shown is the 20-60Hz range, which is good enough for me (variation within 5dB)...thanks to my dual subwoofer setup.
What bothers me is the serious nulls across the mid and upper bass range. What could possibly be the reason? What are the fixes? Simple bass traps?
Apply a little smoothing to this graph and repost. Mains FR is a little easier to interpret with a little smoothing, especially with as many graphs overlaid as you have there. Just from what I can see the 80Hz after Audyssey looks like good starting point. You can adjust the distance setting on your AVR for the subs to tweak delay/phase mains/sub interaction around crossover, see Audyssey FAQ thread for a how to.
In practical HT applications I've found you can't move the speakers far enough away from the front wall to mitigate the front wall bounce, I've found it easier/better to move the speakers as close to the front wall as possible and use 4-6" treatment with 4" air gap behind the acoustic center of the speaker.
What is the published FR of your speakers and and tuning? Try plugging the ports of your speakers, especially if they are tuned close to crossover which would mean considerable port output in that region and re-run Audyssey.
If your running the sweeps all channels stereo, consider running mono for center channel. Center intelligibility is paramount IMO for HT since there are so many channels its next to impossible to get them all flat for one seat let alone more than one.
As stated that region is tough in small room HTs.