I've recently done a few things which have improved the bass response in my HT. The proximate cause of the first improvement was the 3rd death of my Velodyne HGS-15 sub. I decided to let it rest for a while and I got a 2nd Paradigm Servo-15 v2 sub. I like this sub cuz its big (I need a big sub for my big HT), it goes low (for some reason, the Velo couldn't go that low) and it has a built-in servo mechanism that prevents it from being overdriven.
Here are the 2 Digms flanking the Stratus Silver center speaker. The subs are actually quite non-descript. Big black boxes.
Second project was to build and install more bass traps. I was so impressed with the first 4 traps that I thought that 7 should be better than 4.
So I did 3 more 8-foot traps and installed them at the junction between ceiling and wall. The result, as expected, is an incremental improvement which is smaller than the original improvement. While the bass was previously quite tight, it is now even tighter. I refer to the bass of the big drums - kick drum, kettle drum - and the lower octaves of the bass guitar. Obviously, any improvement in music shows up in movies as well, which are generally easier to reproduce.
I thought it would be interesting to show the following frequency response charts (sorry for the bad pictures but you should still get the idea). This first one shows the response with only one subwoofer (crossover at 80 hz), no audyssey correction and no Velo SMS-1 correction. You will notice that there is a big peak at 40 hz and somehow, the whole region from 20 to 32 hz is depressed.
This second chart shows the response with 2 subwoofers, a cut by the SMS-1 at 40 hz (there are actually 2 cuts, including a notch filter at 40 hz) and audyssey room correction. The difference between the 2 charts is like night and day. You may also notice that the curve is not absolutely flat, but this is because Audyssey considers the acoustic character of not just the main listening position but the immediate surrounding area as well (cuz you do 8 mic positions). Another thing you notice is that there seems to be a sub-sonic filter at 20 hz. In practice though, I am pretty sure that the response goes below 20 hz - this is the subsonic bass which you can't hear but which you can feel.
When you listen, the result is pretty impressive. A very tight and accurate bass. An even respose across the bass frequencies.
Next bass project will be tougher. Repair the Velo HGS-15 and integrate it with the 2 Digms. This is actually not easy. I hope I can get it to work.
