Can signal shaping affect the sweet spot?

I just completed a sealed AV15 build and was disappointed to say the least in the performance I was getting. It fell off the cliff under 30 Hz. Enter the minidsp and things are much, much better after applying the LT. I let Audyssey XT do its thing and according to the measurements, it's much flatter. However, it seems like I'm missing some output down low. I can see the woofer moving a lot, but sometimes I'm not getting the expected feel. This is my first sealed HT sub and I don't know if it's a function of me having to get used to the sound, or can the rooms sweet spot change once you change the subs fr?

Yeah, that be the issue. With the last minidsp settings I applied, Audyssey had it flat to 10 Hz and even though the bass was lacking that sucka was moving! But when I turned Audyssey off, it didn't measure as well, but the bass was much, much better. I think I'll a final fc of 20hz and then apply a high pass at 15-17 and see what that does. Will post measurements later....

No, I mean with rew. It showed flat to 10, albeit at only 75 db. Just didn't sound right with actual content. Quick question: when using the coefficient spreadsheet, what am I supposed to be entering for the corner frequency? Where it starts to drop off, or where I want it to start dropping off? Or am I completely out in left field?

I'm sorry, the one to calculate biquads. Available from minidsp's website and other places as well, I'm sure.

I think I may have dialed it in using a 48db high pass and by adjusting the lt. I've gotten it to a point where it actually measures better with aud off than with it on.

One issue I came across is that of the only 2 places in the room available to place the sub, one had a huge null at 40, and the other has much smaller nulls at 28 and 25. Another wrinkle is that the av was reconed by AE prior to me acquiring it, and they used a different cone. It probably affected the t/s parameters because the rolloff started a lot higher that it showed in winisd.

I still have to test it for any distress at listening volumes because I finished real late last night. Will post both close mic and eq'd responses when I get home.

I think I've pushed the envelope as much as I can. I played the heavy hitters at volumes I normally don't and there was little audible distortion.

My other subs are a SVS PB-10 that I got off CL for $100 and a Velodyne DPS-12. The SVS gave me pretty flat response down to ~17Hz, but couldn't touch the output of this project, even when paired with the Velo.

I'm still confounded by weird in-room response with the nulls at 25 and 19 Hz (I misremembered in my previous post), but it's the lesser of 2 evils. I don't know if it's the nulls that contribute to the shelf at 30 Hz, but even though it's lower there, I have good output down to about 15. I figure I need a second sub to iron out the null, but I've let my brother use the SVS and I can't get the Velo to play nice.

Anyway, here are some graphs. Close mic, EQ'd FR with and without Audyssey, an overlay of all 3, and another overlay with 1/6 smoothing, and the spectrogram for good measure.

Frankly, I'm not sure how. No matter what I try it doesn't seem to change the basic shape of the signal below 30. I can get lower or higher output, but that drop at 30 always remains. Would a shelf help with that? Even if those nulls remain, could it get the portion between the 25 and 19 to increase? Guess trial and error might be the best option.

If all else fails I can leave it as is. Even though it's not flat, I certainly do hear the sub 20 content much stronger than I did with my old setup.

Yeah, it's definitely the room. When I moved the mic out into space, far away from where the LP could be, it was strong and flat down to 15 or so in my room before rolling off.