Help with First Sonosub!

[MDJones]

Yep it is. The smaller the room the greater the gain (up to a point). That's why sealed up cars get such high SPL (cabin gain).

Hmmm, but isn't the size of the room what determines what frequencies are amplified (smaller dimensions = higher frequencies)?

[ThomasW]

Yes it's the interaction of the frequencies with the geometry of the room.

So high output at 16Hz is either room gain, a lower than anticipated port tuning, or bit of both.

If you make a nearfield test (meter 2" from dust cap) that will tell you what the woofer is doing. The meter at the port outlet tells you what the port is doing. If there's not much activity from either of those at 16Hz, then it's the room

[MDJones]

Hope everyone had a good turkey day!

I was in Texas visiting some family for the week, but as soon as I got home I finished rearranging everything and did some calibrating. I now have all my speakers, including the sub, spaced further apart. It sounds so much better; I should have arranged everything like this to begin with! Now that the subwoofer is properly placed, it sounds absolutely INCREDIBLE! I did a preliminary frequency response plot to see what was going on. It is attached below.

The peaks at 36-40 Hz and 80 Hz are what I would expect from room modes (Calculator), but there is a really nasty dip at ~31.5 Hz. I was prepared to use the BFD to equalize until I saw this dip. Not really sure what to do about it. I am also pretty happy that this thing stays strong till at least 16 Hz in room. Even with all this going on, all my demo movies sound great, so I'm not in a big rush to flatten the FR. A great design from Thomas!

[Bent]

MDJones, we haven't heard from you in a while - how are you likeing it now that it's broken in?

[MDJones]

Lol, sorry, I have been busy installing a projector and setting everything up. I just don't seem to have much free time. I moved the sub around a little bit to see if I could get rid of that nasty dip at ~30 Hz, but the frequency response was pretty constant within 2' or so. I have done absolutely no EQ work yet with the BFD, but the sub still sounds pretty good to me.

I watched Constantine last night, and have watched a few other movies with the new sub and projector, and I must say it is a totally different experience. The sub adds a ton of "feeling" to movies. It's much more immersive when you FEEL explosions, gunshots, etc.rather than just hearing them. Scary movies all of a sudden become 10 times scarier. I have already demoed it to a few friends, and they were all in astonishment, especially when I made them put their hands on the drywall and feel it flex :B

I still need to do a lot of fine tuning with the BFD and the new projector. However, I have been simply enjoying what I've done so far. I just hate to get so caught up in tweaking that I don't enjoy the results. Plus, I'm lazy. I might be more inclined to do some EQ'ing when I get my computer setup in the room (to make measuring easier), but even that might be a while. For now, It sounds good enough that any normal person wouldn't think it wasn't perfect. And it just looks slick. I'm happy!