Originally Posted by FOH
Beautiful room, so congrats on that regard.
The back row being so, so close to the rear wall is just what it is... a tough situation to address regardless of the tools utilized. Also, you're being offered advice by all the right individuals, so all good there.
From the layman's/enthusiast's DIY perspective, I'd approach this as is being done above; with EQ but with massive and focused LF treatment too. In any space, with the mains/subs flush mounted and up front, this places increased acoustic demands on the importance of the physical characteristics of the rear boundary. Immediately, a brief examining of the rear wall surface, I can see locations under-utilized for treatment. That said, every possible square inch of that rear boundary, including the doors, could and should be utilized for some proper bass trapping.
I realize this is an issue, but how motivated are you to address it? Most draw the line, and deal with issues, however many can not simply move on ...
Is there anyway to move the rear seating forward to accommodate more space for rear wall treatment?
Is there any way to re-locate, or add additional subwoofer sources to the rear wall area?
Are you familiar with the DBA (double bass array) concept, and how it eliminates many of the negative effects associated to the rear wall?
1.) The rear wall is essentially untreated
2.) The row 3 seating is too close to the untreated rear wall
3.) The two flush mounted subs up front exacerbate the issue
Which elements are at play here,.. wrt changes?
Many thanks for your comments..... you are the first to ask some of these new questions, so that's also a good start. Everyone seems to have slightly different approaches, some cheap some expensive. Many others I've spoken to have said don't worry, its a common issue with multiple rows and all 12 seats in my cinema are not always used. I have made some improvements over the last few days and the sound (back wall boom) certainly has improved I must say, please let me explain. The following is assumptions of mine only, no one here has guided me so its only experimental.
After viewing the readings of the three rows I did with the SMS EQ, the front and the back row proved to be the flattest, the middle row had the lowest dip. I assumed if I save the best reading on the SMS (front row) then then EQd with XT32 on my Integra 80.3 maybe I might have something better at the back wall. Well that proved to be correct, it was reduced significantly. The other things I experimented with which I think also helped, I didn't use the centre row at all for XT32 EQ
, I did 5 mic positions at the back row, (infront of the seats away from the wall) and the last four mic positions in the front row. I thought since the readings in the middle row are bad on bass, lets just stay away from it. The other thing I've been experimenting with is just saving the crossovers at where XT32 finds them, this too has really reduced the boom on the back wall. THX says to move them all up to 80Hz, but my experiments has proven that produces more boom on the back wall, so I maybe its ok to not follow THX
and just allow them to remain as XT32 finds them.......
A plan I do have however and I'm interested in your thoughts.... I'm deleting the two 10" Velodynes from up front in the next few weeks as I've ordered four SVS SB13-ULTRA that will line up in front of the stage area. Something will change, hopefully for the better all over the room, what are your thoughts on this FOB?
OK, lets get back to your questions.....
1. I am motivated in addressing it as best I can without pulling the cinema apart and rebuilding it.
2. Impossible to move the rear seating forward, the seats are on risers and built that way to accommodate the seats.
3. There is space to add subs to the rear wall but I thought that was no good, I never hear of anyone doing that, I searched for that many times.
4. I don't know anything about DBA, I will have to goggle it.
5. So my subs up front and enclosed within the stage area is making it worse, correct?
Thanks again for your thoughts, lets see what you come back with..