Theater Renovation for "thebland" usiing 6 SubMersives and RS20i

Mark Seaton

WBF Technical Expert (Speaker & Acoustics)
May 21, 2010
355
74
435
44
Chicago, IL
www.seatonsound.net
#1
It's been way too long since I have posted here. I recently did some more thorough measurements through a recent prep & calibration of a system using 6 SubMersives and 13 speaker channels driven by an RS20i (one of the first few loaded with Auro 3D processing). I and one of my employees first went through connection, testing, aiming and adjustment of all speakers and subwoofers. This allowed us to identify some issues and have time to address them before the Dirac Live calibration which was done by Carl Huff with myself there to help with final voicing and verifying of the performance.

This theater was one of the early, large room systems I worked on prior to starting Seaton Sound and experience from the first upgrade almost 12 years ago and a few following greatly influenced and set priorities for many of my designs in the years following. I've posted a bunch of info on another forum in pieces, but will be assembling it together here to better show the entire process. The theater was originally laid out and designed by Dennis Erskine. I first came in to upgrade the subwoofers which kept giving up the ghost trying to fill the room, and 12 years later we've kicked it up another notch. :cool:

Here are some teasers to start:





 

Mark Seaton

WBF Technical Expert (Speaker & Acoustics)
May 21, 2010
355
74
435
44
Chicago, IL
www.seatonsound.net
#2
Testing round 1

Edited to add round 1 measurement and further details - 07-17-2015

With some recent discussion and questions I've seen I will be posting a sampling of the 40+ measurements I saved from the day of installation, with likely more than 100 taken, along with the subsequent results from the Dirac calibration of the RS20i which was done by Carl Huff with my input at a later date.

I should preface these measurements explaining that these results were not just dumb luck. 6 years ago (2008) Jeff(thebland) & I were talking about adding a monster sub to augment the original BDeap subwoofers we installed 12 years ago now. These were tremendously efficient above 28Hz, and we were able to push the extension into the 10Hz range using the QSC DSP-30 I had him add to the system. My idea was to use the rear right corner for a subwoofer which would have been similar to the custom unit I built for a Keith Yates project I posted about here:
Devastator-w-Mark.jpg Uber-front.jpg

Before undertaking the construction of such a massive subwoofer, we thought it worth a trip with a SubMersive to test various locations of the room to insure the effort would be worthwhile. Only after seeing the measurements was very clear the rear corner was the WRONG location for a ULF subwoofer as a subwoofer 1/4 the capability could produce the same level from the front wall. In taking a closer look at the construction differences behind the front walls and rear equipment area did we realize that these differences were the likely cause of these unexpected results. Here are the measurements we took long ago with a single SubMersive placed at the rear corner, side wall, front left and front right locations:
thebland-2008testing.jpg

While the blue curve here shows the right rear corner was terribly inefficient in the low teens, it is in fact very smooth and more efficient than the front wall locations from ~17-55Hz. We also can see the cyan & red curves from the front wall is a much more efficient location to drive the room below 20Hz with the left/right locations having complimentary peaks and dips.

To better illustrate the strengths of each location I found a measurement from the installation day of 2 SubMersives at the front middle of the room vs the 2 at the rear right corner driven to the same level. While the rear right corner is obviously an in-efficient location to deliver the deepest frequencies, it is quite efficient at delivering the rest of the range. If you look at the cursors you will see nearly a 10dB advantage in the critical 20-35Hz range.

The yellow curve is the pair front pair, the green curve is the rear pair, driven to the same level:
thebland-front-vs-rear.jpg

The configuration we decided upon for the installation used 4 of our SubMersive HP subwoofers up front with a pair of stacked SubMersive F2 subwoofers at the rear. Both units have the same acoustic performance in different form factors. This means each enclosure produces the same low frequency output. As a very nice validation of the effectiveness and appropriate balance with 4 in front and 2 in the rear, here is the overlay of the rear 2 subwoofers vs the front 4 subwoofers. Each subwoofer is receiving the exact same level signal meaning the front 4 produce double the acoustic output of the rear 2. This is what I measured at the main listening position:
thebland-subs-F-R-start.jpg

Next up will be the blending of the front/rear subwoofers at the main listening area and optimization with the front and rear rows.
 
Last edited:

Mark Seaton

WBF Technical Expert (Speaker & Acoustics)
May 21, 2010
355
74
435
44
Chicago, IL
www.seatonsound.net
#6
Hi Mark. Pretty fancy setup! Congrats. Any update on the project such a measurements?
Given some of the recent discussion I went back and finally added the measurements. Post 2 has the measurements which drove the subwoofer placement and selection.

Hopefully some will find this interesting/useful. More to come!
 

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