# worth building panels?



## RH55 (Jan 6, 2014)

Hi all. I have been lurking here in the acoustics section for a long time and am finally getting ready to install some acoustic treatments. I'm in Ottawa, Canada so can't access all of the oc703 and standard insulations locally.

I will put my questions up front with extra details and context below.

- Will superchunk corner traps and bass traps across the ceiling-soffit boundary help me cancel the bass null in the front of the room, or is that aiming too high?

- I'm going to line the screen wall, side and back walls up to 44" or so with linacoustic (or an available alternative). I can get 1" thick Manson akousti-liner with a 1.5lb density. Is that sufficient or should I keep shopping for 2lb? This type doesn't have the black mat that linacoustic does but has similar absorption stats.

- once the akousti-liner is on side walls, is there any benefit to having thicker panels higher on the wall? I am about to order some canvas prints from an artist. I can get them stretched on frames, or I can build 16" x 24" acoustic panels 2" thick and stretch the canvas over them. Would six 16x24 panels be worth the effort and cost or should i just hang prints. I could also just stick 1" akousti-liner behind the canvas but I know thickness matters.

My room is 21' deep. The screen wall is 12' wide. There is a four foot deep wallbo the left front, then then the left side of the theater is open to a longer finished basement playroom for kids making the back wall around 30+ feet. I recently built a riser that is stuffed with a mix of pink fluffy and safe n sound, with 14 vents cut along the right side and back where it intersects with the wall. The ceilings are under 8' at their highest and under 7' under the large soffit that goes through the middle of the room. See photo.

The front of the room is currently a bass black hole, so I have had to move one of my diy sub's to the back of the room. The other is in front between the center and right tower.

My objectives in treating the room are to tame the bass null in front through trapping and to lower the overall reverb to improve the surround sound.

I've got 7.2 surround. Goldenear Triton 7 fronts, GE SCXL center, paradigm ADP sides and back and two 18" SI sealed diy subs powered by a behringer ep2500.

The tape in the photo marks 44". The smaller frame outline is the size of my prints .


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## bpape (Sep 14, 2006)

Don't worry about the response in the front of the room (assume you mean up by the speakers). You don't sit there so you really don't care about response there. I would be more concerned that your first row is in some pretty big nulls as it appears you're pretty much center front to back in the room where you'll have big length mode problems.


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## RH55 (Jan 6, 2014)

Thanks for responding. 

I may have described the issue poorly. If the subwoofer is placed in the front of the room then its bass can't be heard in either row of seating, or outside the first four feet near the screen (where the soffit starts).This was the case before I had a second row when the front row was back a couple of feet. I once tried removing all of the seating and it still happened.

The photo shows the right speaker, but not the front wall, it sits about 2.5-3' from the front. The riser is about 6'8" deep, so when seated in the front row you're about 12' from the front wall. I just built and carpeted the riser and am now a little panicked to get home and double check those measurements.


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## bpape (Sep 14, 2006)

Are you running the mains full range or cutting them off at 80 by setting the processor to small for them? If they're running full range, easily could be the sub being out of phase with the subs in the GE's


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## RH55 (Jan 6, 2014)

They are running at 80/small. I have the triton7s which don't have sub's but do have passive radiators. I've changed receivers, sub's and speakers over the past few years and have always had this problem. Putting the sub in back has made a huge difference though.

Brian what do you think about the canvas panels above the linacoustic (I just found a local source this morning)? Should I make them acoustic panels or not bothrr


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## bpape (Sep 14, 2006)

I'm not sure it's going to help your bass issues. Need to figure out the WHY you're having the issue before we can determine how to address it.


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## RH55 (Jan 6, 2014)

I was thinking that those panels would be more about improving the overall reverb and surround stage than the bass problem.

I recently bought a minidsp calibrated mic. Are there some tests that I could run to better identify the problem?


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## RH55 (Jan 6, 2014)

In case it helps here are some shotsbof the front of the room, including the ceiling cave formed by the soffit at the front.


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## bpape (Sep 14, 2006)

Sure - it'll help the decay times in the room.


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## RH55 (Jan 6, 2014)

Thanks Brian. I have ordered a roll of linacoustic to deal with decay times and some 3lb rigid fiberglass. (Morinbros in Ottawa, Ontario was my source , for anyone local having trouble finding this stuff).

I am going to run some sweeps with the mic to try and get an idea why I'm not hearing bass from the front of the room. I'll also build some corner traps in the front to smooth out my response.

Dumb question though: could adding one or even two more subs improve the overall bass in the room even if placed in this strange dead spot? A new sub would have to go in the front of the room, but I guess I'm wondering if the over all movement of air would be worth the investment.


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## bpape (Sep 14, 2006)

Well, if it's going to have to go in the front too I suspect you'll have somewhat the same issue. The whole idea of a 2nd sub is to put it elsewhere in the room to smooth response and pressurize the room more evenly.


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## RH55 (Jan 6, 2014)

I would have an 18" sub at the back of the room balancing out the sound. I thought adding a third sub would add to the over all pressurization but wasn't sure. I would have two in front and one in back.


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