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Sorry. When measuring thin sheet goods, a 'mil' is 1/1000 of an inch. So .005 to .010 inch plastic. Think of a disposable drop cloth.

Bryan
 

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Discussion Starter #42 (Edited)
Hi Bryan,

Today i started reinforcing the backwall from behind but i could not manage before removing the front ply. When the front ply was removed i couild not resist taking a new measurement.

First rew graph (blue): upper and lower ply removed from backwall
second graph: (red) only upper ply removed from backwall
(green) backwall untouched

What are your thoughts and recommandations?
 

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Discussion Starter #45
rew graph with blue curves: upper and lower ply removed from backwall
second graph: (red curves) only upper ply removed from backwall
(green curves) backwall untouched, upper and lower ply is not removed
 

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Just shifting problems around pending the room length. Really hard to tell much until we get something solid back there.
 

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Discussion Starter #48 (Edited)
Installed reinforced backwall.

New graph

Blue: starting point
Red: reinforced backwall two layers mdf
Black: one sub behind couch (not listenable!)

I see no improvement with new backwall, as tou can see more above on this page the 24 to 80 Hz region was almost perfect flat without lower backwall removed.

How to move further...? Superchuncks on backwall?
 

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Looks to me like it's a sub position issue - listenable or not, that fixes the big null down low.

500-2k is also much better this way.

The wall is just providing a boundary that's more predictable. It will still need to be treated.
 

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Discussion Starter #50
Ok Bryan,

So what do you recommend, 24" superchuncks in corner of backwall, 8" rockwool covered with plastic (surround speakers ambiance) in middle of backwall?

I can treath the left and right wall corner to ceiling with 1' chunks aswell, good idea or not?

Thanks for your kind help Bryan!
 

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Front corners with chunks and the center of the back wall as thick as you can tolerate. Hold off on the other unless you need it.

Bryan
 

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Discussion Starter #52 (Edited)
Ok, backwall is 3.6m wide, 1.4m high, at 1.4 m the sloped ceiling begins ( wich we already treated by removing the ply, after the removed ply is 8" rockwool covered with plastic) so do i tread the entire lower backwall 3.6 x 1.4 or just, lets say 2m x1.4 m and leave the corners untreated?

Front wall is already treated with 24" superchuncks in corners and entire frontwall is made death as per your recommandations.

If i sit in the backwall corners, i do not feel any bass pressure at all.
 

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I tried a sub directly behind me as well and didn't like it. Everyone says you cannot localize under 80 Hz, but I can tell if a sub is directly behind me. Plotted well, sounded horrible.
 

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turn the level down on the one behind you. Every meter closer you'll gain about 6db. You can also dial down the xover point on it to just be high enough to address the dip.
 

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Discussion Starter #56 (Edited)
I agree, i can localise that sub behind me, even when i turn the volume much lower.
X over is on 80Hz for both subs, i will make a listen with the sub behind me on x-over 50Hz.

I tried with treadment on the backwall (blue curve), 1.5' of rockwool, 1.2m x 1.4m did maka things wurse!
All energy stays at front half of room, if i cross the midlle of the room there is not much pressure. This was before i made treatment and stays with treadment. it must be the type of room sloped ceilings on back and frontwall.

I do not know what to do anymore...

I think my best beth is to turn the volume on the front sub higher, so the 80hz dip is gone (yellow curve on graph) and then eq the peaks (maybe an antimode can do this?) from 50 to 70Hz and 20 to 40Hz.
 

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Discussion Starter #57 (Edited)
Todat i did a quick test with rockwool stacked in backcorners, again no benefit.

blue curve: starting point upper ply removed, lower ply untouced
green curve: no rockwool, upper ply removed, lower ply reinforced
red curve: rockwool in corners

As you can see rockwool in corners gives no benefit
 

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Discussion Starter #58 (Edited)
This curve was with lower ply totaly removed, it sounded much better in the low end, altough there are big dips on other frequencies.

Its getting verry frustrating after all the hard work getting no where.
 

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Discussion Starter #59 (Edited)
Well, today i did some further testing.
I played only with the two Klipsch Palladiums without sub.

It was a relieve, bass was so punchy, articulate.

I then A B'd with and without subwoofer, i can only say Without was so much better!

I think the sub's i am using are no match for the quality of the Palladiums...

Here is a graph of spl 1/24 octaaf with only the fronts:

If i could,bring those peaks at 55 and 100 Hz within 10db that would be a good starting point to move further and start with the blending of the subs...
 

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