I may have *over-done* the absorption?

Eskimo

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My room is 17'3" wide, 19'1" deep, and only a max of 7'7" tall (but with 2 unequal sized bulkheads running full-length front to back - 1 12" tall, one 7" tall - denoted as purple shading). It also opens to a ~12'x17' room in the basement at the right rear corner (top right in the picture). MLP is seat #4 in the diagram. (The other #'s 1-4 are the subs)
20210112_floorplan.jpg

Each side wall has ~30 sq. ft of 3" rockwool (Safe & sound) with a 2" air gap behind it.
Rear wall has 30 sq. ft of 6" rockwool (Safe & sound)
The front wall (behind the screen) is lined with the same 3" rockwool.

"How does it sound, Rich?" The room is very...Revealing. I'm hearing subtle details in the music that I've forgotten about.
2-channel gives me an amazingly precise center channel effect to where I keep making sure the center isn't turned on.
My projector isn't here yet, so I haven't tried watching any movies.
The Klipsch's certainly aren't "shouting" at me, even at high volumes.. (Klipsch KLF-20 mains with upgraded crossovers and "MAHL" tweeters which are highly regarded).

Anyway, here's the waterfalls. I've definitely got a big null at 116hz which I'm thinking is likely the 4th order length mode? I can't move the mains any further forward - the front of the baffle is 24" from the front wall.

But, maybe covering some of the side wall absorption with a diffusion panel would be a good idea (not to try and address the null, but just in general)
waterfall20-400.JPGwaterfall-20-20k.JPG
 
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DanDan

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I would need to see the .mdat file, but I know from experience that Zones Without Early Reflection cause great, extreme even, clarity. Many of us roll off the HF to compensate. That big dip in LF is nasty although narrow.
I suspect Front Wall SBIR. Try moving the speakers closer, even touching, the FW. See if the SBIR dip rises in frequency and hopefully gets shallower too.
 

Eskimo

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@DanDan - .mdat attached if you're curious (RR seat is the MLP), but seeing as how it's present in every location I measured, it makes sense that it's SBIR as you suspected, and not a room mode like I first thought. They are about 26" from the back wall which according to the calculations *should* be 129hz, but..

I should be able to move the mains further back. They're 12" deep without being toed in - ~15" toed in (223hz SBIR).

Lowe's stocks 2 different rockwool batts - Safe&Sound 3", and "Comfortbatt" 5.5". Both are fairly low density. Since the 3" Safe&Sound is .96 @ 250hz, I figure that should squash it, so I will buy a pack of the 3" rockwool this weekend, and put it right behind and around the mains & center after moving them back against the wall. (There is a bunch of 3" rockwool back there already, but admittedly, there are some bare spots.)

I had the speaker further away from the front wall because I didn't want the frame for the screen/screen wall to interfere with the sound, and by putting the mains 28" inward from each side wall, it addressed a 4th order width mode at 131hz. But, it seems I'll have to experiment and see. Clearly they'll need to go further outward (towards the side walls) to not have the sound interfered by the framing, but maybe it won't be a big deal. (The frame of the screen is 1x4, as is the supporting structure ('goal posts') behind the screen) - pictures were taken about a foot behind the MLP.
goalposts.jpg20210104_180635.jpg20210110_125716.jpg
 

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DanDan

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Fabulous work. Is that Shop Vac an Active Trap? I recommend David Byrne's American Utopia for the inauguration.
 

Eskimo

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Fabulous work. Is that Shop Vac an Active Trap? I recommend David Byrne's American Utopia for the inauguration.
How better to capture sound than pulling it into a vacuum? :bigsmile::bigsmile: Frequency is changed by the attachments and length of the hose ;)

I'll make a note of that performance! She's already chomping at the bite to watch Hamilton, but my new projector (UB5050) is on backorder until the middle of February :crying: (Ordered on black Friday) and I refuse to watch anything on the 720p unit I borrowed from my buddy just for setup. Besides, we have to finish the room blackout and some other stuff first - it's actually good that we can't watch movies yet, or it'll never get finished!
 

sam_adams

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@DanDan - .mdat attached if you're curious (RR seat is the MLP), but seeing as how it's present in every location I measured, it makes sense that it's SBIR as you suspected, and not a room mode like I first thought. They are about 26" from the back wall which according to the calculations *should* be 129hz, but..

I should be able to move the mains further back. They're 12" deep without being toed in - ~15" toed in (223hz SBIR).

Lowe's stocks 2 different rockwool batts - Safe&Sound 3", and "Comfortbatt" 5.5". Both are fairly low density. Since the 3" Safe&Sound is .96 @ 250hz, I figure that should squash it, so I will buy a pack of the 3" rockwool this weekend, and put it right behind and around the mains & center after moving them back against the wall. (There is a bunch of 3" rockwool back there already, but admittedly, there are some bare spots.)

I had the speaker further away from the front wall because I didn't want the frame for the screen/screen wall to interfere with the sound, and by putting the mains 28" inward from each side wall, it addressed a 4th order width mode at 131hz. But, it seems I'll have to experiment and see. Clearly they'll need to go further outward (towards the side walls) to not have the sound interfered by the framing, but maybe it won't be a big deal. (The frame of the screen is 1x4, as is the supporting structure ('goal posts') behind the screen) - pictures were taken about a foot behind the MLP.
You might consider covering all the surfaces behind the screen, floor, ceiling, and walls, with the rockwool. You may also want to experiment with the placement of any of the panels you have throughout the room to try and reduce the variations in the Topt, T20, and T30 times to try and get them within a +/- 20% range.

38462



38464
 

Eskimo

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Wow, thanks for looking into that!
I've not looked much into those graphs.. More reading for me! I wonder though - does the rear row look any better? That's the MLP, specifically, the right rear seat.
 

Eskimo

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Oops.. Maybe this should be over in the Room Acoustics forum?

Edit: Thanks :)
 
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NBPK402

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On my old HT...I put Roxul r60 on the whole wall behind the screen and covered it with black muslim cloth. It def made a difference in my soundstage and also improved the image quality. SeymourAV also sells a AT material that is blackfor putting directly behind your screen, but I just used the black muslim to cover the Roxul on the wall, and it worked fine.
 

RandyR

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It appears that you are using the speakers grills (areas around the screen with black cloth) as the border for the screen. I am thinking of doing the same but was concerned about light reflection on the cloth vs black velvet. I would like to know how it works when you get your projector fired up. By the way, I really like the way it looks.
 

Eskimo

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On my old HT...I put Roxul r60 on the whole wall behind the screen and covered it with black muslim cloth. It def made a difference in my soundstage and also improved the image quality. SeymourAV also sells a AT material that is blackfor putting directly behind your screen, but I just used the black muslim to cover the Roxul on the wall, and it worked fine.
20210115_215314.jpg

Yeah, it's covered now! SBIR is squashed.
 

Eskimo

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It appears that you are using the speakers grills (areas around the screen with black cloth) as the border for the screen. I am thinking of doing the same but was concerned about light reflection on the cloth vs black velvet. I would like to know how it works when you get your projector fired up. By the way, I really like the way it looks.
I am indeed. The matte black spandex does a good job of absorbing light, but it's no triple black velvet.
I have a temporary projector in place.. I'll skew the image tomorrow with the lens shift and snap a picture so you can see.
Since I'm using the 5050UB zoom to create the 2.40:1 image, there will be some areas of overshoot, but I think it'll be OK.
 

StrokerAce

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My AV System  
Preamp, Processor or Receiver
Denon AVRX3500H
Main Amp
Parasound Hint 6
Additional Amp
Sunfire Cinema Grand 5
Front Speakers
B&W 606 S2
Center Channel Speaker
Polk
That's pretty impressive! Nice job. I won't be able to go that far with my project as my listening/ theater room shares duty as living room and wife will only let me go so far! The more impressed she is with the sound though the longer the leash. So I just got my first really decent system together and plan on doing the room correction and acoustic treatments. Did you go into a program such as REW and already know the jargon and all the concepts and what you were looking at and looking for or does it guide you through it fairly easily? I think you went through GIK to do your room 3D layout. Was that fairly easy? I don't have a lot of experience on either subject and before I lay out the cash to miniDSP I want to know if I'm going to be able to do what I need to do without a college course to get there!
 

Eskimo

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There are many help guides out there for the use of REW, and that's what I used.. I had used REW a little in the last build circa 2009 (but just scratched the surface) , but things were also more difficult then without USB mic's..
I didn't use GIK for anything- the layout is just in Floorplanner, but there are better products to use for sure.
I actually never did any kind of wood projects before starting this new theater room - I kinda hated woodworking, and the extent of my tools were a circ saw and a jig saw. Buying a miter saw helped a TON.
I appreciate the kind words, but really, I'd just rather spend the money on equipment than labor to have someone make it look amazing - for what I have into the subs as an example, I could buy a single capitvator 2400ULF. Or, I DIY it and have 4 times the subs, double the power, and a much smoother overall response (due to the placement of 4 cabinets vs a single).
My lady got a bedroom to use as her own little dressing room / she-studio; I got a theater room. (I win)
 

Eskimo

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It appears that you are using the speakers grills (areas around the screen with black cloth) as the border for the screen. I am thinking of doing the same but was concerned about light reflection on the cloth vs black velvet. I would like to know how it works when you get your projector fired up. By the way, I really like the way it looks.
My 5050UB came in yesterday, so I was able to snap a few photos.
If I zoom back so the image is projected onto the black spandex, you can see it, albeit not well.
20210119_175409.jpg

But, using the 5050UB's "blanking" (masking) feature, you can't see anything. In the above picture, I have the top blanked and the bottom not blanked. The top is perfect.

Long story short, I wouldn't be concerned about using the black spandex in this way.
 
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