lars
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Post by lars on Oct 31, 2019 21:45:02 GMT
Hi! Lars from Oslo here. I am going to treat my living room to make it better for producing and mixing. Attached room plan where I am intending to place absorption panels (coloured blue). Not ideal placement of speakers and listening position but this is what I have to play with. Big bookshelf in the back with records and gear, and the slanted things are synths. For all panels I'm planning to use 3.5 inch mineral wool with a density around 75kg/m3. (between 703 and 705 i guess). I just did some Room EQ sweeps and will post mdats. What are your initial thoughts and questions?
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lars
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Posts: 13
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Post by lars on Oct 31, 2019 21:52:53 GMT
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Post by Hexspa on Nov 1, 2019 4:18:17 GMT
Hi, Lars and welcome.
I have reservations about your listening position. My approach is to optimize layout before adding treatment. Ultimately, you're fighting nature by selecting that spot and any treatment will be more like putting a band aid on a melanoma as opposed to a comprehensive approach to preventative skin care.
Also, if you can do a quick gander through the forum and to see how we prefer REW data and post 100kB images we will appreciate it.
Thanks.
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lars
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Posts: 13
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Post by lars on Nov 1, 2019 21:57:22 GMT
Thanks Happy to provide a challenge and exited to learn more. Attached image of 20-500Hz. Very interested in more elaboration on the melanoma in acoustic terms. Increased the amount of band aid. Specific thoughts on how to make it work?
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Post by Hexspa on Nov 2, 2019 1:30:37 GMT
I'm afraid it's terminal.
You see the lesions at 65, 75, and 175Hz? Also observe the tumorous growths at 125 and 190Hz. The lump at 32Hz is benign but I'd keep an eye on it.
We have an experimental treatment called Orient Along the Length Because Corners Are Cancer but many people with your condition tend to just get their affairs in order and call it a life.
As an aside, many people have dome and peaked ceilings, L-shaped layouts and cubed dimensions and do everything they can to make it work. Here you have a perfectly rectangular room and have your nose in the corner like someone on time out. Really, you can do your best with thick absorption to balance out the boundaries but it'll be similar to an eagle who believes he's an elephant raising his head and, upon seeing the fowl, thinking, "If only that were me."
Here's the thing: your response has serious flaws. If you absolutely can not move the general area then try to get the most even SPL you can by moving what you can move - speakers, slight desk repositioning, etc. Absorption is primarily for decay and not SPL which, I've found, is handled by positioning.
It's because the trihedral corner is a trifecta of bass build up. On your right - open space. I can't say exactly how thick your treatment will need be but I'd start max and move min. In other words, if you're not using 8" of rigid or 2' of fluffy then you can not expect optimum results. Optimum, of course, given that you are committed to that location.
There's a lot of analysis you can do such as finding the 1/4 wavelength distance of your nulls and 1/2 and 1x of your peaks and emphasizing treatment there or using the aforementioned repositioning to shuffle things around a bit. You can also see if any nulls overlap with any peaks and balance your treatment there so they counteract. Honestly, this is a bit more advanced so if you're not up to the task, just put as much absorption everywhere you can manage and just be satisfied with whatever you get.
But, in truth, if you can put your listening position at the apex of where your couch is, you'll be way better off acoustically. It's just how it goes and there's really no argument about it. As far as I know, besides the dead center, a corner is the second worst place to set up.
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lars
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Post by lars on Nov 2, 2019 14:38:32 GMT
Thanks doc! Lets rip off the band aids and move to root cause then. I moved the listening position so it's 190cm from the window and 160cm from the wall. Then did another frequency sweep. Is this treatable? Left+Right Left, Right, Left+Right Image cropped to much: L = Red R = Green LR = Purple
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Post by Hexspa on Nov 2, 2019 23:35:50 GMT
Much better.
Arrived at these dimensions by finding the wavelength then using 1x and 0.5x for dimensions relating to peaks and 0.25 and 0.75 for dimensions relating to nulls. Exact numbers may vary slightly due to material density and interactions of reflections and modes. You can ignore everything below 63Hz and your lowest null above that in the left speaker, 70Hz, is balanced by the peak in your right so your sum response is fine. I just put that there to illustrate that this is something worth keeping in mind when trying to even your SPL.
You can try fine-tuning placement or start putting treatment where those dimensions are - obviously if the 50cm is from your desk then you're stuck with it. It could also be from the wall behind your speakers in which case you should try treating there if you weren't already planning to. EDIT: I see that you were indeed planning to. I should mention, which leads into the next point, is that adding treatment has unforseen consequences to your SPL. Usually they're good surprises but, like mixing a song, things can sometimes appear worse before they get better. This is because you're removing the big layer of 'dirt' which just reveals more flaws. That's fine.
The last thing you can do, if this doesn't give satisfactory results, is to then figure out how your dimensions are giving you either peaks or nulls at your listening position then balancing the amount of treatment you place there. In other words, if your ceiling is 8' and your head is right in the middle, you'll probably get a peak around 140Hz; which you nearly do. To balance that, you'd need a boundary at either 2' or 6' - as an example. Again, either that or move your head up or down via chair or whatnot. Positioning, boundaries and their interaction = SPL.
I find it interesting that some boundary around 140-150cm seems to be giving you both your primary peak and null. I'd really try to sort that out first. I see you mentioned 160cm "from the wall" - I assume you mean front wall. That's about a 4" difference so check that out.
You should consider going to 8" of rigid.
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lars
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Post by lars on Nov 3, 2019 17:04:40 GMT
Thank you so much for the analysis! Based on your math I've highlighted the dimensions ( I think) you call out: Given these here are my initial deductions: -Treat the back wall ca 370cm behind me. -Treat the ceiling 160cm above me -Treat the wall 150cm in front of me -Fill the desk with junk aka gear 50cm in front of me? I dont quite understand the 140/280 though. Could be the concrete beam above me acting up? There is actually another vertical concrete pillar 280cm to right of the listening position, only 40 by 30 cm though. Started sketching some panels (in blue). -Curious about them all but mostly about the sides. Im thinking angled side panels on wheels for easy stove away and adaptability. -The cloud could be lowered 20cm from the ceiling How does the sketches look in order to mitigate the findings? When you say rigid. How rigid? Im eyeballing mineral wool at 75kg/m3 or 115kg/m3. Would you add any other layers on top of the mineral wool or just go with 8" for all panels? Again, very appreciative of your feedback. Best Lars Attachments:
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Post by Hexspa on Nov 3, 2019 22:36:42 GMT
Re: 140/280, I think it's obvious that 190, 160, and 150cm are all interacting here. Remember, I said that exact dimensions will vary a bit and that 10cm qualifies as "a bit". More stuff on your desk probably won't help. If anything, put some absorption on and/or under it. Go with the more dense mineral wool, in most cases. Any panel at first reflection points does not get any FRK layers. So, you probably want to go unfaced. Be careful with your gapping like 'lowering the cloud 20cm' as these decisions are not acoustically arbitrary. Bear in mind that you may need to slightly alter your initial placements, based on your successive measurements.
I realize that I just said 10cm is 'a bit' but there's a difference between gapping panels and correlating peaks and nulls with physical boundaries. My explanation is that the panel is a known but the way all your boundaries, their materials and other reflections interact is very complex and we get 'close enough' by targeting the general area rather than the specific centimeter where the boundary 'should' be. At least, that's how I currently approach it. Keep in mind that you still have ringing to deal with. Consider putting absorbers in corners throughout the room to mitigate that. Panels placed parallel or angled to the walls and ceiling, preferably with a 1x or tapered gap, will help. You can put them anywhere but the same principles of wavelength, dimensions and balance still apply.
We could all tune our rooms till the cows come home so it's really a matter of with what will you be satisfied.
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lars
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Post by lars on Nov 5, 2019 21:22:13 GMT
Got it, thanks!
Going to start constructing the sketched panels with 18cm mineral wool with about 75kg/m3 density (halfway between 703 and 705).
Will return with results.
Do share your room and setup as well for inspo if you want.
Best Lars
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Post by Hexspa on Nov 6, 2019 0:42:58 GMT
It's on the forum under 'new room, new problems' or something. There've been a number of good rooms on here. Good luck.
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lars
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Posts: 13
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Post by lars on Dec 1, 2019 18:58:09 GMT
Ah yes. The sonic adventure continues. Today we installed the first panel, the cloud. Its 180 x 120 cm of 19cm thick medium density mineral wool (75kg/m3) hanging 28 cm from the ceiling. Just did another sweep that looks like this: Attaching the previous, before cloud panel, as well for quick reference: What can you read from this? Attachments:
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Post by Hexspa on Dec 2, 2019 2:53:19 GMT
Looks good. Keep going.
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lars
New Member
Posts: 13
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Post by lars on Feb 21, 2020 18:09:54 GMT
Fresh from the workshop! Old man helped med build these 10kg 19cm thick slabs of 75kg/m3. Loving the new details Im getting in my tracks. Cant attach so linking to files: New side panels
New read out from EQ wizard
View from behind listening positionWhat can you deduct from comparing with the last measurement? Im quite happy with the results now, but if you where to do one or two more things (famous last words) where would you focus your effort next? Best Lars
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Post by Hexspa on Feb 23, 2020 16:48:49 GMT
You're better off in some areas but still have buildup around 220Hz and a pesky persistent null at 150Hz. SPL is great but decay is another thing you're improving so why not upload and compare that as well?
If you're set on that position then you can either add more panels in the room elsewhere, like in the upper corners, or try applying a wide EQ notch to bring down the 220Hz a bit. Maybe you can try small movements with the speakers to see if that null improves. I got a null like that from hanging my cloud too low so it's likely the rear wall or maybe the desk.
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