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Post by rock on Mar 18, 2024 4:05:51 GMT
Your project looks great! Thanks for checking in.
As I see your open framing photo, I'm reminded that we don't talk much about wiring here so I'll just mention: If you can, keep lights on separate circuits from audio power and make all ckts home runs from the load center including earth grounds. In other words, don't daisy chain grounds. If you need one circuit to terminate to several outlets, use star grounding. If you contract out the electric, seek out a contractor that does electrical noise sensitive audio installations.
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Post by rock on Feb 15, 2024 21:21:14 GMT
For your purpose I think regular "fluffy" fiberglass insulation will be fine. If you use foam, it should be open cell not closed cell. Simple test, if you can blow through it, it's open cell. The closed cell tends to reflect sound rather than absorb.
You are very welcome and good luck!
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Post by rock on Feb 13, 2024 22:59:32 GMT
Ralf, welcome back to the forum, Your application is a little unusual for this forum but I'll share my thoughts even though I've never built anything like this. I checked the room mode calculator here: amcoustics.com/tools/amroc?l=1600&w=800&h=600&r60=0.6A couple of the calculations are for coverage area: 208 and 173 m2 but that's for a music studio, I think you'll get away with less. If you start with the walls, you've got a perimeter of 48 linear meters. Alternating panels you'll only need to cover 24 meters in total length. You just need to figure the size of your panels to see how many you need to go all the way around. Rigid fiberglass or rockwool are good choices. The material often comes in 2ft x 4ft size in the US. If you use that size or something like it, you can try alternating the orientation as you go. If you orient them all vertically you'll use more, horizontally less. I think you'll need to experiment to see just how much you need. I didn't even mention the ceiling so see if you can improve the sound enough with the walls. The absorber panels on walls will be most effective at ear level. Alternating them so each panel opposes a bare wall area is a typical pattern I've seen in similar installations. I think you're right that you can get away with 2 to 3 cm thick material. If you're building your own panels, you can double up the thickness if you find you think they should absorb lower freqs but it seems not likely. If you don't get any better suggestions (I hope you do), I'd say go at it incrementally and keep and keep going until you're pleased with the sound or you run out of money:) Cheers, Rock
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Post by rock on Dec 17, 2023 17:30:06 GMT
I re-read your last post and I didn't really answer your question about the cloud. (to be placed centered on the reflective paths between the speakers and the listening position). The size depends on the distance between the speakers and the LP. You really have two paths, one for each speaker so if you use one big cloud, it will cover both so that's how you determine the size (bigger is better).
Removing the DW to place the cloud flush with the existing ceiling is good. Again, the distance between the speakers and paths will help to determine the size. The main purpose for the cloud is to absorb the first reflection but it will also do double duty to null the room mode in the vertical axis as long as the thickness is enough (over 8", but thicker is better).
I don't think of openings in the front wall and the ceiling combining as they will each work for modal frequencies in their respective axes. (Technically they will combine when we consider the tangential and oblique modes but they are less dominant so I mostly ignore them and when you think about it, when you reduce the axials with bass traps, you're also reducing the other modes so yeah, I guess they do combine in a way. But then doesn't everything you do to the room combine to affect the whole?)
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Post by rock on Dec 15, 2023 23:33:59 GMT
If I understand you correctly, I don't think it works that way.
Here's the way I think it works: For example, If you take down half the wall (to expose a deeper room behind), you'll still have a shorter length on one side and a longer length on the other side, each with it's own room mode frequency. So you still have some sound bouncing back and forth between the short wall space too. If you want a lower room mode in a given axis, you need to remove the entire wall. If you can't remove it all, you'll get some benefit as you'll lessen the total strength of the shorter mode (depending on where you stand or measure). This is one problem with complex rooms with more than 3 axes; that is calculating room modes.
It's not like water (in the room) that flows through a pipe (your opening in the wall) to fill a larger tank on the other side of the wall.
Regarding insulation, try searching threads here about it, there are differences but with thickness over 8", it seems that cheaper lower density "fluffy" will work as good as the higher density rigid. The physical problem with large volumes (vertical stacks) of fluffy is that it needs support to keep it from compressing itself under it's own weight. You can use wires or screen/chickenwire/hardware cloth etc.
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Post by rock on Dec 14, 2023 14:18:46 GMT
"but the open attic spaces beyond the front wall and the ceiling are huge. They are actually the same space. The attic that surrounds this room is large and open."
The modal response is determined by the solid, reflective walls so removing the inner walls will give you a different, larger room with lower frequency fundamental room modes (that's good).
"I just know that if the drywall was removed (like is said in the linked thread) you must have something that supports the insulation but also is acoustically transparent."
You don't need to make the entire thing transparent. You can use a 2x4 framework (on 24" centers is probably close enough) to support your insulation. It's true that the 2x4s will reflect some very high freqs, but not much. Use rigid insulation if possible but chicken wire or hardware cloth is ok too if you need it in between.
"Totally agree that I don’t wish to over damp the room."
I don't think I said you shouldn't completely damp reflections. I said if you do, you can add more life with reflective materials. The advantage of this is that the complete damping gives you a "blank canvas" to work from with the idea that wood slats or diffusors will not create low freq room modes.
"how deep the insulation should be."
As deep as you can afford. 8" min but up to 2 feet (or more?) if you have the space and deep pockets:)
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Post by rock on Dec 12, 2023 14:27:25 GMT
Hi ferro,
You have a lot of questions here. I know I'm not addressing all of them. Maybe a diagram or drawing would help (I'm not sure what your plans are for the "pass thru"?). And just personally, feet/inches or decimal feet is a little easier for me to digest... but maybe that's just me.
#1. Your room modes are the distance between solid (massive) walls not the porous surface. So in cases where you can open up a ceiling or wall for insulation, you need to measure your "new" room size from the boundary behind the insulation. But yes, it's OK to do that (bigger rooms have lower modes which are generally less of a problem if they are low enough) but you need to recalculate your room for volume and modes etc. You should strongly consider fire retardant material especially for large areas.
#2. The "Magic" room ratios are nice. They are chosen for having room modes spaced apart and not piling up, but with tons of absorber thickness and area coverage, it reduces the reliance on room ratios alone because absorption will minimize room modes.
#3. If you do go with tons of built in absorbers, you may have a rather dead room. I think that can be good for a band room and recording but some people prefer a more "natural" room sound. After and in front all that insulation, you can add a little "life" with reflective materials like wood slats installed spaced along the walls or even diffusors ($$$).
I think you've got questions I didn't address so please feel free ask.
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Post by rock on Dec 8, 2023 14:15:32 GMT
Ethan, you are welcome and thanks for this forum, I've learned quite a bit more than I expected since I first found all your site and forums; Thank You! Ferro, regarding using portable devices: I just looked to see if there is an REW version for Android or iOS and apparently there is not. I found this thread www.audiosciencereview.com/forum/index.php?threads/rew-like-app-for-mobile-android-ios.37151/ It looks like "House Curve" might be a possible substitute for REW, at least for getting basic SPL plots. It uses the internal mic and and may not have the sophistication of REW but for ease of use and portability, it could be useful, I should check it out.
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Post by rock on Dec 6, 2023 14:05:38 GMT
I agree with you about seeing measurements but I also believe as Ethan says that you can do it without. That said, I think somewhere in between extensive reliance on REW and not measuring at all there is a reasonable balance. I suggest you give REW a try yourself. I think like any software there's a learning curve and once you get some level of comfort, you'll find it useful and not that daunting. Just to get started taking measurements, you don't even need a calibrated mic. The idea is to "try before you by". Of course when you get comfortable with taking and reading measurements you'll probably want to get a measurement mic but that can wait. Reaching out is a good idea and you'll find discussions here too.
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Post by rock on Dec 5, 2023 22:57:49 GMT
You're right, it looks better with the 122.5 width sorry; operator error:(
I was not that concerned so much with the angled walls but you are correct that splayed/angled walls create a complex series of modes that are considered difficult to predict...at least that's what I read somewhere.
Yeah, leaving part of the wall at 18.66 still gives you that part creating a mode freq you would like to avoid. But even with the whole back wall at 23.92' you'll still need significant amounts of treatment. The back wall may not be the worst offender but it still might be a good place for absorption. There are plenty of threads on this site; you can check them out to see what others have done. One thing to consider is to find your speaker and listening position first then treat the areas for reflections on the ceiling and side walls. REW measurements can indicate what freqs need attention.
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Post by rock on Dec 4, 2023 23:29:21 GMT
I've simplified your question to simply choose the length of either 18.66' or 23.92'. 18.66 feet is very close to twice the width, that's bad because room modes will pile up, so 23.92 is better because it distributes the axial room modes better. It's not the best room dims but if that's the only choice, that's what I'd go with. You still need lots of treatment but all small rooms do. I used this room mode calculator amcoustics.com/tools/amroc?l=23.92&w=9.375&h=8.875&ft=true&r60=0.6Cheers
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Post by rock on Nov 11, 2023 19:16:42 GMT
Cool, sounds like a plan! I looked up that 4mm is equivalent to 12 AWG (American Wire Gauge... we've got different numbers for just about everything over here:)
Depending on the connectors you have, your 4mm/12Ga wire might be a little tricky to work with but nobody can say your wire is too small!
Cheers!
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Post by rock on Nov 9, 2023 19:03:01 GMT
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Post by rock on Nov 9, 2023 14:13:24 GMT
I'm a little confused on exactly how you plan on separating the amp and speakers in your combo. You were not really very clear on how you were planing to separate the amp and speakers. Are you removing the amp from the cab and keeping the speakers in the cab and moving that into the the other room? If so, I think it's a good idea to slap together a little enclosure for the amp section for easy handling. Re-installing the speakers in another cab sounds to me like a bigger project. One way or another, of course either can be done.
Moving the speakers to another room sounds like a good idea and should work fine. It's a fairly short run but I'd use 14 or 12Ga. cable. The main reason I suggest heavier gauge is because of improved speaker damping rather than power handling. Regular lamp zip cord will work fine but for the heavier gauge, you might find that in outdoor low voltage cable. I don't think you need to buy fancy overpriced speaker cable. (But IMHO there's nothing wrong with it except it's too expensive, so use it if you have a length lying around:)
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Post by rock on Sept 27, 2023 0:30:11 GMT
+/- 4dB is good but in the low you really want the "truth" so don't use any smoothing down there. The one thing that stands out is the peak and modal ringing at about 70Hz which may be a ceiling to floor mode. So if it's the ceiling/floor, adding a cloud or more or deeper/thicker clouds should help. At least 4" but 6" to 8" is better plus use gapping up to equal absorber thickness...but I think you know that, right? The same but to a lesser degree with the other modes. I would not be worried about the lack of symmetry in the low end.
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