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Post by rock on Jul 28, 2016 13:32:36 GMT
Just for fun, regarding pianos and reverb: Did you know you can make a piano into a reverb effect unit? Try this simple experiment: (it's easier on a grand with lid propped up but you can do it on a vertical with knee board removed...it comes off easily usually with a spring clip kinda thing). Simply hold the damper (right) pedal down and get your head as close as you can the the strings and soundboard and SHOUT into the piano then listen. You'll hear your voice sustaining back at you. That's it. The combination of all the strings selectively, sympathetically vibrate at the frequencies and harmonics in YOUR voice. If you have never done this, it's pretty cool. Now if you didn't have a digital, plate or spring reverb, you could place a contact driver on your soundboard and with a mic, pick up the reverb output all in an isolated room. Wire this in your FX loop and there you go! Have fun!
Cheers, Rock
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Post by rock on Jul 28, 2016 12:40:16 GMT
Hi George, First, are you sure the piano is not the source of the reverb? If the dampers are old and the damper felt is hard and "crunchy" or the dampers or pedal are not properly "regulated" (fancy piano tech term for adjusted), it can sound like reverb. No acoustic treatment will adequately fix the problem; you need to hire a piano tech (or buy a new piano:)
From your plan, it sounds like you are focusing all your efforts behind the piano (the soundboard). If you just want to quiet the piano down a bit, this would make sense. But if your problem is too much reverberation in the room, you need to treat all the surfaces in the room somewhat equally. If you don't want to lower the piano loudness, I'd forget about the area behind the piano soundboard altogether; it won't do much anyway. A simple test is to stand in the middle of the room and clap. you can move around and see how the reverb sound changes in different places, this will give you an idea of where the flutter echoes are the most. Parallel facing bare walls are the culprit. Floor to ceiling too.
A carpet or thick rug on the floor will help and is probably the easiest and fastest and possibly cheapest. If you use an area rug, consider a felt pad under the rug. Carpeted floors always have a pad but you can specify felt instead of foam if the installation is new. After the rug, if the room is empty except for the piano, (other furnishings like upholstered chairs will help), and still has reverb and flutter echoes, hang absorbers on the walls, alternating on opposing walls will do the trick, spacing panels off the wall (equal to the thickness of the panel i.e. 2" to 4") will allow the panels to work at lower frequencies but your main problem is mid to high. 2" thick panels are adequate but 4" thick will also provide, more LF absorption to reduce room modes and ringing, which is not what I think you're hearing but if you have the resources, I think the treatment job will be much more comprehensive.
Cheers, Rock
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Post by rock on Jul 25, 2016 21:24:49 GMT
I doubt most "things" on a shelf will rattle audibly. You can sweep a low frequency sine wave loudly starting at 20 Hz up to 200 Hz to see what buzzes and fix it or more stuff. --Ethan To add anecdotally the that: My band practice/recording space is shared with other family members so there's all kinds of decorations and doo-dads in the room. Every once in a while, I'll hear some "distortion" in a certain range. I usually end up walking/crawling around the room listening for the source while the offending note on my Hammond Clone is held down with a matchbook or the like. One time it was the latch on a humpback chest (you know, the kind a pirate sits on with his Doubloons inside) another time it was Tibetan temple bells. I have found that blue painters masking tape will stop most sympathetic resonances. Cheers, Rock
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Post by rock on Jul 24, 2016 16:50:43 GMT
Hi Steve, Looks like you're gone already but if you do happen to see this, I'm sorry to see you go. I have to say that I am confused about your comment because from this thread, it looks like it was Hexsaps original post but I have to assume I am mistaken considering your apparent disappointment in us as a whole. In any case, here's wishing you all the best!
Cheers, Rock
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Post by rock on Jul 24, 2016 16:32:02 GMT
It was my understanding that the membrane, (paper, plastic or foil) is glued (spray glue) to the rockwool or fiberglass to make it MORE effective at low frequencies. I don't understand the science of how it works but Ethan's test data with OC FRK panels show that it does absorb more LF at the expense of reflecting Mid and high freq (which is not necessarily a bad thing if the absorber is not in the reflection zone).
I don't have the link handy but if you look for it you should be able to find Ethan's test. The way the test was done was with software like REW (Room EQ Wizard, it's free). First measure an empty room as your basis. Next, place absorbers without membranes in the corners, cover as many corners as you can or you can make incremental tests. Next, do the same thing with absorbers with membrane. In your case, if you want to test a spaced membrane VS glued, obviously, you want to test the spaced before you glue on the membrane and then test again with the glued on membrane. Hopefully, your results will prove the glued on membrane works best since if not, you'll have to remove the membrane (which should not really be too bad as I believe you only need a fairly light application of spray glue to hold it in place)
Whew, That's a lot of work but I think that's one way to know for sure. If you do all that testing please share the results with us. On the other hand, from everything Ethan has taught and showed us, I think you can be confident to just glue the membrane on your absorbers. But don't use membrane glued on absorbers at reflection zones (on the sides and ceiling between listening position and speakers).
Cheers, Rock
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Post by rock on Jul 22, 2016 11:18:40 GMT
That looks great. Yeah, do the front wall the same as the back if you can. For recording, it should be fine but depending on where you place stereo speakers (if you do) you may need to address the reflection zones.
Cheers, Rock
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Post by rock on Jul 22, 2016 11:09:03 GMT
For cheap wood, the Home Depot stores in the Chicagoland area sell "cull" lumber for 10% or 20% of the original cost. When I'm in building mode, I stop in whenever I drive past the store and check to see if they have any thing I can use. Many times there is nothing but sometimes you get lucky. In any case, I would not worry to much. Now on the other hand, maybe you can devise an experiment to measure the wobble and it's audio implication?
Cheers, Rock
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Post by rock on Jul 21, 2016 21:12:52 GMT
A discussion physics could be interesting but the simple solution, (if there actually is a problem) obviously is to build a sturdy stand. I built some at a custom height many years ago out of 3/8 and 3/4 plywood scraps. They still work (and don't wobble Cheers, Rock
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Post by rock on Jul 21, 2016 12:49:59 GMT
Hey -m, Was off line for awhile, catching up now. Great video, very clear and detailed, Thanks!
About the 1/4 wavelength of the ceiling mode (any mode fro that matter), yeah, I guess it makes sense to put an absorber horizontal midway between the ceiling and floor but practically, I think it will be in the way. Even though, it might be cool to experiment to see what results you get. Maybe you can borrow saw horses or rig a makeshift stand?
As far as reflection point absorbers on the floor VS ceiling, you will benefit from both or either but usually the ceiling cloud is out of the way and can be thicker and spaced from the ceiling whereas the best you can usually do with the floor is to use a thick pad and rug/carpet. If you can't put holes in the ceilings/walls you are, of course, limited. Maybe you can consult a painter to see what it would cost to patch holes and paint when you move? It might be worth it?
Cheers, Rock
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Post by rock on Jul 14, 2016 0:39:54 GMT
As it turns out, it seems that most of the members on this forum are using Ethan's model of modular absorbers rather than the "built-in" wall you're going after, probably because of the area needed to implement a 2 foot deep wall. There was a guy a few months ago on Ethan's old forum on the music players network (I think?) with a similar idea. My suggestion to you is to search the archives of Ethan's old forum... sorry, I don't have anything else for you right now.
Keep In touch and tell/show us how your project goes.
Good luck, Rock
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Post by rock on Jul 13, 2016 13:12:57 GMT
If you're in the US, you should be able to find stuff like this: www.google.com/search?q=paper+faced+insulation&rlz=1C5CHFA_enUS615US615&espv=2&biw=1241&bih=906&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj2v_r9u_DNAhVFJCYKHRPWC9EQ_AUICCgD#imgrc=l-jI8jneHIZ7QM%3AFor your front wall, Ethan said you could use all paper because it is not a reflection point so you can staple the paper to the frames. If you want to fill the space behind, you can also roll out unfaced insulation on the floor behind the wall... layer upon layer up to the ceiling, sure, the bottom layers will compress but only to a point, if you're worried about that, your can build in some kind of support every few feet or so or suspend them with twine from the ceiling...If you're going to DIY, you have to work with what you've got and experiment and improvise. I don't think anyone does this kind of thing exactly the same way. Here's a link for insulation nails www.google.com/search?q=insulation+nails&rlz=1C5CHFA_enUS615US615&espv=2&biw=1241&bih=906&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj3sLL0wfDNAhWK7SYKHeiSCBgQ_AUIBygCI built a frame like I'm suggesting back in the 80's but it was flush against the existing wall and only 3.5" thick with mineral wool covered with burlap. I didn't know any better. With what I know today, I would do it differently, possibly something like I'm suggesting but I would be experimenting too, but I'd get it to work somehow and I'm sure you'll figure it out too. Cheers Rock
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Post by rock on Jul 13, 2016 3:34:27 GMT
I re-read your initial post and I see you're looking for "Direct Advice" on how to build a false wall. I'm sorry, I can't give you drawn plans etc. but I can say that all you really need is to get the fiberglass across the corners or spaced from the walls and the ceiling. As long as you get it in the right places, how you do it is unimportant acoustically, you can actually throw un-opened bales in the corners and around the room to get significant results. On thing you should do though, is to cover whatever FG you use with "Open" fabric. I should mention that I think treating the entire wall as I mentioned above, is easier than building many 2'x4' frames and hanging each one at a time.
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Post by rock on Jul 12, 2016 21:39:41 GMT
I thought you said you wanted to make a wall of fiberglass. I'm saying to build a wood frame wall to wall ceiling to floor. Just like if you were building a partition wall. Hang your fiberglass in the wall, let the excess thickness hang out the back, (no one will see it because it's inside your false wall). If you want to make it two feet deep, build the frame two feet from the wall. If you want to fill it completely, you can roll out batts and stack them to the ceiling behind the insulation stapled to the the wall to wall frame you built. You can staple fabric on the frame wall to wall, ceiling to floor.
Cheers, Rock
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Post by rock on Jul 12, 2016 11:42:36 GMT
I've always got ideas but they're not always good:) Sounds like you need some way to support whatever kind of batts you use and I think you'll also need something to staple a fabric covering. If you're covering say the entire front or back wall, a wood frame floor to ceiling should keep the batts supported. You probably don't need 2x4s, maybe you can get away with 1x4s. Putting horizontal braces between the studs half way up the wall might be need to help keep the structure from resonating. Look at how Hexspa made his corner super chunks, you probably use wood too.
Cheers, Rock
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Post by rock on Jul 10, 2016 15:47:06 GMT
Hi Adam, I have to admit, but I am unable to completely understand the exact construction of your building and room but if I am to understand that the building is a solid concrete box or at least there are no other tranmission concerns or with flanking etc. except for the framing you have exposed, and all you need to do is to bring that section of the wall up to the same STC of the concrete wall, first determine the STC of the concrete wall. www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=stc+rating+for+poured+concrete+walls www.ncma-br.org/pdfs/5/TEK%2013-01C.pdfThen build your partition using drywall and framing to the same STC. This can be two separated wall sections, each with layers of drywall on only the outsides and the space filled with fluffy insulation. The number of layers and thickness for your STC can be found from building and material pdfs like above. Finally, use a solid core exterior door or one with a stated STC, you might need to use a double door, one on each wall. In the case of the double door, one usually stand open the majority of the time except for when the most transmission isolation is needed. Of course you'll need to use appropriate door sealing techniques. I am not a professional builder but I've done several projects so even though I have ideas and opinions, they are just that. Sorry to say you should not proceed on my suggestions alone but this is one way to approach the project. Lots of us want to DIY this stuff but I think it can be pretty tricky to get the best results without professional advice or help. Cheers, Rock
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