(I posted this to the tweaks forum to no avail...)
No, I'm not building a room, but the house we're buying has one that will be used for A/V (more A than V). It's not pefect, but I won't waste anyone's time with the things that CAN'T be fixed (while a fireplace is nice, I NEED that end of the room).
The room is in the basement...concrete floors, concrete block, load-bearing walls. 17 x 11 x 6.5 feet. The ceiling is exposed rafters. There's a section of duct-work that runs along the top of one of the side walls for about 5 feet.
First, the walls. It's my impression, based on other posts, that concrete walls AND floor might not be optimal. True? If so, can the problems be mitigates with Jon Risch's acoustic treatments?
Second, the ceiling. For sound insulation, I would guess that I should install fiberglass insulation between the rafters. Then, I would like to finish it in some way. If I can sheetrock it, I will, but I may not be able to. If I need to use some type of tiles, what is best? A drop ceiling seems like a bad idea.
I'll try to encase the duct in some way, and perhaps pack insulation between that encasement and the duct itself, to damp the duct from resonating...opinions?
Believe it or not, I have searched the forums, but haven't seen many comments about block wall...although the ceiling is my primary concern. Thanx in advance.
Thanx to everyone (so far) for their input. Regarding the ceiling...it looks like anything that will lower it is a bad idea. Actually, to be clear, I'd put the bottoms of the rafters at 6-1/2 feet, maybe a little higher...so the main reflective surface is a good 10 inches higher yet. My primary concerns are that the living room is directly above this room, and that the ceiling is ugly. What can I do to insulate the ceiling without lowering it too much? And, what if I were to suspend a very loosely woven fabric from the rafters...something with good acoustic transparency, but that would hide the rafters and insulation?
As to the walls...I'd planned on building some bass traps, anyway. I'll probably constuct some of JR's panels and try that first before I apply drywall or panelling.
I'd already planned to add a good-sized rug and dedicated AC.
Once more, thanx for everyone's input. Please feel free to comment further!!
My basement room is also concrete floor & walls - and a 6.5 ' ceiling.
First - DON'T screw around with the ceiling - it's not optimal, but anything you do will (a) deaden the sound badly and (b) cause further reflections. The open rafters aren't all that bad - they break up and resonances quite well.
Your issues are twofold - first is bass boom and bass reflection, you have nothing absorbing and everything reflecting. If your system has a fairly good amount of bass energy, you will likely get excess bass boom. The traps in corners will help, but not enough. I simply built woof panel walls with wool fibre insulation on 16' centers, being careful to seal them so that the wood would resonate - then the insulation absorb. This was the biggest help in getting very good sound. This also effectively cures the second issue, which is the reflectivity of the concrete - it absorbs nothing and reflects everything. I also put a rug on the floor - thick wool - in front of the speakers to catch the first reflection. Yes, the rigidity of concrete is excellent, but it's reflectivity is not.
Once I did these things, my sound was very good - if not equal to what I would get in a room with plaster/lathe walls and higher cceilings. I think you will find that this makes the ceiling a non-issue, at worst, you will get a bit of a sense of compression or overhang, but nothing to really annoy.
I made a dedicated listening room in my basement with nearly an identical situation. I studded, insulated and sheetrocked the side walls (Wisconsin climate). I didn't want to carpet the floor so I used an acid stain on the concrete floor which turned out very nice. I then covered the floor between my listening space and the speakers with a thick area rug.
I dislike drop ceiling and didn't want to bother with sheetrock so I used the acoustic tile-like material that comes in 6 inch x 4 ft long tongue and groove planks. They have a wood-like grain on the surface and you staple them up to the rafters with a staple gun. The rafters were spaced a little too wide so I had to nail up some 1x2 cheaters (16" on center as I recall) perpendicular to the rafters for the acoustic tile planks. This worked very well. The drawback is that you don't have easy access to the rafters that you would have with a drop ceiling but it would be easy to just pull a couple out and replace them if needed. These planks are a little less reflective than sheetrock (just like the acoustic tiles in a drop ceiling). I did have to frame out a few places for some duct runs.
I then made some Jon Risch corner tube traps and 4 of his wall panels for the side and rear wall 1st reflection points. The room was fairly bright without these treatment devises but with these installed, the acoustic properties of the room are excellent (the best I have ever heard). The room treatments made more improvement in my system than any component upgrade that I have ever made.
I also installed dedicated AC lines for my components. It was a fun project and turned out far better than I would have expected. Here are a few pics although these are kind of old (much better chair now, etc.).
You've got a very difficult room, and your main problem is the ceiling height. 6.5' is pretty low and the duct creates additional problems. A drop sheet rock ceiling is not the way to go here, you'll get too many reflections, at least the open rafters will breakup the sound but you have to deal with the duct. Different types/quantities of insulation affect the sound differently, you'll only know what works after you've installed the system so you can monitor the effects of insulation.
You probably would need to put carpeting on the floor but I wouldn't touch the walls until later, depending on your speakers and the overall balance of the room the concrete walls could even be a good thing. There are many ways to break up sound waves and deal with echo and slap echo. Again the only way to know for sure is only after your system is up and running and all your furniture is in place. You have to hear the problems first.
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