Listening Room Plans?

Discussion in 'Audio Hardware' started by Diver110, Nov 3, 2015.

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  1. mdm08033

    mdm08033 Senior Member

    Poles aren't a problem. Parallel walls, floors and ceilings are your problem.
     
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  2. Black Elk

    Black Elk Music Lover

    Location:
    Bay Area, U.S.A.
    Tremendous first hand experience, Kyhl. Makes me wonder why 705 seems to get mentioned as well as 703 if it is too dense for 'corner stuffing' use. I wonder if 705 is more suitable for making 'shaped' traps, where the 705 panel is a certain distance off the wall?

    Do you know which 'pink fluffy fiberglass' you ended up using? Does it also work as well if rolled and placed in those circular linen clothes hampers (Bongo bags, and similar)?
     
  3. Diver110

    Diver110 Forum Resident Thread Starter

    Location:
    Camas
    Really? Why not? Can I just plant myself, say, next to the pole? I have a pretty big basement, maybe 30' x 50'. What if I finished the whole sucker, put the system on the (not especially) short wall, and the speakers far out into the space, possibly pretty far from any wall? A complication is that toward one corner I have the contols for my wells, and kitty corner across, the washer/dryer. So that stuff obviously cannot be covered up, though it might help break up the sound.
     
  4. Kyhl

    Kyhl On break

    Location:
    Savage
    @Black Elk
    I don't know the source of the idea that 705 was better. My theory is that many see that 703 works so 705 must be better.
    If you look at the measurements on Bob Gold's site it shows that 703 measures better pretty much across the board.

    Also from Bob's measurements 12" of fluffy fiberglass on a wall measure similar to 6" of 703.
    I don't have the ability to measure changes in my room anymore but I would bet that 12" thick cube of fiberglass compressed to hold a pound or two would work better than 6" of 703, as well as working on lower frequencies.
     
  5. Captain Wiggette

    Captain Wiggette Forum Resident

    Location:
    Seattle
    Parallel walls and floors, as in most normal rooms, create very predictable patterns of standing waves between them because of basic physics. If you have a cube, then all those standing waves are exactly the same in all three directions, so the problem worsens. If the dimensions vary, especially in a non geometrical way (say, length is not exactly twice as width, etc), then these standing waves won't pile up on each other all in the same frequencies and places, so the room's response will tend to be smoother.
     
  6. Captain Wiggette

    Captain Wiggette Forum Resident

    Location:
    Seattle
    I will note that soundproofing is very DIFFERENT than room treatment. If you don't have a reason to soundproof, don't, besides the fact that it is very difficult and expensive to do properly. The very best walls for soundproofing are very massive, and things like brick or concrete (ideal for soundproofing) which is WORSE when dealing with acoustics inside the space because bass won't pass through that but reflect back into the room more.

    Making sure that the sound INSIDE the room when you're listening is an entirely different task than preventing that sound from escaping the room. Please don't confuse the two because they can be very much opposed to each other.
     
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  7. bmoregnr

    bmoregnr Forum Rezident

    Location:
    1060 W. Addison
    Good point, and I know nothing about these things, but my read on what Alan Shaw is saying in that post I linked to is this would help with dampening and dealing with the inside space; maybe you are saying that already I am not sure.
     
  8. Diver110

    Diver110 Forum Resident Thread Starter

    Location:
    Camas
    Is there a point where the room is so big that walls cease to have a big impact? My basement is pretty large, perhaps 30x50.
     
  9. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Living in South Florida, we don't have basements but we do have plenty of cement & concrete walls, something that you have in your basement. Your cement basement walls will become the source of deep bass reflection. Deep bass can easily penetrate ordinary wallboard and this is a good thing. If you are going to use something that has a density of 5-lbs per square foot it can be about 6" deep or 12" (or more) if 3-lbs sq ft or less.

    You want to allow the bass to penetrate the dry wall and into the pocket of insulation between drywall and the cement basement wall. Anything low bass that passes through the layer of insulation and reflects off of the cement wall will encounter more absorption as what remains of the original wave is reflected back toward the room. A 6" absorber, becomes a 12" absorber.

    You have the opposite problem for the ceiling, so double up on the insulation there and place a dense material like quiet rock or a cement wallboard under the joists on top of the layer of insulation to prevent bass from coming up through the floor of the room upstairs.

    I would favor a curved front wall, that is how I would build it out. the spaces inside, can be used for storage, equipment racks, etc. When I say curved, I mean curved back to the listening position, a huge semi-circle. You might build an angled partition across the washer & dryer (if that will be used as the back wall. The parallel walls behind the listening position will not matter so much.

    If you get to build out your space, I say, go for it! If someone down the road wants to change the space, they can just tear down the interior walls and make it back into a large rectangle if they wish.

    For better bass control, I prefer front firing subwoofers, ones without the rear ports, rear ports create more problems than they solve. Who wants sound coming out the back. Look at any commercial sub installation, none fire out the rear or the bottom, always from the front. Since you have the room, consider a commercial sub. On of the subs in my room is a Yorkville 15" commercial sub, a UCS1, powered by a Crown XLS-2000 class "D" amp, with the stereo channels summed for mono output.

    I would use two subs in the front, like this one, or cabinets with an 18" bass speaker, cabinets with dual speakers would work extra well. Remember, large cabinets will give you a free, more natural sounding bass and combined with an external power amp, the combination is not expensive. You could add one or two more subs in the rear to smooth out the bass down the road.

    Good Luck!
     
  10. Captain Wiggette

    Captain Wiggette Forum Resident

    Location:
    Seattle
    No, walls always have an impact, but as the room becomes larger then the standing waves become so low in frequency that they are no longer a major concern. Your dimensions are still well within the 'small room' category of acoustics where modal considerations are significant. If you have a symphony hall, modal considerations dissipate, but the walls and their contribution to sound diffusion remain very significant. If you are outside, you have only one boundry (the ground), and the lack of reverberation can actually be undesirable (a wide open field is not a bad approximation of an anechoic chamber), which is why for most outdoor concerts reverberation is added artificially to the sound mix.

    You can plug your room numbers here: http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html

    There are some other articles there that look pretty good, too, though I have not read them.
     
  11. Kyhl

    Kyhl On break

    Location:
    Savage
    @Black Elk and others.

    There is an absorber calculator floating around the web. I have an older version in Excel saved somewhere. You can play around with thicknesses and densities and this will graph the absorption values.

    For Corning 703 use a flow resistance of 16,000, for 705 use 30,000. From Gearslutz.

    At 12" (300mm) , 703 is the same as 705 at 20hz but 703 is better from 20hz to 10kz, using no air gap for all of this.
    At two feet 703 is the clear winner.
    At two feet, assuming 8,000 density using 1.5lbs of fill bests 703 by 25% in the low frequencies.
    Interstingly, 3 feet of 8,000 density is the same as 2 feet thick. If you drop it down in density to 1lb, 5,333 it shows better absorption again.

    The caveat is that I am taking a swag at the resistance of 1lb of fiberglass being 5,333, or 16,000 (value for 703) /3 = 5,333.
     
  12. Black Elk

    Black Elk Music Lover

    Location:
    Bay Area, U.S.A.
    Thanks for the follow up, Kyhl.

    Getting back to the OP's situation: do you have a sketch of the space, location of pillars, size of pillars?
     
  13. varyat

    varyat Forum Resident

    Location:
    wheaton,IL,USA
    May be wise to have a basic drawing of the proposed space and send it off to Vicoustics for an acoustic analysis. Sure, they will recommend their acoustic treatments to tame any reflections and bass nodes. But they will also provide a very detailed 3D drawing of the space which you can use to fine tune your proposed space. Cost is very reasonable for this service , depends on the complexity. You can pay for the drawings and then decide if you want to use their stuff- which is very good btw. I have recently fine-tuned my room with their products with great results- I have some difficult architectural elements that were causing a lot of issues for me.
    I know this idea sounds like you are doing things backwards, but Vicoustics may actually help you optimally design your room and save you a lot of heartache in the end. Just my .02-good luck!
    ATB,
    Mark
     
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  14. Diver110

    Diver110 Forum Resident Thread Starter

    Location:
    Camas
    Thanks for all of the feedback!
     
  15. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Here are a couple of examples of what you could do, without a major investment while you are doing over your basement.

    [​IMG]
    This is what an 18Hz horn really looks like

    Originally posted on What's Best Forum by back in 2010.
    [​IMG]
     
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  16. Tullman

    Tullman Senior Member

    Location:
    Boston MA
    I never thought much about this until I removed the glass table I had. The sound improved after getting rid of the glass table in front of me.
     
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  17. mcbrion

    mcbrion Forum Resident

    Location:
    Connecticut
    AMEN!
     
  18. mcbrion

    mcbrion Forum Resident

    Location:
    Connecticut
    No multiples of other dimensions. When in doubt, read Alton Everest's Master Handbook of Acoustics. 8 x 16 x 24 would be a very poor room, with multiples of fundamentals "hitting" each other. NO, NO, NO!!!
     
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  19. toddrhodes

    toddrhodes Forum Resident

    Location:
    South Bend, IN
    Duly noted, the room is completely empty right now. I measured the other night and if I remember right it's about 15' wide and while it's open in the back left, generally speaking it's about 28' deep. The plan is to sit about 16' back from where the speakers will be (4' from the front wall, so the viewing area will be 20' total). Ceiling is 9' but we'll probably end up at 8' so as not to have a multi-level drop ceiling to accommodate our mechanicals.
     
  20. Scott Wheeler

    Scott Wheeler Forum Resident

    Location:
    ---------------
    I did something close to that. No regrets whatsoever!
     
  21. nwdavis1

    nwdavis1 Forum Resident

    Location:
    Detroit
    Square rooms are bad because they will have multiple standing wave modes at the same frequency. The same is true of rooms with dimensions that are multiples of each other.
    You would definitely not want a room that is 10 x 10 x 10 but 10 x 20 x 10 isn't much better. You really want dimensions like 20 x 14 x 8 or 24 x 15 x 10, etc.... Where neither length is an even multiple of the other.
     
  22. Scott Wheeler

    Scott Wheeler Forum Resident

    Location:
    ---------------
    even then you have issues. 20x14x8 share a multiple of 2. 24x10x15 has 24x10 sharing a multiple of 2 and 10x15 a multiple of 3. And we shouldn't stop at even foot dimensions. Idealy this should go all the way down to inches with no shared multiples in either of the three directions. It's actually not that hard to do if one is also installing full wall base traps. Kill two birds with one stone
     
  23. toddrhodes

    toddrhodes Forum Resident

    Location:
    South Bend, IN
    So something occurred to me and thought I'd raise the question here - when we say our rooms are 10 x 20, how often are they *exactly* 10.00' x 20.00'? In other words, I say my room is 9' x 12.5' but it's actually something like 9.3' x 12 5/8. How "close" do the measurements need to be to some whole number that would have a multiple of the whole number of another dimension in order to create issues with standing waves, comb filtering, and so forth?
     
  24. chervokas

    chervokas Senior Member

    The specific frequencies of modes, nodes and standing waves will be different, but very marginally between a 9 X 12 room and a 9.2 X 12.5 room. Like, the first axial standing wave along the length of a 9X12 room will be at 47Hz, of a 9.5X12.5 room it'll be at 45Hz. If you were tuning narrowband Helmholtz resonators or something to deal with a specific frequency, that might be an issue (even then, you'd really need to shoot the room with a mic, a sweep tone, and some software to really narrow in on exactly what the frequencies are where there are issues since between furnishings and the various materials actually used in the room and little differences in due maybe to mouldings or and kind of small structural cut outs or departures from exact measures, thinks will be marginally different). But in practice there's not much of a difference.

    Every room, regardless of it's size and dimensions, is going to have peaks and nulls as a result of room modes along all the dimensions -- side to side, front to back, up to down, corner to corner, and across multiple boundaries -- at multiples of wavelength frequencies based on the dimensions of the room. The only differences between a small room and a larger one are a) the specific frequencies at issue; and b) reflection times, in a small room the reflected sound is on top of you and bouncing back and forth between surfaces almost as fast as the direct sound is reaching you. But a couple of inches here and there in measurements is just going to amount to very small differences of the frequencies of the room modes.
     
  25. toddrhodes

    toddrhodes Forum Resident

    Location:
    South Bend, IN
    Dude, you are a wealth of info. Thank you for the explanation :)
     
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