[bassboy]

My old room was 11x14.  It had strong modes down to 40 and strong room gain.  My new room is basically 19x27.  Speaker setup is far from ideal (along the long wall) but for the time being I can't change that.  This room seems to suck out the bass, there is basically nothing below 60 hz, and not very strong above that either.  I was able to try the speakers set up along the long wall temporarily, and it helps alot, but still not much bass.  I have to decide very soon whether I will build a wall to divide the room into 2 rooms.  Below is a picture of the room that I drew in PAINT.  It is not to scale, and I only added the important dimensions.  The red line is the proposed new wall.  This would make my listening room a 19x16 rectangle.  I CANNOT make that wall anywhere else, it can't be moved an inch to either side because of the location of the windows in the room.  The green rectangles are where the roof slopes down towards the edges of the room.  The height of the ceiling in the flat high part is 10.5 feet, and in the area covered by green rectangle, it slopes down from 10.5 to 7.5 feet.



So I need to decide if I want one big room or 2 small ones.  Neither have great proportional dimensions, but the smaller room has a couple of advantages.  I only have enough carpet for the 19x16 room.  The extra storage room would allow me to move some large appliances out of the room to lower the noise floor.  Additionally, in the smaller proposed room, I could set up my speakers along the 16 foot wall, and then the sloped sections of ceiling would be front and back instead of side to side.  This seems like it might be an advantage to my dipole speakers, almost like treatment by eliminating the corners.

Please help me decide.

[bassboy]

I realize that answers take time in these online forums, but I have a very limited number of days before this decision is made for me due to a need to have this room completed before the snow falls.  (At present, the room is uncompleted, uninsulated, etc)  ANY OPINIONS ARE VERY WELCOME.

I just want the best starting point to build a dedicated listening room.  I have plans for extensive room treatments, but I need to know which choice of room dimensions are likely to be easier to work with to provide a balanced frequency response and pleasant accoustic properties.  Please advise.

[Ethan Winer]

My new room is basically 19x27.  Speaker setup is far from ideal (along the long wall) but for the time being I can't change that.  This room seems to suck out the bass, there is basically nothing below 60 hz, and not very strong above that either.

That's likely because you're too close to the wall behind you.

I was able to try the speakers set up along the long wall temporarily, and it helps alot, but still not much bass.

I'm sure you need bass traps. All rooms need bass traps!

I have to decide very soon whether I will build a wall to divide the room into 2 rooms.

You could go either way. A larger room is better, but it needs more acoustic treatment overall because there's more total reflecting surface. So now it's down to money. The cost of building a wall and treating a somewhat smaller space, versus leaving the room large which requires more total treatment. How much money you got?

I only have enough carpet for the 19x16 room.  The extra storage room would allow me to move some large appliances out of the room to lower the noise floor.  Additionally, in the smaller proposed room, I could set up my speakers along the 16 foot wall, and then the sloped sections of ceiling would be front and back instead of side to side.

Sold!

--Ethan

[bpape]

As much as I like the idea of a nice large room, if it's at the expense of having to have appliances and other noise generators in the room, I'd likely agree with Ethan that the 16x19' room would be the best bet. 

That's still a nice sized space.  Plan ahead in terms of speaker and seating location, how those will influence reflection points, bass buildup, etc. - and where you can put doors and windows to stay out of those places so they're easily treatable - but still not taking up corners (especially not front corners).

Bryan

[bassboy]

Thanks, that's exactly the information I was looking for. 

This room is a reconditioned garage, concrete floors, uninsulated drywall, windows and doors in very difficult positions, but not unworkable.

At this point, since I have an idea of what I want, I am thinking about making the new wall entirely out of bass panel traps and diffusion units, which obiously will cost more than drywall, but in the long run will be less costly than placing these treatments over a new drywall wall.  Then I can concentrate on the other walls and ceiling later, with broadband absorbtion and more diffusion.

[Bob in St. Louis]

Not that my two cents are worth much on the subject of acoustics (don't laugh Bryan... ), but I'd agree with Misters Pape and Winer respectively. 16 X 19 is still a nice sized room. And having a bit of additional insight into your situation BB, I think having that extra unfinished space would be a nice place for storage and baffle building, rack building etc...
Not having enough carpet for the entire room, the cost of finishing, insulating and furnishing the entire room, and then treating the entire room all factor in my opinion.
BB, Please understand my opinion shouldn't be taken because I'm giving advise for any reasons regarding the potential acoustic implication with either size, simply for the up-front/immediate cost factors, extra work space, and extra storage space, I'd opt for the "plan B" smaller room.
16 X 19 is plenty big (obviously we all want a "grand hall"....), The pro's can advise regarding whether that size/shape is sonically advantageous or not.

Bob

[brj]

I am thinking about making the new wall entirely out of bass panel traps and diffusion units, which obviously will cost more than drywall, but in the long run will be less costly than placing these treatments over a new drywall wall.

If you are going to have noisy mechanicals in the other room, you might want to reconsider the use of a standard wall, as it will provide isolation.  Better yet, you might want to consider a double layer of drywall with Green Glue in between.

[bassboy]

Hey Bob, thanks for that.  Storage space is always good, but I was willing to TRY to pull out all the stops for the larger sized room, if significant gains could be had that way.  Cost is not too much of an issue here, as I have a good bit of raw materials and furnishings are coming out of my old listening room.  Carpet was free, I should have plenty of 2x4's around somewhere, but as you know I am sorely lacking in the insulation dept.  BUT since I am not personally paying for the insulation job OR the new wall, my limited funds will go a long way on what is left.

Brj, the appliances in question are 2 freezers and a fridge, so while I agree that isolation is important, I'm not sure that the expense of a double layered green glue wall is warranted.  My plan consists of near total isolation through the new wall anyway.  Frame the new wall with 2x4's and 2x6's.  Seal the wall/wall/ceiling/floor junctions with silicone or liquid nails to make it airtight along the perimeter.  Insert the rigid insulation between the studs, as per bass panel construction.  Finish by covering front and back of wall with plywood instead of drywall, sealed along all 2x4/plywood joints with silicone or liquid nails to make the individual panel traps airtight and independant of each other.  Basically an airtight wall made of several bass trap panels (and diffusion at key points).  I don't think I'd hear the freezers through that.  That's about 18 sheets of plywood to make this bass trap wall and the rest of the room will still need significant treatment, but this is enough of a project for now.

[bpape]

A piece of advice - do not try to combine a wall surface to be isolation and treatment - it doesn't work.  Build the wall for isolation - then treat for the inside of the room.  They're too very different goals and different solutions.  Even just $50 worth of clips and 2 layers of drywall (even if you use liquid nails instead of GG) is well well well worth the effort.

Bryan

[Bob in St. Louis]

Better yet, you might want to consider a double layer of drywall with Green Glue in between.

BB, I'm liking this idea as well.

Also BB, Bryan and I spoke last Saturday night EXTENSIVELY (....and thank you again Bryan) about this very subject. My mistake was building the room "normal", and then dealing with the mess I've created after it's too late. Building the room "right" in the first place with Green Glue, and isolation in mind will yield better results in the end. It'll also be cheaper in the long run because you won't have to "fix" anything.
The constrained layers have multiple benefits of keeping the refrigeration equipments noise away from you.....Your noise away from the house, and may.....just may....provide some additional isolation from those Canadian winters.
My recommendation is to use all your cash on making that smaller room the best it can be without spreading things (isolation, insulation, treatments, wall 'finishings'{drywall/paint}, furniture etc...) too thin.

Also, since you have the proverbial "blank canvas" at your disposal, you might want to check into "the golden ratios" for two channel room dimensions. It may require the loss of a window or two, but hey....the ability to see the outside world is overrated anyway. 

Bob

[bassboy]

Ok brj, you were right and I was wrong, which is not uncommon.  So a bass trap wall will not be effective as isolation.  A dual layer green glue wall might be the best best to start.  I won't have to pay for the first layer of drywall, but the second layer and the green glue will definitely come out of my pocket, so I'll probably see how much isolation I get from a standard wall before ordering the extra materials.  Besides, what's the point of isolating one wall completely and leaving all the rest alone?  Total isolation of the entire room is going to get VERY costly.

Bpape, you saved me a bunch of time and frustration by explaining that, thanks very much.  Making (stupid) mistakes on a project of this scale is simply not an option.

Bob, does that mean you are going to start all over again?

(By the way, I never even thought about removing the existing windows and doors, but that sounds SO nice.  I don't think it would go over too well from an exterior view POV though, since I have no siding to match the rest of the house and cover up those gaping holes.)

[bassboy]

Now is probably a good time to ask about the space above the ceiling, since it will be indiscriminately filled with fluffy fibreglass in the next couple of days.  There is a lot of space up there but completey unusable for anything.  The ceiling is 1/8 or 1/4 inch OSB (the cheapest chipboard you can get).  This WILL eventually be covered with drywall, or removed and then drywalled. 

But for the time being, from a bass trapping perspective, is there anything special I can do to increase the bass trapping abilities of this otherwise useless space?  Or should I just insulate as any other ceiling and add bass traps to the ceiling inside the room?

[MaxCast]

Don't forget to run separate AC lines from those freezers.

Is there living space above the ceiling?
How much space is there?

[bpape]

You're right about the isolation.  In a perfect world, it should be done to all surfaces.  In your case, it's not an option.  It's now more about keeping sound out of the room.  That just takes a little planning, a well insulated, caulked tight wall - and a lot of mass (double drywall).  The Green Glue is nice and for one wall is not a large expense in the grand scheme. 

If it comes down to doing it or not, even adding another layer with just liquid nails (trowelled on ) will provide the mass without the viscoelastic damping.  It just acts like a REALLY thick piece of drywall.  This still provides the benefit of lowering the resonant frequency of the wall and also allows it to absorb (a little) at a different frequency than the other walls broadening the inherent absorbtion in the structure itself.

Bryan

[bassboy]

Ok, I'm sold on the dual layer.  Drywall is cheap.  Green glue isn't, so I'll have to compare the price with liquid nails and estimate how much I will need, I assume all that info is on their website, so I better check it out.

MaxCast, there is no living space above, just a peaked roof hidden by the cheap chipboard.  It's a large space, soon to be filled (lined between the studs) with fluffy insulation, unless there is a better solution that addresses accoustic treatment and a temperature barrier.

[bpape]

Retail on Green Glue is $177 per case (discounts are available  ).  A case is 12 tubes that will do 192 sq ft (6 sheets) at the recommended 2 tubes per sheet.  So a case is enough to do a 24' long wall that's 8' high.

Overall, I think you'll find that GG is about double the cost of liquid nails so maybe an extra $80 for 12 tubes.

Bryan

[Bob in St. Louis]

Bob, does that mean you are going to start all over again?

In a heartbeat.
But I have this female companion that has objected to building a new house, or building a detached structure from our existing house. I have a lot of grand ideas (some of which were de-bunked by Bryan last Saturday.. ) But it's going to require an entirely different room. You can imagine the wife's reaction when I told her that we should sell the house we built 6 years ago so I can have a bigger (....better, faster, more...) room.  The first thing I'd do would be to have 12' +/- ceilings.

Regarding BB's room....Bryan, if I understood you correctly Saturday....You said that even three layers of 3/8" drywall with Green Glue (or Liquid Nail) would be better than two layers of 1/2"? If you could explain the advantage of multiple (meaning more than two) layers, that might help BB.

Max, good idea about separate AC circuits for the freezers. Hell, since there's three freezers, I'd put them all on a different LEG of the breaker box. You'd have near constant brownouts with three refrigeration units constantly clicking on and off. 

Besides, what's the point of isolating one wall completely and leaving all the rest alone

IMHO, if you can only 'shoot your wad' on one wall, I'd definitely do the 'new' wall. Not the outside walls. The hum from the freezers will raise your noise floor to .....???? !!!!! Db's

Bob

[bpape]

What I was saying is that all else the same, 3 layers of 3/8 is more mass than 2 layers of 1/2" - plus I get 2 layers of damping material.  It's expensive and time consuming and I wouldn't do it in this case.  But, if you want it really quiet and have the money and time, it's a nice way to go.  3 layers of 1/2" would be even better.

Bryan

[bassboy]

Well, Bob, 3 layers might just be pushing it a bit.  You know that look people get on their face when they see you doing something they don't understand?  Oh yeah, sounds like you do.  (By the way, the truth about women is that if they get theirs first, they might let you get yours someday, hopefully before the 3rd Tuesday of never.  For example, turn that room of yours into a personal spa for her and see how soon you get your new room.  She might even be happy with using it as a massive walk in closet.)

Thanks for the green glue info, Bryan, I still have to check out the website to see how to properly apply the stuff.

[bpape]

Instructions are easy.  Put up the first layer with screws and put on a firecoat of tape and mud.  'Randomly drizzle' the Green Glue over the next sheet.  Do not trowel it out, try to spread it or anything else - just let it find it's own level when you screw the next layer on.  Don't overlap joints.

All done.

Bryan