A proper (ideal?) room for Klipschorns, help needed!

[Istari]

In both corners where the Korner horns will be, place the 2x4's every 8" on center instead of every 16' on center. i would also use some construction adhesive (or drywall glue) on the drywall/2x4's just so they won't rattle. Of course, it would be best if you could glue and screw all of the drywall in that room.

Are you going to put in any insulation? That will help a great deal too. If the walls are empty, they could ratttle when your system is cranked.

[yrtimed]

I was going to do some basic acoustic treatment, probably. Insulation - I do not know whether I need it, as the house is in a quite area.

What kind of insulation would you recommend? At some point I was thinking of double drywall with Green Glue on walls and

ceiling. Probably, "Room in a room" would be too much, and also would eat a lot of space.

[Istari]

The "double drywall with Green Glue on walls and ceiling" is a great idea.

I wasn't thinking of the sound leaking out to the main house, just a way of helping to keep the resonance down in the space between the walls. I have used the Owens Corning Pink fiberglass batts that are paper backed on one side.

[DrWho]

I looked into "Master Handbook of Acoustics", and played a little with this and this calculators. The following seems to be close to the best I can get, given my size restriction:

I wouldn't put too much faith into magic room ratios...while it certainly provides spatial distribution, you still listen at one spot (or two in this case). The distribution of modes at the listening position is what matters most, but that's a function of both the room shape and the location of the listening position. The magic room mode calculators don't take this into account.

I haven't had the time to run the numbers on your room dimensions/listening position (and probably won't for quite some time), but I would highly recommend reading "Sound Reproduction" by Floyd E. Toole as he discusses this topic in great depth.

Another thing you should avoid is making the walls too stiff. The front corners where the khorns are located should be stiff (basically built as rigid as you would a loudspeaker enclosure), but it might make more sense to build some false walls for the khorns instead (and then you'll have more flexibility with their location in the room). The rest of the walls don't need to be stiff though and there can actually be advantage to letting bass travel through the rest of the walls in the room because it will reduce the magnitude of the room modes. However, if sound transmission is an issue, then you'll have to trap the bass in the room...

Btw, do you already own the Khorns?

The vertical polars on the Khorn are actually quite tight so the vaulted ceiling probably won't have as large of an effect as it might with some other speakers. The reason I was asking about the shape of the roof is that the open rafters might actually be a better solution (unless of course you don't like what it would look like or desire better thermal insulation or whatever).

[yrtimed]

Istari,

Thanks, I will probably go for some fiberglass insulation too. As the thing is in the garage, heat insulation is also important, so the more I have is probably the better.

Btw, do you have any "tricks" how to make heating/cooling quieter? Our heating system is forced air.

[yrtimed]

Mike,

Thanks for the help!

I just looked into the book you recommended. If I understand correctly, he basically says that the room dimensions are not everything, and it's likely that the things will have to be corrected later. I am fine with that, I am just trying to start with some "reasonable" dimensions, afterwards I'll probably add some treatment.

Btw, would you recommend adding "standard" acoustic treatment (bass traps, reflection-free zone, etc.) or first performing acoustical measurements and then addressing specific problems?

How would you actually make the walls not too stiff? Say, using double drywall everywhere is, in your opinion, not a good idea?

Yes, I already have the Khorns.

If I go for open rafters, that doesn't have to be all the way to the roof, right? Can I just build the "ceiling" above the rafters (solving the thermal insulation issue)?

If I do that, what ceiling shape (and height) would you suggest?

[Rudy81]

You are smart to concern yourself with room acoustics from the outset. FWIW, from everything I have learned on room acoustics, any room you design will have acoustic issues. Fitting your room within the golden constraints is a great start, but all rooms have modes and acoustic problems due to the nature of acoustics. From my perspective, by putting in a sloped ceiling, you are going to complicate the solutions for any problems you find by adding more angles to the problem.

If your room is going to be striclty a HT and/or listening room, I say do what you need in size and treat any problems accordingly. I recently finished treating my HT for some serious acoustic issues. All the treatments were DIY and no, they would never pass the WAF test. But, it is a listening room. I have a 9'2" celing and only treated a very small portion of the ceiling for first order reflections.

The room is about as flat in frequency response as I can get it now and it did not take much in the way of money....just some work and construction. Take a look at my signature link and you can see some pictures of my layout. My room is a little larger than you are considering, 20'W x 27' L x 9' H, and is well outside the golden measurements. I could have made a smaller room within a room, but then that would have reduced the seating area.

[yrtimed]

Rudy,

Thanks, I'll have a look!

Briefly to your comments: This is going to be a listening room in the first place (one day I might add a projector and a pull-down screen between the speakers, but probably not before I am done with all the stereo upgrades I have in mind, including the acoustic treatment). As well, I'll have my study there (I often work with quiet music playing "in the background"). That is why I am thinking of the couch as the primary seat, but the desk and the chair should also be there.

[Rudy81]

Other than making a perfectly square room, I would make the room as large as possible. Also, don't be too afraid of not having a perfect corner if it would advantageous. I don't have perfect corners due to windows, and even if I did, would not use them because I sit too far back for ideal listening due to my screen size and projector setup. I made some false corners and it worked out great since I can toe in the speakers.

The ceiling issue is totally up to you, but you should look into the acoustic issues with a sloped ceiling. I'm not very familiar with those particular issue.

I will say, that your room acoustics will be the single most influential item determining the quality of sound you will hear in that room. Time spent on this issue will pay more dividends than anything else.