[brj]

How important is it to treat a sloped ceiling, and how would one go about it if needed?  (For example, is it better to treat the flat surface itself, or the edges where the slope joins the wall or ceiling?)

If speaker placement is flexible, how much should the sloped ceiling factor into speaker positioning?


My system is currently located in my living room, which I'm increasingly finding to be acoustically unfriendly.  I have 8th Nerve Adapt Rectangles along all of the ceiling/wall edges, and plan to build some free standing cylindrical bass traps (disguised as plant stands) to place against the rear and possibly front walls.  Because the living room opens up to other rooms in all directions and has windows or furniture along the remaining 3 significant walls, I can't really treat 1st reflection points or the front and rear surfaces.  The only possibly treatable surface that remains is a sloped ceiling.  Ignoring the remaining level 12' ceiling (spotted with lights, vents and a ceiling fan) and the rear wall that will eventually have bookcases along its length, this sloped ceiling is the single largest surface in what is still a relatively "live" room (although somewhat less so after the installation of the Adapt rectangles).

The sloped ceiling rises from an 8 ft' height at the front wall up to a 12' height over 6' of the room's 18' depth, and currently has the speakers located under it, almost acting like an amphitheater.  For reference, the speaker baffles are about 3.5' from the front wall and thus just past half of the depth of the sloped ceiling.  The listening position is about 5.5' from the back wall.

If the speakers stay where they are, I'm willing to consider treating the sloped surface in some manner if it would make a significant difference.  I can possibly rotate the room to place the speakers firing down the length of the sloped ceiling, although in this case, any treatments on the ceiling would probably make the room feel visually unbalanced.  (I've also avoided this setup because it just changes, rather than improves, the asymmetry of my room layout while forcing the speakers closer together at the same time it forces the listening position to be further away.)

Any thoughts on treating a sloped ceiling in general, or the specific situation I described?

Many thanks!

[Frihed91]

See sloped ceiling in picture.  Treatment for awful rooms: near field listening.  The speakers are 4 feet and 6 feet from the side walls and 3 feet and 20 feet from the end walls.  I listen about 6 feet away. The speakers are 6 feet apart.

[bpape]

If this is for 2 channel listening, I generally treat sloped ceilings like that with a series of framed 6" wide x 4' long x 3.5" thick absorbers.  Space them out so that the distance between them (edge to edge) is about 1/3 more than the inside of the frame - so about 8".  This provides good spread absorbtion without overdeadening things.  The wood frames also act like a crude well diffusor.

I find this to be a good solution in that situation that leaves things a bit more lively and diffuse while still giving some decay control throughout the space.

Bryan

[brj]

Thanks for the replies, guys!

To clarify, yes, my main focus is 2 channel listening, but if the system stays in my living room, I'll probably eventually integrate the system into a 5.1 setup for movies.  All compromises, however, will favor 2 channel  listening over movie playback.

Unfortunately, nearfield listening isn't really an option due to necessary traffic patterns.  I'm basically compromised by the fact that this is a living room first and a listening room second.

Basically I expect that I'll be able to fix some room issues with digital room correction, but I want to do as much as I can with aesthetically harmonious "analog" room treatments first.  Bass traps stealthed as plant stands are step one, and I'm looking at possibly treated the sloped ceiling as step two.  While I can probably get FR benefits similar to treatments from digital room correction, I can not, to my knowledge, address ringing.  This is the primary reason I'm thinking about treating the sloped ceiling, although the ringing might reduce slightly once the bass traps and remaining furniture is installed.

bpape, any comments about system orientation with respect to the sloped ceiling?  I'm hesitant to treat the sloped ceiling and then rotate the system so it fires down that axis.  This would add further, although possibly beneficial, asymmetry to an already significantly asymmetrical room.

[Scott F.]

A number of years ago I had one of my clients ask me if I knew how to control the sound in their multi-purpose room (it was in an elementary school). When I went to inspect the room, it was extremely cool, something many studio's would die to have at their disposal. Heres a pic of the 'before'.




The first thing I did was walk dead center of the room and clap. It seemed like the sound went on forever. The natual reverberation of that room would have been awesome for recording. Trouble was, school assemblies and lunch were served in this room. Imagine 100, first through fourth graders all yapping away at the same time, each of them trying to talk over the top of the noise that would build up in this room.

I did some measurements with my Sencore SP295 and found that the rooms RT60 time was well over 2 seconds. Not too suprizing when you take a hard look at the room. The ceiling is essentially an octagonal  bowl made of tongue and groove pine. The owner wanted to preserve the look of the wooden ceiling yet quiet the room down at the same time. I took the idea of what Golterman Sabo markets as 'Clouds' which are usually randomly sized and placed and made the room more semetrical (I was dealing with an ex-math/science teaher turned superintendent). Heres a couple of pics of how it turned out.



As you can see, I made panels that were suspended from the ceiling. They hung about 3 or four feet below the ceiling. They are suspended from 30 pound test, fishing line. Golterman sells these little auger-type thingies that screw into the back of the OC703. They have an eyelet on the back of them for suspension.



This is a pic that shows the air space behind the panel to the ceiling. It gives you a little better idea of what I did.

When I was done with the room, it was dead quiet. My RT60 went from well over 2 seconds to nearly 1/2 second. The air gap behind the panel allowed the sound (essentially) be absorbed twice (of sorts). Brian or Ethan feel free to jump in and correct my inability to remember the exact term or type of treatments I installed, its been a while since I cracked the cover on my acoustics handbook as I play an ME/EE by day.

It may not be pretty but it damn sure worked. Not sure if you can talk others you live with into something similar, but you might consider it. If you wanted to do random shaped clouds that were suspended from the vaulted ceiling, I'd bet Bryan would whip some out for you.

If you go with clouds, I've got something cool you could incorporate to it. Take and mount strip lights on the back side that shine up into the ceiling to give you some idirect light for the room. Put them on a dimmer so you can control the ambience. Might be kinda cool.

[bpape]

I personally wouldn't rotate it exactly for the assymetry reasons you described. 

I misunderstood the original post when I first responded - I apologize.  For the way it is I'd consider straddling the wall/slope corner with some 4" thick absorbers and then use some of the same 6" x whatever lengths but turned horizontally and staggered.  I'm trying to create some diffusion more in the vertical plane and as the sound comes down the slope.

Bryan

[brj]

Scott, that is one heck of an elementary school!!

In that room, the cloud treatments seem to integrate reasonably well, although hiding even part of that wonderful timber roof is somewhat unfortunate.  How think are the panels used on that ceiling?

The concept of cloud treatments seems pretty slick in general, but I'd have to mock something up to see how visually intrusive it would appear in my much smaller living room.  I like the idea of the hidden strip lights, too.  You could go with multi-colored LED lights if you wanted to get really flexible... or crazy!

It looks like you can buy the real thing here, but this seems like a semi-reasonable DIY project as well.  This gives you the option of custom colors and even artistic finishes.  Just for reference, what kind of price ball park are we talking about for 2 or 3 average sized Golterman & Sabo clouds?


Bryan, thanks for the clarification!  Note that at the moment, the speakers are currently below the sloped ceiling firing out from the 8' front wall (of floor to ceilling windows with 2" blinds) toward the 12' back wall (which will eventually have bookcases).  I would expect that sound reflected from the back wall would hit the sloped ceiling and head down to the floor (although not quite perpendicularly, as the slope is a bit less than 45 degrees).  The floor is a concrete slab with contractor grade (e.g. thin) carpet.  I confess that I was originally pondering something along the lines you describe, but of a 2" thickness with camfered edges and various sizes.

[Scott F.]

Those panels were 2" thick OC703. I actually bought those from Golterman Sabo. The average panel size was about 6' long by 4' wide. The last panels were 12' long so they were a special order. For the 32 panels it ran me $6400 or about $200 each. I used the Guilford of Maine materials which are one of the more expensive materials. Depending on the size of the panels and the type of material you choose, I would think that price would come down a bit.

It should be easy enough to do the DIY thing. All you need to do to make a longer or wider panel (the standard size of OC703 is 2'x4') is to take several coat hangers, straighten them out and stick one half way into one panel and halfway into the other. It sort of works like a dowel rod. Use multiple for each butt joint. You'll also have to use adhiesive on the butt joint. Liquid Nails should work just fine.

Just take some cardboard and use it as your mock ups. Some simple string and tape or a thumb tack should work to suspend your mock ups. The material you choose can be fastened with spray adheisive applied to the 703. You could probably call Golterman and order those auger thingies (the RE2's). Just make sure that you order the unfaced 703 as you want absorption from both sides. If you can only get faced (FSK), just peal the facing off. Cutting the fiberglass is really easy. A good sharp steak knife is all you need. Then just whittle away at the square panels until you find a pleasing, rounded cloud shape you like.

Not sure if you have bass issues too. If so, order rigid mineral wool rather than fiberglass. It will do a better job on frequencies below 100Hz.

[bpape]

Understand the layout and you're right about the bounce coming back at the angle and then down.  That's one of the reasons that the front wall should also likely be treated with some combination of diffusion and absorbtion.  Doing a 1'x1' cube running all accross the front wall/floor intersection will help with some of the reflections and also give you a bit of bass control without being obtrusive.

Bryan

[accentstryping]

 As ya'll seem to be up on acoustics, we are having a gala type event and is alot like the on pictured in the school, with a lower ceiling height 14-20',and about 2/3 the sq. ft.
  Since this is a rental room in a hotel, and is only temporary, what if any effect would just filling up about 200 helium ballons do to dampen the echoes? If we just let them float up into the ceiling?

                                                                                                   Just A Thought...

                                                                                                             Michael

[Scott F.]

The ballons should help diffuse the sound pretty well. It won't help absorb, but it should help calm the room down some if you get enough coverage.