Weird Shaped room - Need some advice...

[heartsoffire]

I have just moved into a new house and it has a third floor that makes a nicer control room thah what I had before. The ceiling at its peak is 9'10". One problem that I'm running into is sort of open and has slanted ceilings. I've attached some pictures at the web address below.

The room is a bit over 12' wide if you take out the half wall and the stairs. However, from the half wall to the right side is about 9'. It's also 16-1/2" long.

I just purchased 2'x4'x4" mineral fiber insulation and want to mount them on the front and back walls. The plan is to build a frame wit 1x8 white pine (stained). The front will have the mineral fiber insulation covered with fabric, about 3-4" of air and then 1/4" plywood at the back sealed with caulking. However, I've recently heard that it would be best to leave the back open not seal it.

I can put 4 in front and 4 in back. I was thinking about taking the diffusers, that are packed with R-13 insulation and 1/8 MDF on the back, somewhere in the room. I thought about where the ceiling angled above mix position and at the back of the room. I was also thinking about taking the Auralex Star Burst (backed with plastic lattice for hanging purposes) and hanging it above the mix position.

A couple questions:

1) Am on the right track with the 4" mineral fiber insulation and the framing? Or should I just wrap them and mount without the framing?
2) what about the T'Fusors. What would be an effect use of them. I've also thought about putting the 4" BEHIND the diffusers. However, that would take about 16" of floor space at the back of the room instead of 8".
3) What about the SunBursts?

The floor is short pile carpet.

I plan on using the LENRDS in the tracking room downstairs.

I also own about 40 pieces of the 2x4x2" StudioFoam Wedges that are currently in storage if this will add a benefit.

I'm looking to even out the frequencies for a better stereo image and better mix translation.

Lastly, should I consider putting about 2" behind the 2" Auralex on the side walls? I've done this before and it seemed to work fine. I got lazy but realize that this might not be all that wise.

I have pictures, scale diagrams, and proposed plans at the following site:

http://heartsoffireproductions.com/stud ... allery.htm

Thanks for your assistance,

Mark

[knightfly]

Mark, your post sounded familiar, so I found the identical posting on Studiotips and followed along - I would approach your room quite a bit differently than any of the suggestions there (except for needing quite a bit of absorption) - the first thing I'd do is to rotate the desk 90 degrees clockwise, and center it on the long wall. Usually this is not the best thing for smaller rooms, but as you're painfully aware this isn't "usually" -

With your ceiling profile, the only way you will get a balanced sound field for good stereo imaging is to get a symmetrical ceiling; and the only way I can see to do that is put your desk on the CENTER sloped ceiling/wall, facing AWAY from the half-wall by the stairs. - if possible, place your head at between 38% and 39% of the total distance between the front (half sloped) wall's straight part, and the wall beyond the stairwell - your speakers should be placed so that the centers of their woofers are either 1 foot or 21" away from the wall, and NOT within 6" of centered vertically between floor and ceiling. If you place your woofers at 18" from the wall, you will have them in a 4th harmonic null of your 12 foot 8" dimension; at 2 feet, they will be in the third harmonic of that dimension. In between, they will be fairly even on response.

Regardless, you will need as thick absorption behind the speakers as you can do - a minimum of 4" should work.

The sloped ceiling in front of your (new) mix position may need to be partly absorbed, but most of it should redirect early reflections to your rear without them hitting your ears - there should be more absorption on the half-wall, and on the portion of the full wall on the other side of the stairs that isn't covered (from the viewpoint of the speakers) by the half wall.

I would agree with paul that you should do heavy absorption in the flat part of the ceiling - also, both slanted walls (on either side of the new mix position) should be absorbed as well. I would lose the carpet, since you'll have higher and more even absorption on the ceiling.

The side walls (12'8" dimensions) should have absorption wherever a mirror would show you either speaker from your mix position. Once all the above is done, you'll be able to test to see if more absorption is needed. Corner traps would be the first thing, before anything other than behind the speakers and at first reflection points. These include the ceiling, but since part of your "ceiling" is sloped and the rest would be heavy absorbed, that becomes a moot point.

If the stairwell will NOT be enclosed, more absorption in its wall areas will be necessary as well... Steve

[Jon Best]

I'd agree completely with steve- you're sitting pretty well symmetrical if you make that stairwell wall the back wall. I don't think, with that ceiling, that I would consider doing it any other way.

Here's my first impression, though, and it may seem kind of weird...

I would consider a giant bass-trapping rear wall with the above configuration. I would cut 2" 703 board to shapes that fit the area, and hang it above the short stairwell wall, from the top of the wall all the way up to the ceiling. I would think it'd be ok if there was a little space between them. I'd continue that false wall all the way to what would then be the right wall, leaving a door-shaped opening where that door at the top of the stairs is. Then I'd deaden the far back wall (the right wall as you're coming up the stairs) as well, and hang the scraps in the stairwell high enough that you don't bump your head (you could even box in the little area at the top of the stairs as a vocal booth or something, but I'll leave that mental exercise to you).

Then I might hang a couple/few T-fusors in front of the absorption,if you feel you need a little life back from the rear of the room.

Then I'd just do the mirror trick on the exposed bits of the front and side walls- sit in your chair, and have a friend run a mirror along the walls. Put some absorption anywhere you can see either of your speakers in the mirror. Try to avoid hanging that 2" Auralex flat on the wall- it's just knocking off the top end without touching the midrange. If you prefer foam to 703, hang it a few inches off the wall, or tack the corners and let it bow out from the wall. Get some space behind it somehow. You may want to consider some flat pieces of thin plywood hanging at angles near the ceiling, to throw reflections back into the bass trap instead of deadening them, as you still want some bounce in a room. They'll do some low end absorption up there as well, although not as efficiently as a panel trap. I had some angled face panel traps for a sawtooth thing in my old control room, and that worked out wonderfully.

There would never be anything wrong with panel traps almost anywhere in there, although I wouldn't put them on the stairwell wall, as it's not really a room boundary. Put up as many as you can make.

At this point, I'd start listening to stuff and seeing how it sounded throughout the room. If you're sitting at the mix position, and records you know sound good, with balanced low end, and it's easy to localize intstruments in the stereo field, you're on your way. Now try walking around the room, sitting on the couch, etc., to see how it changes. If the low end is wildly lumpy depending on where you are, put in more panel traps. If the soundstage is really smeary where you know people are going to sit, try the mirror trick again from there.

Have conversations with people in there, too, especially as you add more absorption- you need to make sure the space feels natural, and not like a tomb. Pick colors with the same thing in mind.

That's my first impression, at least.

[heartsoffire]

Mark, your post sounded familiar, so I found the identical posting on Studiotips and followed along - I would approach your room quite a bit differently than any of the suggestions there (except for needing quite a bit of absorption) - the first thing I'd do is to rotate the desk 90 degrees clockwise, and center it on the long wall. Usually this is not the best thing for smaller rooms, but as you're painfully aware this isn't "usually" -

I had considered this at one time, but talked myself out of it.

With your ceiling profile, the only way you will get a balanced sound field for good stereo imaging is to get a symmetrical ceiling; and the only way I can see to do that is put your desk on the CENTER sloped ceiling/wall, facing AWAY from the half-wall by the stairs. - if possible, place your head at between 38% and 39% of the total distance between the front (half sloped) wall's straight part, and the wall beyond the stairwell - your speakers should be placed so that the centers of their woofers are either 1 foot or 21" away from the wall, and NOT within 6" of centered vertically between floor and ceiling. If you place your woofers at 18" from the wall, you will have them in a 4th harmonic null of your 12 foot 8" dimension; at 2 feet, they will be in the third harmonic of that dimension. In between, they will be fairly even on response.

I'm not following what you mean by "6" centerered vertically between floor and ceiling."

Regardless, you will need as thick absorption behind the speakers as you can do - a minimum of 4" should work.

So the plan of putting 4" rockwool with 4" of air will work OK behind the speakers?

The sloped ceiling in front of your (new) mix position may need to be partly absorbed, but most of it should redirect early reflections to your rear without them hitting your ears - there should be more absorption on the half-wall, and on the portion of the full wall on the other side of the stairs that isn't covered (from the viewpoint of the speakers) by the half wall.

Do you think putting a couple T'Fusors above the mix position on the slanted part of the wall would work?

I would agree with paul that you should do heavy absorption in the flat part of the ceiling - also, both slanted walls (on either side of the new mix position) should be absorbed as well. I would lose the carpet, since you'll have higher and more even absorption on the ceiling.

Seems to be the general concensus.

The side walls (12'8" dimensions) should have absorption wherever a mirror would show you either speaker from your mix position. Once all the above is done, you'll be able to test to see if more absorption is needed. Corner traps would be the first thing, before anything other than behind the speakers and at first reflection points. These include the ceiling, but since part of your "ceiling" is sloped and the rest would be heavy absorbed, that becomes a moot point.

Makes sense.

If the stairwell will NOT be enclosed, more absorption in its wall areas will be necessary as well... Steve

Thanks for the advice!

Mark

[z60611]

The greatest example of speaker positioning room effects I've seen in the past few weeks is:

Before subwoofer/listener positioning:
http://www.avsforum.com/avs-vb/attachme ... id=4833907

After subwoofer/listener positioning (RPG Room Optimizer recommendation in this case):
http://www.avsforum.com/avs-vb/attachme ... ntid=31016

In this case he was trying to flatten out his subwoofer from 20hz to 80hz, thereafter (above 80hz) is crossover-ed out.

[z60611]

heartsoffire:

Do you think putting a couple T'Fusors above the mix position on the slanted part of the wall would work?

I'd hold the t-fusers for last for final tweaking of room sound based on what you hear and like. In otherwords, take them out of the room for now, but be ready to be able to put them over something thickly absorbtive to reflect/deflect on purpose.

Mark Edmonds did that in his thread with great success.
http://forum.studiotips.com/viewtopic.p ... c&start=91

[knightfly]

I agree on the T-fusors - and I would NOT put them that close to you, you'll end up with specular reflections instead of diffusion.

What I meant about the speakers and the 6" thing - you do NOT want the centers of your woofers to be equidistant between floor and ceiling, but offset by about 6", either higher or lower than centered.

On the 4" rockwool + 4" air - that will be a good thing, just keep in mind that distance from the actual woofer cone to the wall can be very critical here, because the deep nulls at 3rd and 4th harmonics are pretty close together; moving the speakers forward or back by as little as an inch can make a huge difference at that point, check out the null points for your 12'8" (length) dimension on this simplified axial mode graph to see how close they are to each other - you need to be either between them (exactly) or away from them. Thickness of absorbent + air gap + majority of the speaker box might make it so you couldn't use the space that's closer to the wall than the yellow null point.

Here's the calculator I'm using for the pic that's shown -

http://www.harman.com/wp/index.jsp?articleId=131

I also like Jon's idea of making the entire stairwell into a deep bass trap, if that's doable for you - that should do everything I had intended PLUS give you more smoothing in the bass region... Steve

[Jon Best]

check out the null points for your 12'8" (length) dimension on this simplified axial mode graph to see how close they are to each other - you need to be either between them (exactly) or away from them. Thickness of absorbent + air gap + majority of the speaker box might make it so you couldn't use the space that's closer to the wall than the yellow null point.

Steve

My question is whether this really ends up applying in this shape room- isn't the above dimension really only applicable from like mid-thigh down?

[Jon Best]

check out the null points for your 12'8" (length) dimension on this simplified axial mode graph to see how close they are to each other - you need to be either between them (exactly) or away from them. Thickness of absorbent + air gap + majority of the speaker box might make it so you couldn't use the space that's closer to the wall than the yellow null point.

Steve

My question is whether this really ends up applying in this shape room- isn't the above dimension really only applicable from like mid-thigh down?

Nevermind. Looked at the pics again...

With that in mind, I'd panel trap the front and side walls,maybe 8' traps lengthwise, stacked two high, then the rockwool in front of that on the front wall. I'd imagine that and the big bass trap in the back would go just about as far as possible in minimizing modal issues.

[Jon Best]

check out the null points for your 12'8" (length) dimension on this simplified axial mode graph to see how close they are to each other - you need to be either between them (exactly) or away from them. Thickness of absorbent + air gap + majority of the speaker box might make it so you couldn't use the space that's closer to the wall than the yellow null point.

Steve

My question is whether this really ends up applying in this shape room- isn't the above dimension really only applicable from like mid-thigh down?

Nevermind. Looked at the pics again...

With that in mind, I'd panel trap the front and side walls,maybe 8' traps lengthwise, stacked two high, then the rockwool in front of that on the front wall. I'd imagine that and the big bass trap in the back would go just about as far as possible in minimizing modal issues.

[z60611]

Jon Best:
There's some more drawings of the room in this thread: Weird Shaped room - Need some advice... by heartsoffire at StudioTips forum