Suggestions for treatment of very unusual room

C

Capt Dunsel

New member
After reading all the posts I could find about unusual shaped rooms, I haven't seen one where the walls are as convoluted as mine are. I am attaching a diagram of the room and the ceiling heights.

room.jpg


My question is: in a situation like this, what would be a good way to balance out just the monitoring area with some acoustic treatment? I've just started mixing and it seems that they tend to come out slightly bass heavy when played back on other equipment.

For example, what kind of results could I expect if I put a bass trap above the desk, and put a few Mini-Traps on stands behind the listening position, say, in a "U" shape configuration?

I'm not a professional by any stretch of the imagination, but I would like to get better frequency balance in the listening area.

Any thoughts you may have on this would be greatly appreciated.
 
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Thanks for the link. That's quite a comprehensive site, but a little too intense for my needs. I'm just an amateur trying to do small demo projects for some of the bands I play with, and other friends.

I downloaded a test tone generator, and found I have a serious standing wave at 100 Hz right in my listening position (I'm talking total cancellation!) I'm not really concerned with the rest of the room, as I'm the only one mixing.

Anyone else want to take a stab at it?

Thanks again!
 
Is one or more of your room dimensions either 11.3 feet or 22.6 feet?

(Sorry if that's too intense for ya :=) Steve
 
knightfly said:
Is one or more of your room dimensions either 11.3 feet or 22.6 feet?

(Sorry if that's too intense for ya :=) Steve
Click to expand...


OWWWW....MY BRAIN!!!!! :D


Interesting you mention that. I read your post and measured, but length and width are nowhere near either. Then I started thinking (that's when the pain began - I am a drummer after all!!) maybe it's the ceiling. It slopes from 8' at the front wall to 15' at the rear wall, and sure enough, right where my listening position is, the ceiling is EXACTLY 11 ft. 3 inches!

You're good!

So, should I consider putting some kind of trap right around that area, or would treating the corners be enough?

Thanks for the input!

P. S. By the way, did you look at the layout of the room? It's gotta be one of the stranger configurations you're likely to see in a home studio environment.
 
I did look at the dimensions you gave, and also got a headache :=(

As much as I'd like to accept your praise, I don't think a sloped ceiling will be responsible for this particular problem - it's more likely a combination of modal responses from the odd-shaped space that all manage to null out at your listening position at that particular frequency. Speaker distance from walls, and possibly that angled wall (synthesizer area) in combination with the square corner by the stairs, are more likely suspects. One phenomenon of sound is that when "fired" into a 90 degree corner, it will reflect back out of that corner parallel to itself REGARDLESS of the angle it arrives - across from the square corner you have a wall that's roughly perpendicular to the bisection of that corner angle, and that's another possible source of resonance.

The simplest thing you can try is to just move your setup (including your head) about 8" to a foot back from the wall you face when mixing, and see what happens to your null.

If you want to provide the REST of your room dimensions, I might be able to find other possible culprits for you - but by far the lowest tech way is to start moving your head forward and back, then try the same with both speakers, and see if the null goes away. Sometimes moving things as little as a few inches will change results at lower frequencies - at the higher range of human hearing, 1/4" or less can change response noticeably.

Hope that helped... Steve
 
Steve,

Here's the floorplan with wall lengths:

room2.JPG


To add to this, the ceiling slopes in two directions - the dividing beam runs parallel to the wall with the opening to the hallway.

At the risk of embarrasing myself, here are some pictures of the space:

roompic1.JPG

roompic2.jpg

roompic3.jpg

roompic4.JPG

hall.JPG


As you have probably calculated, mids and highs sound really nice in this room.

Steve, I do appreciate all the input you've given me so far. Please don't spend a whole lot of time trying to solve this (unless you like challanges! :D ). I'm sure your time is very valuable. Just a gut feeling is fine, and I'm willing to experiment and do more research on my own.

Thank you thank you thank you!

The Dunce

EDIT: The hallway is 13' long x 4' wide x 8' high (flat ceiling), with a "90 deg. "V" on the far end (45 & 45 deg. walls). Three doors lead to the bathroom and two bedrooms. Could I make a big bass trap out of the hallway?
 
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An update....

I bought a box of acoustic ceiling tiles ($20) and placed them (doubled up) on the open railing next to my listening area. The distance from the wall opposite the railing is 3' - 7" which corresponds to 1/4 wavelength of 78 Hz. It seemed to help a little with my 100 Hz problem, but not 100%. When my foam bass traps arrive, I'll experiment more.

Steve, any other thoughts on the space?

Anyone else want to chime in with their thoughts? Please feel free to offer anything that comes to mind.

Mahalo!

The Dunce
 
Haven't had time to check out your previous post/pix yet, but hope to either tonite or tomorrow - guess I'm the only one masochistic enough to try this particular "dragon"... Steve
 
Check the included chart of your main axial room modes - there are three axial modes (using the ceiling height at your mix desk) that all coincide within a couple hZ of 100 hZ - your desk looks like it could be situated at or near the 4th harmonic null related to room length (17' 3" from the left end of the room, as shown in the drawing) - your head, if it's 4'3" from the floor, could also be at a 200 hZ null relative to the ceiling dimension - this could emphasize the loss at 100 hZ; then, for the short wall behind you (with the bookshelf) you'll have nulls at 103 hZ that cancel at 2'9", 8'3" and 13'9" from either front or rear wall (as seen when you're sitting in front of the speakers, otherwise known as the "mix position")

If either a speaker or your head is at any of these null points, no amount of wattage will compensate. IF it's the speakers, moving your head will only help a little bit.

Before you get too carried away with treatment, I'd get the tape measure out and measure (1) the height of your woofers center from floor and ceiling (2) distance from both speaker centers to left, right, front and rear walls, (3) height of your ears when seated, and distance from each wall to your head

post all those measurements, and I'll save you some of the grief of figuring out what to move first... Steve
 
Sorry, here's the chart I didn't attach the first time...
 

Attachments

  • odrmmode.jpg
    odrmmode.jpg
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OK, here we go:

Left speaker -
from left wall = 151"
from right wall = 127"

Right speaker -
from left wall = 211"
from right wall = 67"

Both speakers -
from front wall - 18"
from rear wall - 186" (left speaker fires into the hallway - measurement is to the plane where the 8' rear wall is)
from center of woofer to floor = 35-1/2"
from center of woofer to ceiling = 70"

My head -
ear level from floor = 47"
ear level from ceiling at mix position = 80"
head from left wall = 181"
head from right wall = 97"
head from front wall = 61"
head from rear wall = 143"

and if it makes any difference, the monitors are Mackie HR624's, sitting on heavy neoprene vibration isolation pads (the kind used for heavy machinery).

Have at it, sir! :)
 
I'll try to finish up a graphic on this tonite if possible, it'll show you where NOT to put speakers or ears - It'll probly be tomorrow night before I get it posted. gotta run for now... Steve
 
Graphics are too big for this board, shrinking them may be a waste of time. Results - your head and both speakers need to move to the right by 9-10 inches to get out of nulls - your head is also at a minor null height-wise - your speakers need to raise to about 44 inches, and your head needs to get away from 48" where it's in another null. if you drop your head position to about 42", and possibly set your speakers on a pair of slanted MoPads to get them firing slightly downward, you should see quite a bit of improvement in sound field.

The next thing would be getting some 2-3" rockwool or rigid fiberglas up on that half-wall to your right, and also on the wall behind your desk and monitors.

If you're curious about the graphics I used, post back and I'll try to shrink them enough for this board... Steve
 
Steve,

Thank you so much for taking the time to do this. Graphics are not necessary, I'll go by your description here.

I'll make the adjustments and let you know how it turned out.

If you're ever in Honolulu, let me know and I'll have to buy you a beer (many beers in fact!).

Thank you very much!
 
"Results - your head and both speakers need to move to the right by 9-10 inches to get out of nulls - your head is also at a minor null height-wise - your speakers need to raise to about 44 inches, and your head needs to get away from 48" where it's in another null. if you drop your head position to about 42", and possibly set your speakers on a pair of slanted MoPads to get them firing slightly downward, you should see quite a bit of improvement in sound field."

Good God, man! Where'd you learn that stuff? LOL
 
"Good God, man! Where'd you learn that stuff?" -

Answer - I'm a quick learner, only took me about 22 years, and a shelf full of $30 to $150 books, on top of another 12 years in other technical fields... :=)
 
knightfly said:
"Good God, man! Where'd you learn that stuff?" -

Answer - I'm a quick learner, only took me about 22 years, and a shelf full of $30 to $150 books, on top of another 12 years in other technical fields... :=)
Click to expand...

Well it has definately paid off. I did the movements as you recommended and WOW!! Huge difference with that 100 Hz problem, and it sounds even more 'open' than ever! Can't wait for my foam to show up, so I can treat the walls like you suggested.

I'll have to make it a CASE of beer!

By the way, what's your shirt size?

Thanks!
 
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