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How to Deal with a Room Where Symmetry is Impossible?
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bonestar
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28th January 2013
Old 28th January 2013
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How to Deal with a Room Where Symmetry is Impossible?

Here's my layout...

[IMAGE DELETED]

The long north wall is 23' 5". The west wall is 15' 9" total but is unusable to put a desk as there are two storage rooms there and a big set of stairs between them (not shown). The long south wall is 15' 6". Right now I have a couch against that wall. My mix desk is currently against the east wall, which is 12' 9" long. I can't centre the desk, though because of that door there...



Any thoughts on whether I should move my desk? I like it where it is for several practical reasons (it's also a rehearsal space and I have a band set up in the room), but it's not symmetrical. Though I don't think I can really achieve symmetry anywhere in this room. I'd like to apply room treatments - bass traps and the like - but where? If those aren't symmetrical, I'd imagine all kinds of problems would ensue.

Any comments from anyone who knows this stuff would be much appreciated.
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28th January 2013
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28th January 2013
Old 28th January 2013
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I'd face the S wall. Then I'd make a two piece temporary floor to ceiling partition / treatment extending to the N to make that portion of the room more rectangular. The partition would leave a large opening to get into the remainder of the E end. So one partition would touch the N wall and make a logical spot for a bass trap. The other would meet near the S wall where the angled wall heads east with the door in it. I realize this complicates the recording part of the deal but you could get a little isolation by putting the vocalist or drummer in the E end.
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28th January 2013
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Quote:
Originally Posted by Syncamorea View Post
I'd face the S wall. Then I'd make a two piece temporary floor to ceiling partition / treatment extending to the N to make that portion of the room more rectangular. The partition would leave a large opening to get into the remainder of the E end. So one partition would touch the N wall and make a logical spot for a bass trap. The other would meet near the S wall where the angled wall heads east with the door in it. I realize this complicates the recording part of the deal but you could get a little isolation by putting the vocalist or drummer in the E end.
+1
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28th January 2013
Old 28th January 2013
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Quote:
Originally Posted by Glenn Kuras View Post
I would face that corner to the left of where you are now. Test with the following program.
Room EQ Wizard Tutorial - GIK Acoustics
Thanks. I'll definitely test as soon as I pick up a measurement mic. Hopefully this week.

Just to clarify - are you referring to moving the desk to the northwest corner? Or just angling it so that instead of facing east it's facing into the northeast corner?
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28th January 2013
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Yes,
Syncamorea's idea is not bad either.
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28th January 2013
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Quote:
Originally Posted by Syncamorea View Post
I'd face the S wall. Then I'd make a two piece temporary floor to ceiling partition / treatment extending to the N to make that portion of the room more rectangular. The partition would leave a large opening to get into the remainder of the E end. So one partition would touch the N wall and make a logical spot for a bass trap. The other would meet near the S wall where the angled wall heads east with the door in it. I realize this complicates the recording part of the deal but you could get a little isolation by putting the vocalist or drummer in the E end.
Interesting idea. That would almost definitely make for a better mix space. As you say, it would probably complicate the recording / rehearsing part. Then again, it would give me sort of a quasi-isolated tracking room. I'll have to think that through. Not sure how I'd construct the partitions. I imagine there's plenty of ideas and info I could find online, though.

Hmmm....
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29th January 2013
Old 29th January 2013
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Symmetry is most important from the listening position forward. I'd say your best shot at symmetry is to be close to where you are now, but just move the setup to the right a bit. Perhaps the side table to your right can be moved to the left against the side wall once you move your desk toward the center of the room?

At the end of the day you will need to try a few things to test, there are lots of good ideas in this thread. For complex, non-symmetrical rooms experimentation/testing is the best way for sure.
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29th January 2013
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Quote:
Originally Posted by bonestar View Post
Not sure how I'd construct the partitions. I imagine there's plenty of ideas and info I could find online, though.
I've made floor-to-ceiling gobo-like partitions. They are kind of a pain in the butt to get set up but once you do, it's golden. The key is to measure carefully, make it undersized then make up the difference with a stiff foam. I bought a closed cell foam at a hardware store. The gobo was made from 1" thick x 6" lumber to form a rectangular box, then one side was covered with thin plywood (luan, actually). I bought a super-thin carpet-like material and glued and stapled it over the luan and the 1x6 sides. 6" attic insulation was put in the cavity, cloth stapled over then the cloth side covered with slats of various widths. Gaps between slats was ~1/4". Once set up, I used pieces of trim along the ceiling and flor to hide the foam and tie the sections together. ~2' wide sections with 24" wide attic insulation, unfaced. You have to compensate height wise to get them to fit and the thicker you make them the more you have to compensate. So if you went with 2" OC 703 and made the gobo sides out of 1x2" lumber, you could make a tighter fit and use thinner foam. With the 1x6" box I mentioned, the total foam thickness is ~2" and I split it into a top layer and a bottom layer. To be safe, I recommend building the box, tack on the luan, then test the fit in the room before doing the actual assembly - where I recommend glue and screw.

I'm about to make some similar temporary walls using drywall on both sides of the box. They should provide a bit better isolation. I can hardly wait, seeing as how I detest drywall...
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29th January 2013
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Quote:
Originally Posted by jwl View Post
Symmetry is most important from the listening position forward. I'd say your best shot at symmetry is to be close to where you are now, but just move the setup to the right a bit. Perhaps the side table to your right can be moved to the left against the side wall once you move your desk toward the center of the room?
After walking around the room a bit last night and mentally running through a few different configurations, I think this might be my only option. Any other configuration improves the mixing area to the serious detriment of the tracking area. Unfortunately, with a multi-use room like this (mixing, tracking and rehearsal), I'm sure I'm going to have to compromise something.

Regardless, I'm going to test the room this week and see what I find. I suspect I'm going to at least need some bass trapping and will wish that door currently to the right of my desk wasn't there since it prevents me from putting traps in the corners.

If anyone else has any suggestions, I'd love to hear them. Otherwise, I'll post plots shortly.

Thanks!
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29th January 2013
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Quote:
Originally Posted by bonestar View Post
I suspect I'm going to at least need some bass trapping and will wish that door currently to the right of my desk wasn't there since it prevents me from putting traps in the corners.
Just make a floor-standing corner trap. They work great. You can use carpet on the bottom so they slide easy and some cloth or foam as contact spots for the walls or door to keep vibration noise down.
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29th January 2013
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Quote:
Originally Posted by bonestar View Post
After walking around the room a bit last night and mentally running through a few different configurations, I think this might be my only option. Any other configuration improves the mixing area to the serious detriment of the tracking area. Unfortunately, with a multi-use room like this (mixing, tracking and rehearsal), I'm sure I'm going to have to compromise something.

Regardless, I'm going to test the room this week and see what I find. I suspect I'm going to at least need some bass trapping and will wish that door currently to the right of my desk wasn't there since it prevents me from putting traps in the corners.

If anyone else has any suggestions, I'd love to hear them. Otherwise, I'll post plots shortly.

Thanks!
If you can do that then great. Just try to get as centered as possible and keep any treatment symmetric from where you sit forward.
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29th January 2013
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Quote:
Originally Posted by Glenn Kuras View Post
If you can do that then great. Just try to get as centered as possible and keep any treatment symmetric from where you sit forward.
I think it'll require a new desk. The current one will be too wide to centre it. Hopefully I can trap sufficiently along the wall/ceiling boundary above the desk rather than in the corners. A floor-standing corner trap would work in theory, but that door actually gets used a lot during sessions (storage and beer fridge are through there ). So it wouldn't be ideal. I'll measure before doing anything, though.
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29th January 2013
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Be sure to measure but also try facing into that corner. It might just work there. Crazier things have happened.
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30th January 2013
Old 30th January 2013
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RTA

The RTA feature in REW is great for fast impressions.
Jeff H has also come up with a great idea. Place the speaker at the listener position and move the mic about in the likely speaker position zone. Reciprocity.
Visual Symmetry and acoustic symmetry are often quite different. Concrete walls are hard and reflective at LF, sheetrock is not.

DD
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30th January 2013
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OK, I moved my speakers over to the position they'd be in if I centred my desk along the east wall and did some measurements with REW from where my listening position would be in that configuration. I've attached the results, including the IR.

So, how bad does it look?
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30th January 2013
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You want to measure one speaker at a time and post both tests. BTW how is the room treated now? I would also recommend getting those rugs off the wall if that is what I am seeing. You don't have much upper energy left in the room from what I can tell.
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30th January 2013
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A/B

Pretty bad I suppose, but compared to what?
You will need a measurement in each of the possible locations.
Then you will be comparing rather than asking to evaluate.
Again, the RTA gives instant visual feedback while you wander about with the mic, and Jeff's reciprocal idea.
DD
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30th January 2013
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Quote:
Originally Posted by Glenn Kuras View Post
You want to measure one speaker at a time and post both tests. BTW how is the room treated now? I would also recommend getting those rugs off the wall if that is what I am seeing. You don't have much upper energy left in the room from what I can tell.
OK, carpets come down tonight and I'll retest one speaker at a time.

Thanks.

No treatment at all currently. Other than the , ahem... carpets. Yah, I know.
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30th January 2013
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Quote:
Originally Posted by DanDan View Post
Pretty bad I suppose, but compared to what? You will need a measurement in each of the possible locations. Then you will be comparing rather than asking to evaluate.
I guess my question has really changed. I think I've figured out that this is about the only practical mix location in the room - the only place I can get some symmetry at the mix position and be able to organize the rest of the room properly. Now I guess I'm looking for what problems I'm facing at that position and how I can fix them.


Quote:
Again, the RTA gives instant visual feedback while you wander about with the mic, and Jeff's reciprocal idea.
I'll see if I can figure that out. I wouldn't really know how to interpret that feedback yet, though. I'll have to figure that out too.

Thanks for the help, guys.

Incidentally, I just realized there were stickies at the top of this forum dealing with posting measurement info. I was just relying on Glenn's video, which is very helpful, but I'll go through the sticky threads in much more detail before posting additional results.
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31st January 2013
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Carpets are now GONE!



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31st January 2013
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And here are the measurements. I measured with left speaker, right speaker and then both together. Graphs show FR at 20Hz - 20kHz for each of left and right and 20Hz to 500Hz for left, right and both together, plus waterfall for each at 20Hz - 500Hz. I've also included IR's for left and right (forgot to save the one for both).

Even to my untrained eye, I can tell that I have some serious bass issues! Not sure what else.

So, what am I facing here?
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31st January 2013
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Just did a quick look so maybe someone else has a bit of time to spend on them but things seem to be matching up about as well as you can. There does seem to be some noise in the test, like over driving the speakers or pre. Not sure as I am a bit pressed for time. Needless to say I would move forward and start treating the room. Bass trapping with panels for early reflection points. You may want to thick about cornering all broadband absorption that is not in the early reflection points with a slat design to help scatter/diffuse/retain (non dead) upper frequencies in the room.
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31st January 2013
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Bass

Do you have an alternative viable working location. If so I would test it. One speaker should be enough to give an indication. Your current bass situation is dire, mostly due to BIR which will may not respond much to modal treatment.
I would rather see a better looking bottom end to begin with. Who wouldn't?...
;-)

I would prioritise LF evenness over symmetry any day. I mean 5.1 works well enough.

DD
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31st January 2013
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Quote:
Originally Posted by DanDan View Post
Do you have an alternative viable working location. If so I would test it.
The other possible locations would be along the north wall, probably positioned a bit to the west, or along the south wall, as was previously suggested. Neither of those are as symmetrical as being along the east wall, but I'll test in both of those spots and see how the LF looks. I'll also re-test using one speaker centred along the east wall, just so that I'm comparing apples to apples. Practically, I'm not going to be able to build walls to create more symmetry at that south location (as Syncamorea suggested). But if the LF looks really good there without the extra walls, maybe the trade-off is worth it.

I think I also may not have gain-staged properly. I likely need to turn my speakers up a bit and my mic pre down a bit. That might be causing the noise Glenn was referring to. I'll correct that.


Quote:
I would rather see a better looking bottom end to begin with. Who wouldn't?...
I'm more about a sweet top, but can't argue with a nice bottom.

Again, thanks guys! While my initial question was mostly just about moving my desk around, this thread has actually gotten me kind of excited about getting a new desk and treating the room properly to get all my acoustic issues ironed out (to the best extent possible anyway).
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31st January 2013
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Location

You will get a great start if you settle on the optimum locations, and vice versa.
Quote:
I'll also re-test using one speaker centred along the east wall
Rather than centred, I would place the speaker at it's very likely practical location.
i.e. as if the two speakers were there, spaced apart apppropriately.

DD
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Quote:
Originally Posted by DanDan View Post
Rather than centred, I would place the speaker at it's very likely practical location. i.e. as if the two speakers were there, spaced apart apppropriately.

Oh OK, I guess I don't need to redo that one for the east wall then. I already have it in the measurements I just posted. But I'll keep that in mind in doing the north and south position measurements.
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2nd February 2013
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Even though I said I had no "treatment" in the room, I realized after my last post that I had recently put a couple of office-divider type baffles up to control the levels of a drum kit when tracking. I've taken those down now and redone the measurements from three different mix positions. Wow! Even in my original mix position, the bass response of the room looks totoally different (to me) with those baffles gone.

Anyway, I'm going to post my three possible mix positions together with measurements. Please let me know if there is a clear winner among these three (i.e. a position that is either naturally pretty good or has problems that can easily be treated). As DanDan suggested, I'd like to get off to as good a start as possible before diving into treatment.

Here's the first option, floor plan together with test measurements (mix desk on east wall, where it currently sits - probably the most symmetry possible in this room)...

[DELETED]
Attached Thumbnails
How to Deal with a Room Where Symmetry is Impossible?-spl-both-speakers-position-1-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-left-speaker-position-1-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-right-speaker-position-1-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-both-speakers-20-500-position-1-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-left-speaker-20-500-position-1-.jpg  

How to Deal with a Room Where Symmetry is Impossible?-spl-right-speaker-20-500-position-1-.jpg  
Attached Files
File Type: wav both speakers (position 1).wav (384.0 KB, 5 views) File Type: wav left speaker (position 1).wav (384.0 KB, 6 views) File Type: wav right speaker (position 1).wav (384.0 KB, 4 views)
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2nd February 2013
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Here's my second possible mix location (mix desk on north wall - not very symmetrical)...

[IMAGE DELETED]
Attached Thumbnails
How to Deal with a Room Where Symmetry is Impossible?-spl-both-speakers-position-2-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-left-speaker-position-2-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-right-speaker-position-2-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-both-speakers-20-500-position-2-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-left-speaker-20-500-position-2-.jpg  

How to Deal with a Room Where Symmetry is Impossible?-spl-right-speaker-20-500-position-2-.jpg  
Attached Files
File Type: wav both speakers (position 2).wav (384.0 KB, 3 views) File Type: wav left speaker (position 2).wav (384.0 KB, 6 views) File Type: wav right speaker (position 2).wav (384.0 KB, 3 views)
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2nd February 2013
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And my third possible mix location (mix desk along the south wall - a bit symmetrical I suppose)...

[IMAGE DELETED]
Attached Thumbnails
How to Deal with a Room Where Symmetry is Impossible?-spl-both-speakers-position-3-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-left-speaker-position-3-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-right-speaker-position-3-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-both-speakers-20-500-position-3-.jpg   How to Deal with a Room Where Symmetry is Impossible?-spl-left-speaker-20-500-position-3-.jpg  

How to Deal with a Room Where Symmetry is Impossible?-spl-right-speaker-20-500-position-3-.jpg  
Attached Files
File Type: wav both speakers (position 3).wav (384.0 KB, 0 views) File Type: wav left speaker (position 3).wav (384.0 KB, 4 views) File Type: wav right speaker (position 3).wav (384.0 KB, 3 views)
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