# Initial subjective testing of room treatments...



## boarder1995 (Mar 28, 2008)

Ok, I just received 8 2'x4' x 1-1/2" thick CertainTeed Acoustaboard Black series 300 (3 lb/cu. ft density) panels yesterday from FedEx and did some initial setup and listening last night. I didn't do any baseline measurements prior or post setup yet, so this is purely subjective listening and initial reactions to what I did and what changed. I also only changed the volume control while listening and took mental note of where I normally listen to certain recordings and where I was listening to them with the treatments. I did not change any individual speaker or sub trim levels at any point.

First off, I've got bi-polar speakers (Mirage 895is, front 1"/5.25" and rear 1"/5.25" speakers in each tower) and when subjected to absorption behind the speakers, obviously things are going to change dramatically! I've got dual SVS Ultra 13's in the front corners of the room (but not located directly in the corners). My room is all ceramic tile floor with a large area rug with no padding beneath it. The room is 15' wide by ~20' long x 10' tall. The back right corner of the room is a full opening about 10' wide, so there's not much back wall except a the non-symmetrical 5' in the back left. Furniture is all leather and we have a large-ish glass topped coffee table in the center of the room. I setup and level matched things how I like with REW and am familiar with its basic settings/testing capabilities.

The first image was the full setup with double thickness (3" thick) panels in each of the three corners in the room (rear not pictured). Also, a single thickness panel (1-1/2") behind each front main speaker.









I only listened to 2 channel stereo (with subs). Initially, I was amazed at the differences. Not necessarily for the better, but still amazed at how different it sounded. It sounded more muted, controlled, less harsh, quieter. Eventually I got somewhat used to the sound. Even turning up the volume way past what I normally listen to, my ears didn't complain.

After a good session on a variety of music (pipe organ/classical and hard rick live concert) I removed the treatments and re-listened. Wow, it was a fair bit "louder" to my ears and quite a bit more live sounding, but also very difficult to pick out instruments, and much more confusion. Certain sounds were harsh and with much volume my ears hurt.

So I re-enlisted some of the panels, this time strictly in the 3 corners of the room, double thick in each corner (3") and nothing behind the speakers.























This was not nearly the dramatic change I initally observed, but still discernable, but only in the bass region with very little change in the mids/treble. I only noticed the mid/treble difference when I once again removed all the treatments. Still the strictly corner placement was a good change. The bass wasn't as floppy, perhaps a bit more tamed. Initially, it sounded quieter in the bass region, but later it just seemed more clear. I listened through the entire live hard rock concert this time and eventually went from room treatment testing, to just enjoying a live concert. Music gets in the way like that sometimes.

In then end I don't know if the WAF will get to where it needs to be for anything like these to stay. I've got a week of her on a business trip to do some panel cutting and covering to better fit in the room. Before I do that, I'll try to get on the ball and actually take measurements to best determine what I need and what I like. I've also got some friends that'll come over for listening help. We'll see where it goes from there!


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## Prof. (Oct 20, 2006)

I would also suggest that you try the corner traps at 6" thick..
This is the normal recommended thickness for flat corner panels..


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## boarder1995 (Mar 28, 2008)

Ok, I'll try that, but what about splitting the 2'x4' panels lengthwise so they are 1'x4', thus I'll have more to make thicker corner pieces, plus they'll nestle into the corners better? I may even have to go narrower to even think about keeping them in the room. I know this will lessen their ability to dampen bass, but if they're adequately thick and tall would this be a good trade-off?


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## eugovector (Sep 4, 2006)

If you're going that route, you should look at superchunk bass traps, ripping each 2x4 into 8 triangles and then stacking those in the corner. They'll fit a little more snug and will perform much better.


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## Prof. (Oct 20, 2006)

eugovector said:


> If you're going that route, you should look at superchunk bass traps, ripping each 2x4 into 8 triangles and then stacking those in the corner. They'll fit a little more snug and will perform much better.


Agreed...Cutting them down to 1' wide will reduce their effectiveness considerably..
Ideally they need to be as wide as practical..
Superchunks will do the trick..


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## boarder1995 (Mar 28, 2008)

Great suggestions, plus they'll have a better chance passing the WAF. Ok, so a stack of progressively larger sized equalateral triangles to nestle into the corners. Make them ~6" thick still? I'd like to use a few (3 of them, perhaps full size) on the front wall stood up behind the mains (L/C/R) possibly. Corners first! I'll be able to do the lower ones, but also should try the upper ones to? Thanks guys.


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## eugovector (Sep 4, 2006)

Nope, like this: http://forum.studiotips.com/viewtopic.php?t=535


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## boarder1995 (Mar 28, 2008)

Ah, ok. I'd have gotten there eventually by SEARCHING! ;-)

So, what about GIK's smaller 3 wall interface corner traps? The ones that are equalateral triangles and sit up or down at the interface of a 3 wall junction. I'm reading about the superchunks...might need more material.


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## eugovector (Sep 4, 2006)

GIKs products will work and look great. And yes, if you DIY, you'll need more material.


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## boarder1995 (Mar 28, 2008)

I have another question regarding the corner solutions (StudioTips Corner Absorber and the SuperChunk). It's mentioned that the trap should be against the walls...
"When mounting the panel be careful to fix it into the corner so the both long backside edges touch the room boundaries [walls, ceiling or floor depending on how you orient the panel]. Gapping the panel away from the walls as little as a couple of inches will make the 100 Hz peak demonstrated in the "4 Devices" comparison collapse."
Now in my front two corners, I've got an extra protruding corner (see photos up top). Will this perhaps help my standing bass waves and make front bass traps less necessary - kind of like a diffuser? It'll require a bit more of a custom solution if I do place a trap up front. I took some REW measurements without any room treatments (a while back) and I don't seem to have too much room ringing going on (posted graph in REW forum) I believe.

Now in the back of the room, I've only got one corner, the other is a square column support that is open to two story cathedral cielings for the rests of the main area in the house. So, I'll likely do well by treating that one rear corner I do have.


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## eugovector (Sep 4, 2006)

You can't practically diffuse bass frequencies, the waves are far too long.

Also, don't forget you have corners where the floor and ceiling intersect the walls. These may be a preferable place for you to trap, just below your cabinet doors. You could also build custom panels for the back 4-6" of those 2 insets to either die of your TV.

Other than that, your front wall doesn't have a lot of opportunities for acoustic treatment. If you don't have much ringing, focus on your side wall/ceiling reflections, in addition to what I've already mentioned.


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## boarder1995 (Mar 28, 2008)

Ok, so no diffusing bass...that sounds more logical. First reflections and mid/treble dampening seems to help make my room less harsh currently with moving these 2'x4' panels around.

On another note (low ones specifically), I do notice in my front corners, more forward than my side located subs (basically behind my mains), there is a severe lack of bass. I put my head down near the floor in the corner and notice almost no bass. Now, I don't normally listen to my music while lying _behind_ my main speakers with my head in the corner, but this got me thinking about bass traps up front. If I can't hear an increase in bass volume in a location along a wall or in a corner, does that correlate to perhaps not needing a bass trap in that location or its effectiveness if placed there? In other areas of my room along a wall or near the back corner, I can hear an increase in bass. I know this is common and thus why it's recommended to avoid seating along walls. So what about the front lack of bass and the need or no need for bass traps in those areas. I'll experiment with measurements and listening once I place some of these superchunks I'm about to cut, but wanted to get some theory regarding what I'm hearing versus standing waves and corner issues. Thanks.


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## eugovector (Sep 4, 2006)

Okay, I'm officially out of my depth here, so hopefully someone else will jump in, but in the meantime...

Bass waves radiate fairly omni-directionally, so bass waves are definitely hitting that corner. If you're not hearing any bass, however, it's likely because the reflections are canceling each other out at that particular place (creating a null). However, those reflections at another place in the room, like your listening position, may end up reinforcing each other and creating a peak instead of a null (neither of which is desirable). So, you want to reduce reflections in that corner regardless.

Once again, just miy understanding, which could be wrong. Anyone else?


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## boarder1995 (Mar 28, 2008)

That makes sense, the waves would still be there as bass is omni-directional and corners, particularily tri-corners, are the most troublesome. Man, from y'all here to an abundant amount of info on the internet regarding studio setup, etc., I'm getting an education! I'll be treating with short superchunks initially all corners of the room. If those pass WAF muster, I'll perhaps expand those superckunks to go the full height in the rear corner that allows it. I'm not sure what to do with the coves, if anything at this point. Those are a great visual lighting focal point in the room my wife likes, so I'd perhaps be best to leave them alone.

Ok, another bass question, does the corner trap (trihedral corner) have to actually reach all the way into the corner? I see some trihedral corner traps that are fairly thick, but don't extend all the way into the corner. The same for linear two-wall corners - what's the rule of thumb here?


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