Roomus Horrendus!

**antoniod** · **03-06-07, 10:08 AM**

Hi folks,
I've been reading some things from multiple sources nevertheless I'm trying to get things clearer for me and need advice to try to take the right decisions.

Like many of you I'm determined to treat (at least to some extent) my listening (also living) room. I've delayed this many time, but few weeks ago a friend o mine lend me only a couple of commercial Tubetraps and :holycow: gotta have it!

The result of course...

These commercial treatments here in Portugal are extremely expensive and commercial abroad solutions become even less attractive due transport and import taxes costs, I'm going for the DIY route. So here am I.

For my room check the attachment. Those are the potential treatments (eventually others recomended) to build plus the ceiling wich are not reflected on this layout and still dont know exactly what to do.

To start the questions, I have some types of materials that I have access to and I need some help to decide on where to use what. My goal is performance despite I might have space, budget or other constraints. But for instance if one solutions is more expensive than other and considering there are no other constraints if it's better I might choose it if it's still affordable, so let's start with the materials...

Panels of Mineral Wool available
Density (kg/m3)-Thickness(mm)
40-30
40-40
70-30
70-40
40-40 (FRK)
35-40
90-30
90-20
100-30

For the two front corners due aesthetic reasons I prefer the superchunck type bass trap, nevertheless let's keep the options open for now.

Superchunk - From what I've been reading it might not worth use more than the 40-40 panel, it would be more cost effective and performance would remain good, as opposed to using the 70-40 panel.

Bass trap 4" or 6" (still in the corner) - 70-40 material would probably be a better choice and the higher cost of the single panel is compensated by the fact less panels would be necessary.

Performance wise. Imagine both previous types with the same height, width (within the corner or stradling). What would be the more efective? Is there a way to knowing it without building and measure them?

For Bass traps of panel type is there an advantage in mixing diferent densities within?

By the way, despite I have measured my room recently with REW but now I have new speakers and response it certainly will have changes. One thing I think is going to change (but it might take a while... an ethernity!) is the bass response of the speakers because that woofers are really stuck at the beginning! Do you think I should wait or move onto the room treatment?

Despite I still didn't had the time to measure with REW again I did a fast check with a tone CD and it's obvious that that peak at 40Hz is still killing me (of course the room didn't)

, 20dB's beyond reference tone!!! See my back wall and please comment.

Room is around 6mx4,4m,2.7m concrete walls with tiles(just hate them

) till 90cm high!

See the attach for my room and feel free to comment...

thanks,
Ant

PS: Just a word of appreciation for the moderators of this section which play a great service to the community here as well as some of them out of here for the community worldwide and of course all the forum members. To you all a great

**Ethan Winer** · **03-06-07, 11:48 AM**

Ant,

My main suggestion is to rotate your setup so the loudspeakers fire the longer way down the room. As it is now, sitting right in front of a wall, you're in the worst place you could be. That's where the inevitable peaks and nulls are worst. Much better is to have the wall behind you as far back as possible.

--Ethan

**antoniod** · **03-06-07, 11:55 AM**

Ethan, appreciate your suggestion but unfortunately can't do that! In the sketch it seams big but on one side the firewood on the other the door, so this is what's possible.

**bpape** · **03-06-07, 12:36 PM**

Just remember that if you have enough material to go 6" thick, you can get the same height as a solid 17x17x24" triangle.

Pulling the seating away from the rear wall a little will help minimize the modal activity throughout the spectrum. Even after that, I'd throw a nice slab of absorbtion behind the couch on the floor - as big as you can get away with. Also absorb on the wall behind you. You can try a slat resonator but with no more broadband than you'll have in there, I think the other would be preferable.

Bryan

**Ethan Winer** · **03-07-07, 10:49 AM**

Quote:

antoniod wrote:

unfortunately can't do that!

In that case you need thick absorbers to work well at low frequencies, but that are also effective at mid and high frequencies. Peaks and nulls are always worst right at a boundary, and absorption is the best cure for that.

--Ethan

**antoniod** · **03-08-07, 04:19 AM**

Quote:

bpape wrote:

You can try a slat resonator but with no more broadband than you'll have in there, I think the other would be preferable.

Bryan

Bryan, I'm not sure I understood you there, could you please rephrase the sentence.

Behind the sofa I could build on the floor a superchunk bass trap type also, is that what you meant? Besides panels I intend to put behind my listening position.

Ethan, you're absolutely right. Just by moving forward my head during listening session where I was clearly hearing a big peak it was at a minimum, attenuated.

Anybody would care to comment my question about materials density and it's usage...

Thanks,
Ant

**bpape** · **03-08-07, 06:13 AM**

Yes - that was my basic suggestion. I was also suggesting that the absorber on the wall behind your head might be better as a broadband absorber also.

The choice of materials is OK.

Bryan

**antoniod** · **03-08-07, 08:30 AM**

Thanks Bryan, clear now!

**antoniod** · **04-03-07, 06:54 AM**

Hi,
finaly had some time to start the experiments this past weekend.

Just did some mineral wool cutting (what a pain in the a$%!) and start building the front superchunks.
Besides, I have just grab some panels without structure and place them beyond the speakers, and some beyond the sofa with less than half a meter above my head (so not the exact location they will be).

Didn't had the opportunity to make some measures but the diference is huge and it promises outstanding results. Nevertheless despite I like a lot the result I'm afraid I would make the room too dead. Why, because I'm not even close to finish the room and the diference was so big in perception. Ok, I admit I'm probably still getting used to this new sound (or lack of it

) because my room was too much alive. I remember some months ago taking measurements of RT60 and it was the double it should!:raped: Something like .8 and it should be something like .4. or .3.

If in front of the superchunks I use a panel with FRK turned to the room would it be ok? This way as far as I understand mids and highs would be reflected and bass would still get traped.

Other question is, what spacing should I use between the traps (beyond my speakers) to the wall those traps are 12cm thick. I think I read somewhere the spacing should be the same of the thickness for best results. Can anybody confirm this?

The only bad news is (based on fast 1/3 octave tone cd) that hump around 40Hz is still killing me.

But now earing a double bass is something nice

thanks,
Ant

**antoniod** · **04-05-07, 11:27 AM**

I guess I'm making difficult questions!

**bpape** · **04-05-07, 12:21 PM**

The hump is probably a combination of not enough bass control and a seating position issue.

If you're going to use FSK facing on some of the bass absorbers, use it on the ones in the rear - leave the front broadband.

As for the side absorbers, the distance behind is to maximize low end absorbtion - assuming there is a bass buildup problem where you have the panels.

Bryan

**antoniod** · **04-09-07, 04:58 AM**

Quote:

bpape wrote:

The hump is probably a combination of not enough bass control and a seating position issue.

If you're going to use FSK facing on some of the bass absorbers, use it on the ones in the rear - leave the front broadband.

As for the side absorbers, the distance behind is to maximize low end absorbtion - assuming there is a bass buildup problem where you have the panels.

Bryan

Hi Bryan,
Still have to try a little different seating position but it's not easy to move those speakers from their place!

Just to check if I understand, when you mean front, you mean the wall where the speakers are, correct?

Ok, I understand the distance is to maximize low end absorbtion, but the question was, is there an optimum distance (and I was mentioning also for the traps beyond speakers to minimize the SBIR issues)? I guess there is for a particular frequency but not for the others, correct?

thanks, once again!

Ant

**bpape** · **04-09-07, 06:08 AM**

Front is behind the main speakers - yes.

For absorbers to deal with SBIR, they need to be directly behind and directly beside the speaker - distance matters not. It's killing the spherical wavefront that is bouncing off those surfaces and coming back to mix with the direct speaker signal causing the positive and negative reinforcement.

Bryan

**antoniod** · **05-10-07, 04:21 AM**

Hi again, time for the acoustics hasn't been much, but I'm in the process of taking some decisions, so I would appreciate some comments again regarding the way to follow.

For the traps behind the speakers I'm going to build them with 12cm thick, however for the size of them I don't kow what would be the best, I can use panels of 135cm or 120cm (or cut the 135 to 120!) and I was thinking in build two traps of 120 and place them on top of each other to full fill the 240cm behind each speaker. My ceiling is at about 252cm.

Or should I just place one of 135cm behind each speaker? What approach would have more benefit?

My speakers are these http://www.accusticarts.com/pages/en/concerto_fr.html

thanks,
Ant

**bpape** · **05-10-07, 06:08 AM**

One 60 x 120 should be of sufficient size. One behind each speaker starting at basically floor level will be fine.

Bryan

**antoniod** · **05-10-07, 07:16 AM**

Forgot to mention that the speaker contains 3 ports on the back, please click the "further details" link on the previous web page link address to check for the speakers construction.

Do you still think it would be enough?!

Should I make it thicker? In fact I was thinking in making it a little wider...
I did try to put the panels just in place 60x135 on the floor level, didn't do any measurements but I really liked what I eard!

Thanks a lot!

Ant

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