Local Prices

samplesj · « **Reply #20 on:** 15 Feb 2006, 10:13 pm »

Believe it or not, the fiberglass wasn't really messy. I cut all of the fans off just in case, but once I got it out there wasn't really anything left in there.

I only had to open that one box to get it on the passenger's side. The box just wouldn't flex enough to fit in the door, but there was room inside so I put them in one at a time so I could flex it enough.

We've had it out a couple of times since then and haven't noticed anything yet. I did find two small scraps stuck to my wife's hair and back the first trip out, but this time of year everyone's got on coats so its not caused any itching.

klh · « **Reply #21 on:** 20 Feb 2006, 08:48 pm »

I went by the distribution center and picked up 4 packages of 2" 8# mineral board and 1 package of faced 2" 3# Knauf compressed fiberglass. I hastily put up two packages in the front right corner (so 8' tall) and one in each of the rear corners. The front left has nothing because there is a 3' wide opening in the corner (a space for a door but there is no door). Since it opens to a huge area (maybe 15,000 cubic feet), that should act as a bass absorber since it wouldn't re-enforce the bass.

As for results, they were immediate. I haven't measured the sound, but I think it's too much absorption. Since it would be damn hard to measure, I'd like your suggestions on how thick to make the 8# absorber in the front right so it mimics what is going on in the front left? Should I go 4", 6" or 8" thick? Having said that, how thick would you go in the rear corners? I think 4" thick floor to ceiling in the rear corners would be good.

The 2" 3# faced rigid fiberglass is for the wall/ceiling corners. I'm only going to have a ring of 1' wide panels up there. I'm not worried about extensive absorption... I just want to decrease the corner amplification a la 8th Nerve.

The didn't have any 2" 3# unfaced rigid fiberglass... I'll have to wait for their next shipment. BTW, I got much better pricing when I went in person. Although still high, it was $1.60/sf for the faced and $1.20/sf for unfaced 2" 3# material. It's the best pricing I could find, and I figured it was worth it since I didn't have much of an alternative.

bpape · « **Reply #22 on:** 20 Feb 2006, 11:27 pm »

Try to maintain symmetry left to right. Try 4" thick in both rear corners floor to ceiling with nothing in front first.

Bryan

klh · « **Reply #23 on:** 21 Feb 2006, 07:40 pm »

Guys,

Do you think this would work for covering the traps...

http://www.fabric.com/apparel-fashion-fabric-broadcloth-fabric-solid-cotton-broadcloth-fabric.aspx

bpape · « **Reply #24 on:** 22 Feb 2006, 03:02 pm »

For broadband bass control it would likely be fine. It's difficult to tell from a picture. If you can find some of it locally, pick it up, hold it to your mouth, and try to blow through it and see how much resistance there is. The less the better.

The things that are known quantities are:

Guilford FR701 and a few other Guilford families
Lightweight Muslin - easily available and cheap and can be dyed
Open weave Burlap - again easily available, less expensive and can be dyed.

lonewolfny42 · « **Reply #25 on:** 23 Feb 2006, 01:14 am »

Quote from: bpape

Lightweight Muslin - easily available and cheap and can be dyed...

...... lightweight cotton Muslin........

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samplesj · « **Reply #26 on:** 23 Feb 2006, 01:32 am »

I actually found some nice looking unbleached muslin at Wal-Mart. It has a sort of stone color to it.

klh · « **Reply #27 on:** 23 Feb 2006, 06:04 pm »

How do you color dye lightweight cotton muslin?

bpape · « **Reply #28 on:** 23 Feb 2006, 06:08 pm »

Good old RIT dye. They have liquid now that works pretty well. If you want a real dark color I think you might still have to boil it but normal colors can be done just in the washing machine.

lonewolfny42 · « **Reply #29 on:** 23 Feb 2006, 06:23 pm »

An example of a dyed cotton muslin fabric....if your artistic (those panel would really come alive...

)....

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klh · « **Reply #30 on:** 24 Feb 2006, 05:02 pm »

I went by Wal-Mart and saw the unbleached muslin (14.99 for 15 yds). I could breath through it, but it wasn't that easy. I wonder if it is wound too tight. I'm wondering if it would be better to just get the PE grill cloth (6.90 for 1-9 yds, $5.25 for 10+ yds). Since it's 70" wide, that's not bad, but a little more than I'd like to pay. Also, for the Rit dye, how much is needed? Their website said one packet will only dye 3 yds of fabric (and it costs $2.29). What is your exprience with them?

klh · « **Reply #31 on:** 24 Feb 2006, 05:20 pm »

Also, Ive put 4" 8# floor to ceiling in the back corners, I have 2" 8# temporarilly leaned up against the wall behind me and I have 6" 8# in the front right corner floor to ceiling. Remember there is a 3' wide opening for a door on the front wall all the way over to the left (3" from the left wall). Although that makes it impossible to put a bass trap there, I think it effectively acts as one.

The computer is at the opposite end of the house and it would be a royal PITA to move it to the theater room. I think I'll end up ordering a CD with test tones... any recommendations? I cheched out Ethan' test tones... they would be great, except my CD player doesn't play MP3s. Is there a way to convert them to a standard Redbook format?

Also, in the meantime, what option do you guys think would be theoretically better?

1) 4" in the back corners and 4" in the front right
2) 4" in the back corners and 6" in the front right
3) 6" in the back corners and 6" in the front right
4) 4" in the back corners and 8" in the front right
5) any of the above with the 8# laminated to 3# across the back wall
6) anything different you guys would recommend

I definitely like option 5), but I'd have to order more 2" 8# to pair that with options 3) or 4).

BTW, just 4" in the back corners was good, but the music sounds smoother with some in the front right ,too.

samplesj · « **Reply #32 on:** 24 Feb 2006, 05:35 pm »

Quote from: klh

I went by Wal-Mart and saw the unbleached muslin (14.99 for 15 yds). I could breath through it, but it wasn't that easy. I wonder if it is wound too tight.

I noticed that about the stuff they specifically called muslin locally too. I thought their specifically named muslin was more like the stuff I've seen used for kitchen straining. The cloth I found wasn't specifically called muslin (actually it didn't have a name on the label at all just the vendor and 100% cotton), but its a plain thin open cotton weave so I was using muslin generically (http://www.thefreedictionary.com/muslin'>definiton).

It was 2.27 a yard for 44" wide. Its not as cheap as I've seen some cloth, but my flooring and plant pots are all that same shade/texture so it was a great find for me. My next choice would have been what they called monk cloth at 7 a yard (much looser weave, but the other stuff was loose enough).

I wanted to stay away from dyeing because of the extra hassle/cost. If you are wanting black though I guess dye is hard to avoid. Maybe check out the black monk cloth, but it might be more than you can get the grill cloth from PE.

klh · « **Reply #33 on:** 24 Feb 2006, 05:44 pm »

I don't necessarily want black... I'm open to pretty much any color (well, maybe not pink). BTW, how safe is it to have uncovered mineral wool in a room?

samplesj · « **Reply #34 on:** 24 Feb 2006, 06:00 pm »

Quote from: klh

how safe is it to have uncovered mineral wool in a room?

Although it has been classed as a carcinogen in the past it is no longer
http://recording.org/ftopic-21013-0.html'>More Info

My bass traps are uncovered on the rear, but it isn't touchable. Even when I had the stuff crammed into the passenger's seat it didn't really leave much residue. To me it looks fairly self contained unless disturbed so really was only concerned about cosmetics.

Jeremy

bpape · « **Reply #35 on:** 25 Feb 2006, 02:39 pm »

Go find a JoAnn Frabrics store. The stuff you want - they sell for $0.99 per yard. Realistically, either will work fine as long as you're not trying to put it in front of a speaker.

klh · « **Reply #36 on:** 25 Feb 2006, 06:12 pm »

I went by JoAnns.. didn't get anything but will likely go back. I also downloaded Ethan's tones. I haven't ripped many CD's and the like, so I stumbled around a bit, but finally burned the tones onto a disk and they work wonderfully. Last night I turned it on quickly just to see how low my sub goes... I set the Pink Noise to 70 dB and I got all the way down to 13 Hz at 70 dB

. Couldn't hear a damn thing but it was pretty cool

. I'm going to get my wall/ceiling corner traps up before "dialing in" the vertical corners.

Guys... thanks for all the help

. I have to get the OK from the misses Re: fabric color so it may be a while

. I'll be sure to post pics and results when finished.

klh · « **Reply #37 on:** 27 Feb 2006, 06:37 pm »

Bryan,

I read somewhere that you sell foil/kraft scrim and that it can be adhered to non faced insulation. Do you recommend adhering it to 8# cross corner mineral wool broadband absorbers? I understand the ramifications... it increases low end absorption while increasing high end reflection. How much of a difference would it make? Since 8# material already reflects high frequencies (to some extent), and absorbs down low pretty good, I'm wondering if it is worth the effort. BTW, my traps are 6" deep.

Also, my room is 9 x 16 x 20. At this moment, I have the 6" deep 8# MW in three corners and an opening with 6" deep 8# above that in the other corner. I also have three 2" 8# MW boards laying against the wall behind me (creating a 6' x 4' mini wall of low end absorption). I had planned on having 2" 3# faced Knauf FG (but only 1' wide) across the wall ceiling corners (basically making a ring around the room). I'm wondering now if I should get two additional packs of 2" 8# MW and have six 4" deep 8# traps across the wall/ceiling corners. There would be 1 trap on each of the 16' walls and 2 traps on each of the 20' walls.

I took some measurements with just the floor to ceiling traps and I have peaks at 35Hz, 57Hz, 90Hz and 120Hz and troughs at 46 Hz, 78Hz, 110Hz. All of this is with the RS digital meter and using correction factors. The peaks and valleys are about 10 dB apart. I haven't gotte the chance to calculate if the 20' and 16' dimensions play into that, but I have a feeling they do.

bpape · « **Reply #38 on:** 27 Feb 2006, 07:43 pm »

It will certainly increase the low frequency absorbtion some but isn't likely going to fix your peak and null issues. Those are most likely related to a combination of seating position and speaker positioning.

Whether or not it's a wise idea will depend on how much other broadband absorbtion you have in the room and what else it needs. Realistically, if I were to guess, my suggestion would be a couple of 4" slabs on the back wall behind the seating but faced with the scrim. Lots of the nastiest nulls come from the back wall and are a function of the distance from your ear to the rear wall.

Obviously not all of them are from that but a combination of seating placement, speaker tweaking, and killing the back wall (as well as potentially shifting your whole setup and seat maybe 6-8" left or right from center should help significantly.

klh · « **Reply #39 on:** 27 Feb 2006, 08:06 pm »

Great! Thank you for you advice... you saved me a bunch of extra work. As I walk around the room when the test tones are playing, it's amazing how much it vaires from place to place. The saving grace is I'm the only one who understands and appreciates the difference... so if I fix my one spot, that's all that matters.