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 Acoustic Panel 

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The Elegant and Affordable Audiophile Tweak

Hear what other people have to say:

"Can I just say your a genius.  My speakers sound a lot better.  The highs are of course lower in volume now, so it now matches the rest of the spectrum.  Now the music doesn't sound muddy at all." - HTF member

Purpose:  Acoustic Panels absorb sound waves from the high frequencies, to upper bass notes near 80hz (depending on materials, size, and placement).  Panels can also improve imaging by reducing reflected sound from walls.  At a DIY cost of $70 (or less) for four 2'x4' panels these can be a worthy investment for improving sound in your listening room and/or home theater.

Test your room by clapping and listening for echoes.  If you noticed your room sounds close to a tiled bathroom then these panels may be for you.

Back View

Side View

 

As for the materials list, I purchased extra with contingency in mind.  (room for error)  Below you fill find the exact numbers for what I used to build 4 panels.  In addition to those materials I used some WIRE, and wood GLUE.

Of course you can build your own custom versions, and it would be easier to make a 17" wide panel and not a 24".  But, I let Home Depot do the cutting and decided to do this one without a shop and in my garage. 

Key Benefits

bulletReduce reflections to improve soundstage and stereo imaging
bulletLower ambient room noise to improve clarity
bulletMake bright speakers warmer sounding and less fatiguing
bulletReduce slap echoes

Description

Approx. $16 Per Trap DIY

Quantity: 4 Acoustic Panels to be placed in key "mirror" reflection locations of the room

Dimensions:  4 feet high, 2 feet wide, ~4 inches thick with a ~6 inch bulge in the center.

Weight = ~15lbs fully assembled

Color = White Burlap

Flame Retardant = None added

STORE MATERIAL Quantity Unit Cost per Unit Total Cost
Home Depot Fiber Glass Insulation 3.5" thick.  15" wide by 32' long roll (R-13) 2 EA $8.80 $17.60
Home Depot Standard Peg Board.  8' x 4' sheet cut into four 4' x 2' sheets at store 1 EA $7.98 $7.98
Home Depot Wood 3/4" thick x 3.5" wide x 8' long.  (cheapest white wood found) 6 EA $2.16 $12.96
Home Depot 200 count White Thumb Tacks 1 EA $2.63 $2.63
Wal-Mart Yard of Burlap 7 YD $1.48 $10.36
Wal-Mart Yard of Polyester Batting (48" wide) 5.3 YD $2.27 $12.03

Grand Total 

$63.56

 

Directions:

Misc. Tools used:  Hammer, Drill, Tape Measure, Saw, Clamp, and Scissors.  (Home Depot cut the pegboard for free)

Hit Counter "Hit me baby one more time"

Figure 1

I used a hack saw to cut the support beams to match the pegboard.

  1.  Lay down the pegboard fuzzy side up.  This is so the poly batting will stick to the fuzzy side of the board and won't slide around.  (Figure 1)

2.  Cut the wooden beams so that the longest length goes all the way to the edges of the pegboard, and cut the short beams so that they fit on the pegboard..  (Figure 1)

3.  Mark and Pre-drill into the long boards so that you don't split the wood.  When gluing, make sure the marked side gets the glue on it so the nail goes into the other board centered.  There are also other options such as buying some framing brackets to make a stronger joint.  (Figure 2)

4.  Glue and then nail the frame together.  Make sure that the side that meets the pegboard is flat because cheap boards  vary in width slightly due to the rough cuts.  I'd clean up any seeping yellow glue with a wet rag.  Another option is to use screws and finishing washers to secure the pegboard but again, that is a little more work and money but stronger in the end.  (Figure 3)

5.  To attach the pegboard I used yellow glue along with steel wire I twisted and then trimmed.  I then used a hammer to bend the twisted knob down into the panel.  (Figure 3)

6.  Cut the polyester batting to length size (about 4 feet) and then I cut the width of it in half because my batting was about 48" wide.  The batting sticks to the fuzzy pegboard and the insulation will stick to the polybatting.  The polyester also acts as a filter to keep the fiberglass particles in the panel and not in your room.  (Figure 4)

7.  *Remember to use protection when working with fiberglass, I used a mask, gloves, and goggles.  It's not deadly, but can cause some itch.

Then cut a layer of 3/5" thick insulation and layer it on top of the poly batting.  This will only partially cover the width of the panel so you will need to cut another in half as seen in (Figure 5).  Once you've layer down one 3.5" thick fiberglass you then layer another 3.5" layer except this time you place it differently as seen in (Figure 6).  Notice how thick the panel seems to be, make sure you push down on the edges so that they are somewhat inside the panel.  Last, put the left over layer you cut of the poly batting on top of the panel.  You will now have a sandwich which goes:  (from bottom to top):  Pegboard, polyester, fiberglass, fiberglass, polyester, (and then burlap).  (See pic 3 in Figure 6, See Diagram for Sandwich)

8.  Now for my favorite, part.. the squish and tack.  You are going to flip the panel and center it onto a single burlap sheet which rests on the (clean swept) ground.  Then add a heavy weight on top of the panel as seen in Figure 7. 

You will then push down on the middle so to help squish some more, and tug the burlap on all edges before tacking to remove any wrinkles.  Keep in mind that in my case, the frame still didn't touch the ground all around because it was pretty stuffed.  When you tack, I pushed in with my finger, and then touched it with a hammer.  It goes into the pegboard nice and strong though I did bend a few tacks.

9.  My special folding technique is shown in Figure 9, and you can also see how I tacked.  I started with the middle, and then the ends.  After I added an in-between, and then another in-between.

10.  FINISHED...  Now that you've seen the hours it took for the panel you can now enjoy absolute ambient noise suffocation.  Just choose a way to install them by either hanging them using eyelets, or making legs, or just plain mounting them on the wall.  Keep in mind the further you space them away the better the bass absorption.  3-4" would be plenty, especially if you plan on building DIY bass traps or helmholtz resonators to control the bass frequencies.

 

Figure 2

I pre-drilled a 7/64" hole for a 1-1/4" nail -- 11ga (Bright Hoist Hanger)  

Figure 3

I used galvanized steel wire along with yellow glue.  

Figure 4

Cut poly batting and line bottom.  

 

 

Figure 5

Cut Insulation and add the first layer on top of the polybatting.  

 

 

Figure 6

Add one more fiber glass layer, and then a layer of polyester batting.

Diagram

 

 

Figure 7

Flip onto burlap (approx 5 feet) and then add weight to squish the insulation down.

 

 

 

Figure 8

Stretch and tack, start with sides, and then top bottom.  I tacked middle first and then outer edges, then the in-betweens.

7 taks on top/bottom, 9 tacks on sides.  Out of 200 tacks that leaves 78 to bend.

 

Figure 9

The quick fold and tack shown here.

 

FINISHED

 

Lightly sweep or vacuum the burlap and you're ready to install them.

Installation

I hung the panels 4" spaced from the wall with wire from the Ceiling using 50lb EZ-Mount Drywall sockets that I first screwed into the ceiling drywall.  Hook screws then went into the ceiling sockets, and wood frame of the panels.  Last, I twisted loops on the ends of equal length wire and they are now suspended from the ceiling.  See Diagragm on the left.  It was about $2 for four drywall mounts at Home Depot and $4 for a box of "Hook" screws.

The Test and Review

Test 1

In this test I spaced the acoustic panel 4 inches from the wall and suspended it from the ground about 2 feet.  The speaker and the SPL meter form a perfect 90 degree angle at the center of the panel as shown.

With no panel at all, the bare wall reflects just about everything that's sent to it producing 70db of white noise.  Then when I just added the acoustic panel, the reading ended up with an immense drop of 13db all the way to 57db.  To see if my 4" thick foam panel (egg crate open cell) could do any better I then took measurements with it as a direct replacement for my panel it and it read 63db which was only a 7db drop.  (Still a lot better than a plain wall)

Test 2:

This test was the same as the first except it involved mostly direct sound.  The conclusions were basically the same in that the panel performed better than the very thick foam, and it certainly made a big difference from using nothing at all.

 

The tests were done with white noise emanating from a single floor standing loud speaker (40-20khz resonse).  In case you don't know what white noise is, it sounds like the static noise you get when TV reception is bad.  This was all done in my room which had the other 3 panels already installed to help reduce some of the unwanted reflected noise that may affect the test. 

Conclusion: 

The sound stage has often played a minor role in the enjoyment of music.  That is until I discovered a way to drastically improve upon it with the use of these acoustic panels.  One of the major breakthroughs the panels has caused is an incredible separation of the music in the soundstage.  Rather than having sound coming from 3 localized points across the horizontal sound stage,  the sound now appears broken up into at least 5 sections where sound can easily be focused upon.  Noises that were once localized at the speaker are now sounding about a foot closer to the middle.  This has not only made the speakers more transparent but has helped create a better image of wide sources such as the sound that comes from drum sets.

The second impact the 4 panels have created is the immediately noticeable drop in ambient noise.  Not only does my small room sound much bigger, but it also passes the "clap test" with flying colors.  The room is now the quietest room in the house which has become very popular with my two dogs who seem to love the comfort of a room in which they can almost hear a pin drop.  Yes there is still a slight trace of a slap echo, but most of it seems localized high near the ceiling.  Another test I used for evaluating the acoustic change was the whisper test.  I moved from big room, to small room, to my room whispering loud and soft, exaggerating "s", "sh" and "t" noises.  The conclusion I had was that the new room greatly reduces the amount of high frequency vocals making my whisper clearer to understand.  The bathroom was of course the worse at this test as the reverb greatly clouded the details in voice.

You can tell from the tests that these panels greatly perform better than thick open cell foam and can have a huge impact on the reflected sound.  Now just imagine how much 4 of these panels at the major reflection locations will sound different than the just the plain walls.  The principle is simple in that it reduces reflected sound from walls therefore making the sound you hear more of the direct sound that comes from a speaker.  It is taking your room a step closer to anechoic, just without the acoustic suffocation in the mix.  Every person that has listened to "before and after" music in this room has noticed a difference.  Even my 14 year old sister can tell that my room is easily the "quietest" in the house and music just sounds better.  Of course not everyone's taste for music is alike and there could be people who enjoy the reflecting sounds of of a specific room.  Then there are others who enjoy diffused sound which would be a more difficult DIY project.

May I mention these have little to no effect on any bass frequencies below 80hz as the deep test tones were not affected by a single panel whatsoever..  However, If you end up building these please email me with your results and include your room size and number of panels, etc.  I will gladly add your quote to this page in hope of it to help convince people how much acoustic treatments can really help. 

Other popular materials related to acoustic panels:  Compressed Fiberglass, Rock Wool, Sound deadening board, Polyester, open cell foam, and carpet.

Chris Tsutsui  Oct. 26 2002

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Pricing

Description SKU # Price
  sku-bt1 n/a
  sku-bt2 n/a
  sku-bt3 n/a

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Copyright 2003 Chris Tsutsui
Last modified: 06/25/03