Author Topic: "Soundproof" Partition  (Read 16843 times)

Offline richidoo

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"Soundproof" Partition
« on: January 24, 2008, 05:07:43 PM »
I want to make a sound attenuating partition to block out some of the reflections from the kitchen behind my listening seat. It will not be totally sealed off because there is a 5' wide walkway connecting the rooms which can't be sealed. But there is a half wall about a foot behind me, and I want to place an accordion wall on top of it to attenuate some of the dirty cold sounding reverb from the kitchen. 

It was suggested by my wife and a couple audio friends to just hang curtains. But to me curtains will look weird, especially the variety thick enough to attenuate sound. Thick shiny velvet curtains hanging in there would look too freaky. I figured out a way to mount an accordion wall so it hides up against a corner kind of unobtrusively, I think.

I'm concerned that cutting the 39 foot length in half with a wall might screw up the decent bass response I have. I guess if it is not reflective then it shouldn't be a problem. Is 1/8" mass loaded vinyl sheet reflective to bass? Does it matter??? :)

I was thinking of making the panels about 2" thick, with a sheet of vinyl in the middle, and 1" rigid fiberglass on either side of it. 6 hinged panels will cover the 126" span. Felt pad to slide on the top of the half wall. Maybe a brush at the top to seal the ceiling a little, but probably not necessary.

What can I use a mask to prevent it from sounding too dead, so close to my head?

I'm sure there is a better recipe for a thin attenuating wall than my first uneducated guess. Maybe it can be thinner, maybe I don't need or want vinyl in there. Any and all advice, opinions, and wise cracks are all mucho appreciatos.
Thanks!
Rich
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline bpape

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Re: "Soundproof" Partition
« Reply #1 on: January 24, 2008, 05:54:49 PM »
Hey Rich.

Just be careful putting any kind of mass there.  Your seating is very close to that short wall.  As soon as you put something there with mass, you'll get bass buildup.  If it was me, I'd likely do the curtain thing but get something you can sew a lining in and use limp mass vinyl in the pocket for the lining. That will damp things but not allow the bass buildup.

Bryan
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Offline _Scotty_

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Re: "Soundproof" Partition
« Reply #2 on: January 24, 2008, 07:28:17 PM »
My advice would be to cover the windows in the dining room with fairly heavy drapes that you can close for critical listening. You avoid standing waves and the problems they cause by as well as near field reflections from a partition behind your listening seat.
Scotty

Offline richidoo

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Re: "Soundproof" Partition
« Reply #3 on: January 25, 2008, 04:32:11 AM »
Thanks guys.
Bryan, you mean this stuff sewn into or hung with the curtain? Blackout curtains come with vinyl sewn in, also claim to be sound deadening for noisy streets, but that thin white vinyl is much thinner than the 1/8".

So 1/8" LMvinyl will not stop bass? Attenuation curves for it seem to say not much attenuation in bass freqs. That's good.

Scotty, she only wants a topper on that window. I would put FG across the whole ceiling if I had druthers.
Thanks
Rich
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline Carlman

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Re: "Soundproof" Partition
« Reply #4 on: January 25, 2008, 05:17:33 AM »
I like the accordian wall idea but nothing like the kind I've seen in community centers or commercial applications.

I have an oriental screen I modified that you can try to see if it is close to what you want to do.  If so, maybe we could build something interesting and that looks good.

From a design perspective, I'd rather see a flat surface across that wall rather than wavy like a curtain.  I like the idea that it can hide away also... but it needs to look good either way.

So, while the screen is not in use, it could be behind what looks like a little pantry on the wall.  When in use, it can look like a straightened out oriental screen, with about 7 or 8 1" thick 'panels'...

My screen is your screen. :)
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Offline mdconnelly

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Re: "Soundproof" Partition
« Reply #5 on: January 25, 2008, 06:32:22 AM »
Rich, I've got a similar problem in that my living room has a large archway joining the dining room which has very large glass windows.  While I decided to not block the archway, I did put up double-cell cellular shades (accordian-type) over the windows that made quite a big difference.   They're top-down and bottom up, so it's real easy to open fully, open partially and fully close as needed.    I wonder if that would work for you?   Might be less obtrusive when you want it fully open, and very easy to fully or partially close while creating a non-reflecting surface.   They come in single, double and triple cell with different weight materials.  Just a thought. 

If you're not sure what I'm talking about, check out justblinds.com or selectblinds.com and look for cellular shades.


Offline bpape

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Re: "Soundproof" Partition
« Reply #6 on: January 25, 2008, 06:36:18 AM »
A lot of the ringing you're getting is going to be from say 400Hz up.  The vinyl will help with that.  What it won't do is form a hard rigid flat boundary to allow modal activity and bass buildup.  It will actually 'move' with the wave and dissipate some of the energy.

I was thinking of something that was sewn into the fabric so that it looked good on both sides since they're both highly used living spaces.

Bryan
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Offline richidoo

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Re: "Soundproof" Partition
« Reply #7 on: January 25, 2008, 07:35:30 AM »
Mike, that's exactly what stereofool suggested a few months back, cellular shades. Thanks for reminding me of that good idea. Not sure momma will go for the control rack mounted across the ceiling, and a little pricey for 126 x 76 coverage with a quality brand. But simpler than building something.

Vinyl sheet gives very high attenuation on midrange like Bryan suggests, so I am leaning strongly towards trying to incorporate that into panels that I can slide away. If I use pin hinges on the wall end I can remove the whole system for hiding easily. Otherwise I would leave it on the hinge folded away ready to use easily.

I already have a mechanical plan to make a folding panel wall with 6-7 panels ranging 14-20 inches wide. It is designed to fold away into the corner on hinges. I can use up to 2 inch thick solid panels and still not be too obstrusive. From what you guys are saying, I think maybe 2" thick might be overkill since complete soundproofing is impossible with the hallway gap leaking sound anyway. If I could get >30dB attenuation I think that would be enough to stop the kitchen reverb from distracting from direct sound.

Carl, now you can use that rice paper screen to enjoy silhouettes in your bedroom, as it was intended!
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline bpape

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Re: "Soundproof" Partition
« Reply #8 on: January 25, 2008, 10:03:25 AM »
You're not going to get 30db- sorry.  That takes a wall or a solid core door.  Anything that will give you that kind of reduction is going to be massive enough to cause the bass anomolies we're trying to avoid.

Bryan
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Offline richidoo

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Re: "Soundproof" Partition
« Reply #9 on: January 25, 2008, 10:56:30 AM »
Well, I guess I mean just noticing the reduction in reverb. Whatever that is in dB.
Thanks Bryan
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline richidoo

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Re: "Soundproof" Partition
« Reply #10 on: October 05, 2010, 08:51:13 PM »
Pulling one out of mothballs... Only so Bryan doesn't say "Rich is just a big talker... " ;)

I built the doors with pine boards and hardboard, screwed one to the wall with some small hinges. This is about a year ago. Shane took a look and said, no way man, those little hinges will not hold up 6 doors. So eventually I redesigned the whole thing with a real budget so I could buy some good folding wall hardware and do it right. This is what I am using. http://www.johnsonhardware.com/100rd.htm Very nice quality, and a decent price. I got the track in two pieces to avoid shipping by freight. I just shimmed the ends to meet perfectly. The total span is 126 inches. The doors are 22 inches wide, so the hanger is at the center point to balance the doors so they will open very easily. You see the gap at the end of the track, the glider bearings only need to get to 11" from the pillar. The gap I will fill with a block of wood. The ceiling is not flat in those last 4 inches, so the track had to stop short. No biggie.

It took a while to design this one, because of the complexity, and the tolerances. Big doors 2' x 6' that have to glide 1/8" away from a wall for 10' distance, then seal shut with very little leakage. After a couple weeks the CAD was finally done, I started cutting parts yesterday.  YAY!   :D

Of course, the joist I need to hang the system from was 3.5" away from where I needed it. So I made a header board out of my secret stash of rock hard baltic birch plywood to transfer the load of the wall to the joist. I have 2.5" screws every 8" and 3" of cantilever on the other side of the screw line to prevent bending of the screws, so I hope it's strong enough. The doors aren't so heavy, it should be fine. (Famous last words....)

Here is a picture of the track bolted to the headerboard.


Tonight my wife and son helped me on the table saw to dice up a full sheet of plywood into 2" strips to make all the door frames. My wife was holding the outfeed, and clouds of sawdust were billowing all over her. What a trooper. My son ran around turning the saw on and off and helping to line up the cuts. My younger son wanted to help earlier in the afternoon but the plywood was too heavy for him to handle by himself.

It is midrange noise that I want to attenuate from the kitchen, hums and motor noise from appliances. But most important is to get rid of the midrange echo from the music system bouncing back from the hard surface kitchen. They will be stuffed with 2" OC703 FG. The side facing the music room will be hardboard with a section of goodpanel at the bottom. I don't want any absorbtion that I don't need. I like a live room as long as it's not out of control. I still need to hang curtains for lonewolf, so that will add some tame. The side facing the kitchen will be thin plywood all the way. Both sides will be painted, but not in time for the G2G.
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline Werd

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Re: "Soundproof" Partition
« Reply #11 on: October 05, 2010, 08:55:46 PM »
I would just bare with it, you are not going to be able to anything without making it look real oddball....
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Offline bpape

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Re: "Soundproof" Partition
« Reply #12 on: October 06, 2010, 06:37:27 AM »
I feel special Rich  :rofl:  Looks like an interesting project. 

If the middle is hollow, watch the 'thin plywood' thing or you can end up creating resonances right in the range you're trying to avoid.

Bryan
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Offline richidoo

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Re: "Soundproof" Partition
« Reply #13 on: October 06, 2010, 06:48:47 AM »
I would just bare with it, you are not going to be able to anything without making it look real oddball....

Werd, are you talking about my nose, or the paint?   :D

Bry, you are special!!  The innards are stuffed with 2" 703. Should I glue it to the skins?  The frames are 2" wide, so it matches the FG thickness. 
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline bpape

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Re: "Soundproof" Partition
« Reply #14 on: October 06, 2010, 07:58:05 AM »
Hmmm. Well, it's damped at least.  Just concerned about how much vibration and transmission you're going to get through it without a lot of mass.  Are both exposed sides going to be thin plywood or just the kitchen side?  Define thin  :-s
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