# Need detailed plans for



## shep (Nov 22, 2009)

building a 8' x 24" x 17" x 17" freestanding corner bass trap. I have searched til I'm blue online. I need it to include what/how much materials ( as photos alone don't tell me much) I need for each one I make. I plan to build 4 of them. Thanks very much! - Shep


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## bpape (Sep 14, 2006)

6 pcs of 2'x4'x2" OC703 will build one of those. Cut each piece into 8 triangles. 16" of height per sheet.

Bryan


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## shep (Nov 22, 2009)

Thanks for the reply. Can you point me to a set of plans I can download to do this?


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## bpape (Sep 14, 2006)

Bryan


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## shep (Nov 22, 2009)

I appreciate that, but I'd like it to be freestanding - I don't want to attach to a wall if at all possible. Some kind of lightweight frame...


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## bpape (Sep 14, 2006)

Don't have any plans for that - sorry. I've seen some pics of stick frames people have done. Don't remember where they are though. 8' free standing will be a bit tough and a bit unstable if not attached to the wall somehow.

Bryan


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## shep (Nov 22, 2009)

I'll need to find a minimal, hidden way to attach it.


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## bpape (Sep 14, 2006)

Industrial Velcro along the hidden edges and the wall? 

Bryan


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## shep (Nov 22, 2009)

Do I want it flush to the wall? I'd heard a few inches off the wall - but, I know nothing (in my best Sgt. Schultz). Good idea if I put them flush. Thanks much for all your help, Bryan.


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## bpape (Sep 14, 2006)

With a chunk style absorber, flush is good. It's only when you have a flat panel and have it not straddling the corner where some additional spacing will help extend the bass response.

Bryan


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## shep (Nov 22, 2009)

I read a comment fom Ethan this morning that FRK should be used with the foil facing out for corner traps. I see it is more than twice as expensive (@ ready acoustics) than the $59 for 6- 2" thick ATS rigid fiberglass sheets. Is this a drastic improvement, or only marginal?


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## bpape (Sep 14, 2006)

FSK will simply limit the amount of high frequency absorption. In the front of the room, you don't want to do that. With a chunk style design, it's almost impossible to bond the FSK as you'd be trying to do it on the edges while the pre-faced is just that, on the faces and would never be seen.

Ethan is talking about when you'd use a pc of 4" straddling a corner rather than a chunk. The chunk will vastly outperform the 4" FSK straddling a corner.


Save your money and buy the unfaced.

Bryan


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## shep (Nov 22, 2009)

I can't thank you enough for the valuable info, Bryan.


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## bpape (Sep 14, 2006)

No problem. Make sure to post some pics when you're done.

Be careful with the ATS '703 equivalent'. There are such things out there certainly. However, when they say it's 'softer and compresses easier', that tells me it's not the same density. Just FYI.

By the way, where in Illinois are you?

Bryan


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## shep (Nov 22, 2009)

Springfield


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## shep (Nov 22, 2009)

I've got a contractor friend who can order from the supply stores for me, so that should save shipping.

I was looking at corner bead like this to make the trap frames:

http://www.lowes.com/pd_11822-325-1...pl_Drywall+Corner+Bead_4294858285_4294937087_

I changed my thinking to 4' high, as a friend suggested I'd be able to easily move them around in the room to help w/ isolation issues when using a mic. they'd likely stack well, thus freestanding if placed all the way into the corners. Seem valid to you guys?


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## bpape (Sep 14, 2006)

I've seen them mad that way before and they seemed to be OK. The biggest thing is just getting the sharp edges tamed somehow so you can cloth cover them without tearing the fabric.

Bryan


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## shep (Nov 22, 2009)

My wife can't figure out how to attach the fabric to the metal without wood to staple to - nor can I. Wouldn't the staples show anyway?

I saw pics ( here: http://gallery.avsforum.com/showphoto.php/photo/21647 )where a guy used a dowel on each corner and attached it in a triangle base of sorts. But no info on making it. I can't see how the pieces are held inside it - the front sticks out past the dowels.

There's yet another obstacle in getting these all the way into the corner. When we moved in, wife wanted crown molding in this room, as it is a dining room - so, I won't be able to get the frames all the way into the corner. This is waaay more of a pain than folks make it out to be - and more than I ever imagined. Frustrated by how many hours I've spent developing a plan, and have nothing to show for it. Please advise and thanks - John


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## bpape (Sep 14, 2006)

Just make them a little shorter to avoid the crown - you'll be fine. 

If you want, you can use a small wood frame inside the metal frame and tack through the holes. 

Bryan


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## shep (Nov 22, 2009)

Would I put it only on the back side so staples were only visible from the back - or will I need it on all sides? It could be fun hitting the holes when I can't see them for the fabric. I'm looking for some find of foam pad/or similar material for each side to keep the metal from cutting the fabric. Maybe just duct tape it.


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## bpape (Sep 14, 2006)

Pretty much. Seam at both rear corners and make up a 'grille' that you can velro on to it.

Bryan


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## shep (Nov 22, 2009)

I bought 4 bundles of 9 sheets of 2" Johns Manville 814 fom Chicago SPI Insulation for $288. Shipping was $150!!!!!!!!! No place in Spfld I could even order it from - why? No clue why, I even had a local contractor call for me about it. 

I ended up making the wood/dowel pattern Tweakophyte posted over at AVS forum.. Built the frames,cut the insulation, then cut an inch off each corner so the pieces fit all the way to the back, greatly reducing the gap the 3/4 dowels create. Bought 8 twin flatsheets at Walmart for $4 each to cover. 

This is the hard part. I bought double stick tape to put on the dowels to snug up the material. No matter what I try, every little inconsistency shows. No clue how to get these tight looking and smooth. If I cut down the insulation more, I'm concerned it wil move around and push on the material, leaving me w/ a less than good result. I looked at Tweakophytes' pics here:

http://gallery.avsforum.com/showphoto.php/photo/21596/ppuser/3833

and have no idea how he could get speaker cover to be so smooth around the front edges when the insulation sticks out past the dowels. Should I cut all these pieces back so they are inside the dowels? The more I cut the less absorbancy I get....

BTW - IMO this is a much harder project than most claim it is. I have worked w/ power tools plenty in my work, so I am not a noob. It took me almost 2 days to get to the covering part of the project. And I can see covering taking 2 days doing it by myself. And that doesn't speak of the 6 - 2x4 wall diffusors I've yet to start. Frustrated to say the least... Please advise - Shep


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## bpape (Sep 14, 2006)

What are you doing with dowels? Got pics?

Bryan


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## shep (Nov 22, 2009)

See the link above - I made the frames like that.


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## bpape (Sep 14, 2006)

Gotcha. Yes, the fiberglass triangles will have to be smaller than the inner size of the dowel triangle. 

Probably easier to make new frames with the inside of the dowels slightly larger than the 17x17x24" triangles rather than cutting all of them. 

Even with 3/4" diameter, I suspect there may also be some bowing when you try to stretch the cloth tight.

Bryan


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## shep (Nov 22, 2009)

OK - I uploaded some pics.


http://dl.dropbox.com/u/1870114/Frames.jpg

http://dl.dropbox.com/u/1870114/Insulation loaded into frame.jpg

http://dl.dropbox.com/u/1870114/Crappylookingproduct.jpg


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## shep (Nov 22, 2009)

There is NO WAY I can afford to buy new wood, so I guess I have to recut evey one of these pieces - what, 120ish? You can't cut 2x2 sheets of wood to be bigger than the insulation triangles, can you?


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## bpape (Sep 14, 2006)

Sure. The triangles are only 17x17x24, right? If so, you can split a 2x2 sheet of plywood into 2 triangles that are 24x24x34 though you don't need them that big. I'd just go like 19x19 and cut a diagonal from there.

Bryan


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## shep (Nov 22, 2009)

That would have used up much more plywood, so i decided to bite the bullet.

I took a trap out to the garage, shaved a triangle til it fit well, then recut the rest and tried covering it again. Much hassle, much preferred result. Sure wish i had known _exactly_ what size to make these in the 1st place, but at least I can see that they are gonna look great. Once I'm all done, I'll take a few more pics and post a file with exactly every move/ measurement I used. Thanks again for the help, Bryan.


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## bpape (Sep 14, 2006)

Nicely done. Very clean look you ended up with.

Bryan


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## shep (Nov 22, 2009)

I finally finished the corner traps. Pretty happy with the end result. I started on the wall units. I'm using 1"x4" wood, put 2-2x4 sheets into it. It's overfull. May make covering difficult. Advice?

Also, i've looked at alot of pics, but don't see clear details of how to mount these to walls/ceiling. Please advise. Thanks much, Shep


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## shep (Nov 22, 2009)

Anyone? Wanting to finish this weekend - Thanks, Shep


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## Prof. (Oct 20, 2006)

The easiest way to mount them to the walls is to use Velcro..
For the ceiling mount panels, you'll need to use angle brackets..


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## shep (Nov 22, 2009)

Thanks much for the reply Prof. Shack Moderator! If I use a 4" absorber - am I supposed to keep it 4" off the wall? I can't see how velcro will provide the gap.


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## Prof. (Oct 20, 2006)

If you're planning to space them off the wall then they only need to be about 2" away from the wall.
For that type of mounting, you'll need to use angle brackets to space them off..


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## shep (Nov 22, 2009)

I have 7 - 2'x4'x4" wall absorbers built and mounting hardware ready. I'm unsure what height from the ceiling to mount the 6 that will go on the side, front, and rear walls. #7 is the ceiling cloud.

In my 12x10 room, am I better off grouping the side wall absorbers at the mix position, or equally space the rear set between the mix position set and rear bass trap (distance between is 6')? Please see pics of side wall. 

From pics I've seen, the 1st reflection absorbers are placed between the speaker and listening position - correct? Thanks very much - Shep


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## bpape (Sep 14, 2006)

I would do 2 on the ceiling over the mix position, 2 on each side wall for reflections (yes they will fall between the speakers and you), and the other 3 scattered about the space in the areas behind you. Potentially one of those might be used horizontally on the front wall between the monitors.

As for height, usually we start the reflection panels 18" to 2' off the floor.

Bryan


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## shep (Nov 22, 2009)

Thanks Bryan. I have some considerations about your suggestions: please see pics. If you're wondering - the front french door has 2" styrofoam covered with fabric to reduce sound leakage into the house. I put one in the rear door when I close the door once inside.

Should clouds be side by side or front to back?

Big French door on front wall - should I hang 1 vertically here?

Small french door here, room for 2. So, is this a best scenario based on what you see?

2 on ceiling 
2 on side walls
2 on back wall
1 on front wall


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## bpape (Sep 14, 2006)

That would be fine if you want to do 2 on the rear wall and only 2 on the side walls instead of 2 on EACH side wall.

As for the cloud, doesn't matter. You're shooting for a 4'x4' cloud.

Bryan


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## shep (Nov 22, 2009)

Which is a higher priority - side or rear? Thing is I only have 7. Using 2 on 2 sides is 4, add 2 up top is 6, leaving 1 for the front OR back, not both. Thanks very much - you are one helpful person, sir.


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## bpape (Sep 14, 2006)

It's just different. 2 on each side and none on the rear gives you the option for a more live space in the rear if you ever want it. That said, if you're getting bass issues coming off the rear wall, you may have to do the rear wall instead. No way to know for sure until you measure it.

Bryan


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## shep (Nov 22, 2009)

This has cost me enough cash already (according to the wife) - so buying db meters and omni mics is out of the picture for me now. Think I'm gonna do 2 on the back wall and hope for a good result... Thanks!


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## shep (Nov 22, 2009)

Ok, I lied. Put one on back wall, one between speakers. Two for a cloud - not enough room to do a 4x4 square and center it because of light fixture. I have one more made, and enough insulation left to make 1 more when I get the 1x4s. I'll put them on the side walls. Here's a couple pics. Pretty happy w/ results. :sweat:

I still have a slap in the room. I hope the additional pair will get rid of it. If not, what is the way to make it die? Thanks very much - Shep


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## bpape (Sep 14, 2006)

It's likely up high around the perimeter of the room. You have enough broadband in there that pretty much anything will work. 

Also, why 1 front and 1 back? I'd do 2 in back.

Bryan


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## shep (Nov 22, 2009)

> Also, why 1 front and 1 back? I'd do 2 in back.


I heard that the front reflections will get to my ears faster than the back, and would be louder from proximity. Also, I've read hear that doing the front wall is more important than the back wall. Also, 2 won't fit side by side on the back wall. 11.5 x 9.5 - tiny space.

Should I put the 2 panels I have left horizontally up high then? Maybe 45 degree angle off the ceiling on each side would kill it? It would save me some much needed space in the back of the room as well. If not, what kind of anything would look good and be effective?
Thanks Bryan - Shep


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## bpape (Sep 14, 2006)

What you're looking to do is kill behind your seated ear position as much surface area as possible and as thick as possible. Maybe a couple horizontal panels that are 2'x3'? 

Bryan


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## shep (Nov 22, 2009)

Thank God - I'M DONE!!! The last 2 panels up high horizontally got the bad slap out. We'll see if anything shows up the 1st time I put a mic up. I can bet at this point that I'll hear a difference in my mixes. Since I have no before and after data to support claims of improvement, I'll post a 'before and after' example of a tune I'm working on currently that I think will show how much more accurate the environment has become. 

Thanks very much again Bryan - you have been a great resource. Hope I haven't caused you too much stress along the way.:wits-end: 

Gonna go in right now and listen to the results of the efforts. Take care - Shep


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## bpape (Sep 14, 2006)

No problem. Glad to help. Enjoy your new room setup.

Bryan


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