R19 fiberglass and need opinions on my situation

[tomlinmgt]

Ok, so some things are starting to come into focus now. Sounds like I need to balance the left and right walls by creating more reflection on the left wall (shelves) and more diffussion on the right wall. Keep in mind that I will be putting up panels at first reflection on both side walls so this means the CD shelf will be moved to the left (toward the water heater) a foot or two. Now, since the panel that will go up at first reflection on the right side wall will have the reflective wall surface behind it, I'm guessing I probably need to create a reflective surface behind the panel that will go up at first reflection on the left side wall (shelves). Correct?

For the corners...if the water heater is creating an obstruction to the corner how much of the soundwave is getting behind it?. There is much less resistance above it where there is nothing but some plumbing. Would I begin to get some effective absorption in that corner if I did a superchunk trap out of either 2" thick 3lb. density 703 or 2" thick 3 lb. density Roxul mineral wool cut into 2' base triangles starting at the top of the water heater and going up to the ceiling?

And in the oppostive corner if I put up a relective surface in front of the shelf that's butted up against the wall I would have a corner that is created by two solid reflective surfaces rather than one solid surface (the wall behind the speakers) and a shelf with knick knacks on it. Then I could do another superchunk type of trap in the left corner I created. If that seems like a move in the right direction, should I do a floor to ceiling superchunk trap in the left corner or do I try to simulate the reflection/diffraction I'm getting from the water heater by putting a solid object of similar dimension there? Which leads me to ask if the superchunk concept is plausible then do I need to put something around or in front of the water heater to cut down its reflection/diffraction? Maybe a corner panel that stadles the two walls but only comes up as high as the water heater?

 

[dka56]

This is what I would do if I had to use the garage area you have shown to be my dedicated listening area.

First is I would lay down some carpet like a berber..nothing too fancy and you could easily get a large remnant from a flooring company and some pad.

I would build a wall behind the components of 2x4's (16"OC) and fill it with either rockwool or your R19. Back it up with either some MLV or two layers of drywall...5/8 preferred.

Not sure how you could make a left wall but again if you're going to use this area for a long time then another 2x4 wall is the way to go. This option however makes for a tedious teardown if you end up parking cars or moving. You could hang some open-cell panels and face them with the burlap sacks, same for the right.

You sound like you are on track with your project, you have the ideal shape at least for a nice listening area but don't make it too complicated. I don't think the concrete floor is helping much so a carpet should help alot.

Don't cover or block the panel, i'm serious.....don't give your insurance company ANY reason to deny a claim if something went south. You may think i'm sounding like a nagging parent but i've heard too many stories. You leave, a fire starts somewhere, fire dept puts it out, notes the panel blocked and surely not to code...you're paying for either a slab or repairing on your own dime.

Build at least 3 walls, some bass traps in the corners...pull the speakers out from the back wall a foot or so and just keep adjusting till it sounds right.

 

[VolvoHeretic]

Ever been to a large lecture hall at college? They had giant chalk boards on wheels. You could build your wall, add something like 3 foot wide legs at each end (more like 4 feet), diagonaly braced to the panel and roll it out of the way when you need.

 

[dka56]

Ever been to a large lecture hall at college? They had giant chalk boards on wheels. You could build your wall, add something like 3 foot wide legs at each end (more like 4 feet), diagonaly braced to the panel and roll it out of the way when you need.

That's really a great idea.

Casters can be a little pricey for the good ones but would be your best option, so choose wisely...Harbor Freight can sometimes be a good friend. You could easily alter the size of your room to change acoustics this way and move them when space is a concern.

 

[tomlinmgt]

Yep, the wall on casters is a very good idea.

So that gets me a solid reflective surface on both sides and still allows access to the shelves with minimum hassle. Put up one of the 2.5' x 8' R19 panels I built at first refection on each side wall and that's a done deal.

Now, back to my other questions wrt superchunks in the corners and dealing with the water heater......any ideas/comments?

 

[dka56]

Have you considered moving one row of shelves on the left, over to the wall with the water heater?

Looks like you could compress the items on the shelves and possibly lose one stack. This way you could move everything to the left and have a 2nd wall on casters on the right.

 

[tomlinmgt]

Have you considered moving one row of shelves on the left, over to the wall with the water heater?

Looks like you could compress the items on the shelves and possibly lose one stack. This way you could move everything to the left and have a 2nd wall on casters on the right.

I won't be able to decommission one shelf. I have a bunch of drum gear that I'm going to need to store on the shelves after I make my arrangement a little more tidy and space efficient. I'm definitely gonna' need all three shelves.

I was thinking of making the wall that will cover the shelves be in two sections. One wall section being the roll away and it will cover the left and middle shelves and the other section being a semi-permanent wall that covers the shelves butted up against the wall. This way I create a corner that is somewhat permanent so that whatever bass trap I go with won't be disturbed when I need to roll the wall away to access the other two shelves.

Still hopin to get some input on the superchunks and water heater situation I presented in thread #21.

 

[VolvoHeretic]

That's really a great idea.

And they said smoking dope destroyed your memory and they also said I wouldn't ever have anything to contribute to society 35 years ago right before I dropped out.

 

[tomlinmgt]

And they said smoking dope destroyed your memory and they also said I wouldn't ever have anything to contribute to society 35 years ago right before I dropped out.

Go twist one up and sit back with some killer tunes as a reward for your worthwhile contribution.

You know, I found you just forgot the stuff that wasn't important.

 

[tomlinmgt]

Alright, now back to business guys. The weekend is fast approaching, I don't have the kids, and I've found good pricing on 2" 703 in 3 lb. density, 2" Roxul in 4 and 8 lb. density, and much to my delight 2" thick, 12" and 14" dia. 703 cylinders (which I'm thinking could be used like the ASC Tube Traps). The 703 is $7 for a 2'x4' panel, the Roxul 4 lb. is $5 and 8 lb. is $7 for a 2'x4' panel, and the 703 cylinders (2" wall thickness, 3 lb. density, 3' tall) are $12 for the 12" dia. and $16.50 for the 14".

So my decision now is type of corner traps. I like what I read about the superchunks but am really interested in the versatility and portability of the tube traps. This is the route I'd probably like to go IF the 703 cylinders have comparable performance to the superchunks. Here's the cost breakdown to treat the corner without the water heater....

703 superchunks......$42
Roxul 4 lb. " ........... $30
" 8 bl. " ................. $42
12" 703 tube trap.... $24 (6' tall)
14" " " ................. $33

For the corner with the water heater I'll have to do superchunks from the top of the water heater to the ceiling (this will maintain unobstructed access to the breaker panel) and not really sure what to do in front of the water heater. I mean, I'd like to balance that corner with the other corner so I guess I'll need absorption there. Perhaps a little partition of panels 4" thic that is only as high as the water heater but totally encapsulates it?


Keep the feedback comin'.

 

[VolvoHeretic]

I'm guessing that your water heater is about 21" in diameter? I wonder how much that 14" pipe insulation would give if you tried to wrap it around the water heater? It wouldn't have any air void behind the insulation though. How about cutting 12" insulation in half and arranging that around the water heater?:scratch2:

 

[tomlinmgt]

I'm guessing that your water heater is about 21" in diameter? I wonder how much that 14" pipe insulation would give if you tried to wrap it around the water heater? It wouldn't have any air void behind the insulation though. How about cutting 12" insulation in half and arranging that around the water heater?:scratch2:

Damn, man....that is friggin' brilliant. Admittedly, I'm not enough of an authority on acoustics to say definitively if that will yield the best results, but from what little knowledge I have acquired from gobbling this acoustics stuff up for the past few weeks I have to say your idea is the best I've heard yet. It creates airspace behind the absorption medium, it offers some measure of contour so that intrusion into the room is minimized, it's reasonably priced ($24....hell yeah!), it's aesthetically interesting....another worthwhile contribution to society from the drop out! Smoke up, man! :thmbsp:

Only thing I might add to that is increasing the wall thickness of the arcs to 4" by layering sections of 14" pipe insulation over the 12" sections. You think it's necessary? I mean, I'd prefer to not have to spend the extra money but if it's gonna' mean the difference between something that kinda works and something that really works then I certainly won't be belly achin' over another $33.

 

[VolvoHeretic]

Thanks for the compliment tomlinmgt, I know nothing about acoustics. I figure that rigid insulation won't form easily, so abondoned that idea, although you could sure double the 14" over the 12" if someone says that would help.

Edit; And by the way, I finally went back to school after 30 years, spent 60 hours per week doing homework, and graduated with a 3.89 gpa kicking my fellow teenage classmates butts getting straight A's except for two B's in English because my term papers were too long.

 

[tomlinmgt]

Thanks for the compliment tomlinmgt, I know nothing about acoustics. I figure that rigid insulation won't form easily, so abondoned that idea, although you could sure double the 14" over the 12" if someone says that would help.

Edit; And by the way, I finally went back to school after 30 years, spent 60 hours per week doing homework, and graduated with a 3.89 gpa kicking my fellow teenage classmates butts getting straight A's except for two B's in English because my term papers were too long.

Yeah, they say thickness is the key to killing the LF soundwaves.
And please, understand I wasn't takin' jabs at you for dropping out...though I'm figurin' you probably didn't take it that way.

At any rate, I really appreciate the ideas. I fancy myself as pretty resourceful and you gave me a couple of ringers that didn't occur to me. Thanks!

And I'm a car guy (road race '68 Camaro in my stable) so I'm diggin' the canyon carver look on the 1800 in your Avatar. I had an eccentric calculus professor in college with one of those and I dug it's killer lines every time I saw it....though it had more rust than good sheet metal!

Anybody care to comment on the 14" 703 tubes (pipe insulation) used as corner tube traps versus the superchunks?

 

[tomlinmgt]

Alright...just picked up 15 panels of 2" thick 3 lb. density 703 and later today will start cuttin' em up into triangles for my superchunk style corner broadband absorbers (bass traps). Might as well do it here at the shop since I have a spray booth to suck out all the floating fiberglass I'll generate. Off to Lowes after work to pick up a couple of plywood panels to wall off my shelves. Don't know how much things will improve, but I'm having a blast. If it actually does make a significant difference I'll be a bonafide acoustics junkie.

Now, I need to figure out where the six panels I have already constructed could be used. I have the two 2.5'x6' 7" thick compressed R13 panels and the four 2.5'x8' 6" thick non-compressed R19 panels. I need clouds on the ceiling, sidewall panels at first reflection, and I guess panels on the wall behind the speakers or up in the corner created by the wall behind the speakers and ceiling....or both.

Also, is there a minimum thickness for plywood for it to be reflective? The panels I'll be using for the faux wall will be portable and I'd like to keep them as light as possible. They will get painted as well.

 

[dka56]

Sound waves are accelerated through the plywood, in open air it's roughly 1100 ft/sec....in plywood it's about 13,000 ft/sec....so you surely don't slow it down. It's definately an in-depth science. I would use drywall sandwiching a layer of Roxul..and is prop cheaper than the plywood.

Are you trying to reflect the sound or absorb it to minimize reflections?

 

[VolvoHeretic]

3/4" plywood is pretty heavy and will still cup with the change in humidity without being reinforced. 1/2" is even worse. I would get 7/16 osb board if you aren't going to add 2x or 1x structure to it. It's a very stable dimensionaly product and is the cheapest you can find. Gypsum board will never last if you are going to attach and detach it from the shelving.

 

[tomlinmgt]

Sound waves are accelerated through the plywood, in open air it's roughly 1100 ft/sec....in plywood it's about 13,000 ft/sec....so you surely don't slow it down. It's definately an in-depth science. I would use drywall sandwiching a layer of Roxul..and is prop cheaper than the plywood.

Are you trying to reflect the sound or absorb it to minimize reflections?

Well, the wall opposite the faux wall I'm creating is typical framed studs on 16' centers with sheetrock. I'd like the faux wall to be similarly reflective so I have balance. As I said, there will be absorption panels at first reflection on each of these walls, and a cd shelf on the right wall for diffusion....and I'll put something up on the faux wall for diffusion as well.

 

[tomlinmgt]

3/4" plywood is pretty heavy and will still cup with the change in humidity without being reinforced. 1/2" is even worse. I would get 7/16 osb board if you aren't going to add 2x or 1x structure to it. It's a very stable dimensionaly product and is the cheapest you can find. Gypsum board will never last if you are going to attach and detach it from the shelving.

I was hoping to do 1/4" plywood with a 1x2 frame to keep it lightweight . But I have concerns about the 1/4" not being dense enough to reflect. What do you think?

 

[VolvoHeretic]

Well, and again, I know nothing about accustics, but 1/4" plywood glued over 1/2" fiberboard (Buffalo Board) wall sheathing, nailed and glued together with some PL400 (edit; actually, spreading latex linoleum floor glue with a notched trowel would really bond the two together) would be as light as you can get and still be well dampened, and act just like drywall, or close enough.

I used to build plenty of curved walls back in the day when I was a carpenter. If a 90 degree corner is creating the standing waves, wouldn't eliminating the corner also eliminate the standing wave?(edit; I mean a convec or concave curved wall in the corner, I don't know which.)