Questions about John's diy absorbers

Ptownkid · Post by **Ptownkid** » Thu Jul 15, 2004 1:01 pm

What type of cloth is used?

What are the back (1/4") panels made of on each design?

What are the slats made of?

Why is there a rear absorber at the front of the room diagram, and is it important?

All of the drawings I've seen here show 30 degree angles in the front corners of the control room, why are the corner traps almost 45?

Thanks, I'm a total noob...

giles117 · Post by **giles117** » Thu Jul 15, 2004 2:35 pm

If you read the caption in it's entirety

The rear of the unit is covered by plywood to create a sealed unit.

Slats are 1x2,1x3,1x4 So pick your wood, pine, oak, mahogany, cherry, etc.... 1" thick wood by the various widths.

(rear absorber on front wall) To capture front reflections off of the rear of your montiors and any remaining sound bounce off of your rear and side walls.

Where are you getting a 30 degree dimension from please post of link the photo so a correct response can be given.

Cloth can be any type you choose. i used a broadcloath , some use muslin.

Bryan Giles

Ptownkid · Post by **Ptownkid** » Thu Jul 15, 2004 11:54 pm

Thanks for your reply.

I completely missed where it said plywood, that's what i get for reading half asleep.

Here's a link to a studio plan from this site. Every one i have seen here shows the same type angles in the front corners of the control room. That is what prompted my question about the corner units

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=1914

Also, I checked the owens/Corning site, and it seems as if they only sell rigid insulation up to 2" thick. Does anyone know if this is the right stuff?

http://www.owenscorning.com/around/insu ... amular.asp

Thanks very much

Bryan Mills

AndrewMc · Post by **AndrewMc** » Fri Jul 16, 2004 12:12 am

The link you have posted is NOT the right stuff to use. You need 703 fiberboard - this is dense glass fibers, the link you posted is for a kind of polystyrene insulation product.

703 is yellow and you can get it 1, 2, 3 inches thick.

If you go to Home Depot they will probably be able to special order it for you.

giles117 · Post by **giles117** » Fri Jul 16, 2004 12:33 am

The 30 Degree angle you speak of is your speaker soffit.

The purpose of the angle is to give you a nice stereo image (feild) to listen/mix in.

I you look around, there is a lot of older information detailing this out, showing the various mix posisitions, and some evolutionary information as well.

Bryan Giles

Ptownkid · Post by **Ptownkid** » Fri Jul 16, 2004 12:59 am

Thanks Andrew, i'll go look into that

Bryan, so basically I should disregard that idea and make the corner traps as planned and sit my monitors on my desk to form the hypothetical speaker to ears triangle?

Thank you both very much for your help, I appreciate it immensly. This is a very confusing endeavour.

Cheers

Bryan Mills

Hashbrown · Post by **Hashbrown** » Fri Jul 16, 2004 5:00 am

and sit my monitors on my desk to form the hypothetical speaker to ears triangle

to form this triangle the speakers themselves should still be at 30 degree angles. That's why the soffits are at 30 degrees, it forms an equilateral triangle.

Ptownkid · Post by **Ptownkid** » Sat Jul 17, 2004 1:27 am

Couple more questions

On the corner traps, the front trim pieces aren't necessary are they? I'm having a hard time trying to fuigure out how to cut the top and bottom triangle pieces when the trim pieces jut out.

How do i fasten the insulation in the corner traps?

For the side and rear absorbers, it says 7 foot by 4 foot, yet it says height determined by the ceiling height. How wide are they supposed to be?

Thanks again

Bryan Mills

giles117 · Post by **giles117** » Sat Jul 17, 2004 1:52 am

The width I belive is 4 feet.

thanks hash.

For your purposes Bryan (good name there Guy and you use the correct spelling no less. Glad to know great people are in the world

LOL)

Anwayz.... Like you said build your bass traps and place your monitors on stands. However what you lose is the wonderful tightness the soffit mounted montors give to your bass and the imaging you get.

I am a die hard soffit guy cuz what i have heard in major studios with nearfields on the monitor bridge and in my studio with nearfields in soffits is so wonderfully different. I refuse to go to the BIG studios (unless they write a big enuff check. LOL. Or the room is wyhiwyg) what you hear is what you get.

Of course I am in Detroit and we only have 2 major studios that gives you that. the 3rd.. was a nice place till they replaced the soffited speakers with these Genelecs. They Never did get it tuned right.

BRING MOTOWN BACK. well maybe not Motown, but our Wonderfully gifted music scene!!!!!!

Bryan Giles

Ptownkid · Post by **Ptownkid** » Sat Jul 17, 2004 3:01 am

Well, could i build the corner traps in the front of the room with cavities for the monitors and aim them accordingly? I realise full well that if I am to do this, I'll have to make the cavities sealed inside so that the trap is still pretty much airtight. Would this work?

Also, I still need to know how to attach the insulation inside the trap, and are the front slats glued on or screwed?

Lastly, I have a bit of a problem, we can't get 700 series OC fibreboard insulation in canada, what now?

Is this similar?

http://www.roxul.com/sw18178.asp

here's the specs

http://www.roxul.com/graphics/rx-na/can ... /rxl80.pdf

Thanks tons

Bryan Mills

PS, the more i looked, i found a couple more products like the above

The choices are rxlt board, rhf industrial and rht industrial, why couldn't they just have one choice? I really don't know which ones are ok and or best.

Ptownkid · Post by **Ptownkid** » Sat Jul 17, 2004 3:53 am

Well, i just found out that the rxlt only come with a minumum order of 100 sheets, about 4 times what i need so it's down to these

I put all the numbers in the next post...

http://www.roxul.com/graphics/rx-na/can ... hnical.pdf

http://www.roxul.com/graphics/rx-na/can ... hnical.pdf

http://www.roxul.com/graphics/rx-na/can ... t_info.pdf

http://rw-misc.inforce.dk/graphics/rx-n ... t_info.pdf

Ptownkid · Post by **Ptownkid** » Sat Jul 17, 2004 4:08 am

astm c 423 co-efficients

product
125Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz NRC
rht 80
2" 0.39 0.84 1.08 1.01 1.02 1.01 1.1
3" 0.68 0.92 1.08 1.03 1.03 1.03 1.1

rht 60
2" 0.26 0.71 1.14 1.09 1.04 1.03 1
3" 0.65 0.94 1.13 1.07 1.06 1.04 1.1

rhf 60
2" 0.26 0.71 1.14 1.09 1.04 1.03 1
3" 0.65 0.94 1.13 1.07 1.06 1.04 1.1

rhf 80
2" 0.39 0.84 1.08 1.01 1.02 1.01 1
3" 0.68 0.92 1.08 1.03 1.03 1.03 1.1

oc 703
2" 0.17 0.86 1.14 1.07 1.02 0.98 1

As you can see, the numbers for the RHT and RHF are the same, I was told that one uses more binder and is stiffer, any thoughts?

Ptownkid · Post by **Ptownkid** » Sat Jul 17, 2004 4:27 am

Allright, i just finished reading this thread

http://www.johnlsayers.com/phpBB2/viewt ... 12&start=0

It says that 8lb is too dense, so, should i be using this?

http://www.roxul.com/graphics/rx-na/can ... t_info.pdf

I know I've tossed a lot up here today, but I appreciate everyone's help tons, I'd be lost without it. Not to mention poor from wasting money.

Cheers

giles117 · Post by **giles117** » Sat Jul 17, 2004 8:07 am

Where are you located, My Local supplier sells me a bundle at a time if needed, perhaps we can find you a supplier. And make sure you post this info over in the Building Products forum.

Bryan giles

Ptownkid · Post by **Ptownkid** » Sat Jul 17, 2004 8:25 am

I'm in ontario canada, and owens corning says they do not sell it in canada.

Besides, i found out i have a connection to go to Roxul directly so is the above material right?