different densities for different panels..?

[jpgetty2win]

hi guys

been reading up alot over the past couple of weeks. wow, theres alot to get through.. lol
now i think ive got my stuff together but just wanted a couple of things clarified..



im going to be making acoustic panels for reflection control with RS45.. 2" thick. 3" off the walls.

my design for the panels is this:

http://bigfish.fileave.com/acoustic%20panels.JPG

would these be ok? (no backing board and no wood on the sides.. just a thin rim on the back, to attach the spacers and attach the hanging system)



for the corner bass traps i need to know what densitiy is best for superchunks..? the corner triangles for the superchunks will be 16"x16"x32" (approx) set 3" off the wall(s).
should i just make them out of RS45 again or someting denser RS100..? OR should it be LESS than RS45 instead of higher density??



for the ceiling/wall traps (straddling the wall ceiling "dicorner") i was going to make them 2", but should they be 45 or more/less?
also for the cloud?? thinking about doing the cloud as a 4" but what density? higher or lower than 45?


please help clarify these last few queries i have. it would be a massive help!

THANK YOU

[Glenn Kuras]

would these be ok?

Looks fine to me.

for the corner bass traps i need to know what densitiy is best for superchunks..? the corner triangles for the superchunks will be 16"x16"x32" (approx) set 3" off the wall(s).
should i just make them out of RS45 again or someting denser RS100..? OR should it be LESS than RS45 instead of higher density??

RS45 is fine and you don't need to space it from the wall.

for the ceiling/wall traps (straddling the wall ceiling "dicorner") i was going to make them 2", but should they be 45 or more/less?

45 degrees yes, but you want them no less then 4" thick

[jpgetty2win]

hi glenn! was hoping id get a reply off of you!! thank you!!

regarding my design, do you think i need to fabric cover the back of the panels for safety too?

thanks for the tip about not having to have the corner superchunks set away from the wall! so RS45 would be ok, i can get other densities and investigated getting them for the corner traps cos i read so many people saying you need other densities for the corners (people using 703 and 705 etc in their rooms)


so the wall ceiling traps should be 4" min as well as the cloud, thank you! regarding the "45", i meant RS45, sorry, should have written the full name


so youre saying RS45 should be used for all parts, the panel reflectors, corner superchunks, cloud and celing/wall straddler??


been readin lots of your posts and so await you reply with great anticipation!

[DanDan]

The performance of various densities does not vary much until dimensions change a lot. Very often the choice has to be due to practical matters, e.g. local availability. Generally 703 is considered as almost the perfect balance of properties.
The equivalent would be RS60, or RW3. The Rock products tend to be much floppier than the glass. The Cloud may sag. I reckon RS100 would be a good choice for panels up to 4 inches. Thicker than that and you need to go for lower densities. 45 or even less will be fine for SuperChunks. Great design here Corner Traps finally finished! - Home Theater Forum and Systems - HomeTheaterShack.com
I recommend a layer of FRK on the back of all panels, facing away from the listener. This gives a little help with LF modal control.
DD

[jpgetty2win]

ok ok ok starting to get things together in my head, thank you! and i hope youre getting some nice weather over on the green isle unlike here in london!

so...
you think i should make my 2" panels out of RS100, my superchunks and 4" ceiling/wall straddlers out of RS45.
hmmm now the cloud... gonna be 4" so i spose... RS60..? (softer than RS100 but not too soft that itll sag)

re FRK, on the back of the panels? i read ethan say they should always go on the front

[DanDan]

Weather's not bad at all. We're having a good friday.....
I haven't much experience of RS60. RS100 is like 705.
I reckon RS100 everywhere except the SuperChunks.
Light Fibreglass can be easier to use in chunks as it is relatively stiffer.
See Isover Duct Slabs.
FRK on the front of panels will enhance the LF absorption. It will also bounce some HF back into the room. This could be OK for corner straddlers, but personally I don't like that HF bounce. It's a taste, tone thing, these things do have a 'sound'. I would always put the FRK to the back. The LF effect is not as strong but it is still very worthwhile.
DD

[jpgetty2win]

hmm ok..

ive read you can use pretty much any thin paper as a FRK, but how do you attach it? (serious question) would putting a layer of glue over the rocksilk not create a "barrier" bouncing the frequencies back, not allowing them to penetrate (oooo er!) the panel?

[PaulP]

Originally Posted by jpgetty2win

would putting a layer of glue over the rocksilk not create a "barrier" bouncing the frequencies back, not allowing them to penetrate (oooo er!) the panel?

Spray glue would be best as it is thin and will remain flexible. You definitely
will be preventing the air from penetrating into the insulation so you'll now
have a membrane absorber. I presume that only frequencies/pressures that
are strong enough to move the membrane will be absorbed. If so, then the
stiffness of the insulation will play a role as well.

Paul P

[jpgetty2win]

Originally Posted by PaulP

Spray glue would be best as it is thin and will remain flexible. You definitely
will be preventing the air from penetrating into the insulation so you'll now
have a membrane absorber. I presume that only frequencies/pressures that
are strong enough to move the membrane will be absorbed. If so, then the
stiffness of the insulation will play a role as well.

Paul P

getting complicated again

[DanDan]

I would buy it with FRK attached. This is tested and proven. Rigid fiberglass density tests
If you are applying a membrane DIY, Spraytac seems to be the one. It creates a 'net' rather than a film layer. Remember that I recommend the FRK face away. Thus HF and MF will be absorbed in the 4 inch layer. LFM and LF will pass through, vibrate the membrane/panel, and get somewhat absorbed.
DD

[jpgetty2win]

Originally Posted by DanDan

I would buy it with FRK attached. This is tested and proven. Rigid fiberglass density tests
If you are applying a membrane DIY, Spraytac seems to be the one. It creates a 'net' rather than a film layer. Remember that I recommend the FRK face away. Thus HF and MF will be absorbed in the 4 inch layer. LFM and LF will pass through, vibrate the membrane/panel, and get somewhat absorbed.
DD

can you get rocksilk with frk though? what insultaion would you recommend if not rocksilk. looked for the Isover Duct Slabs, if i were able to get some of that what density equivalant should i look for for the panels, (the RS100 equivalant)

thank you for all the advice. its been a massive help.

[DanDan]

A search will show that availability of the 'right' insulation products is a widespread problem. That is because insulation is mostly used for thermal purposes at lower densities. I don't know what is available locally to you. The Isover Duct Batts are 48KG. The ones I got had FRK on. I found an insulation supplier who has all of the above, sporadically. You have to take what's there when you turn up. They actually cut Rockwool and glue on FRK. They sell Sprayfix glue and FRK on rolls! The sell to the industrial HVAC market, they are not a builders supplier. This is a small town so you may be able to find such a source.
Note that FRK is not specific. It is just a damp proof membrane, under 1 mil I guess. A plastic or even paper sheet should be fine.
DD

[jpgetty2win]

Originally Posted by DanDan

A search will show that availability of the 'right' insulation products is a widespread problem. That is because insulation is mostly used for thermal purposes at lower densities. I don't know what is available locally to you. The Isover Duct Batts are 48KG. The ones I got had FRK on. I found an insulation supplier who has all of the above, sporadically. You have to take what's there when you turn up. They actually cut Rockwool and glue on FRK. They sell Sprayfix glue and FRK on rolls! The sell to the industrial HVAC market, they are not a builders supplier. This is a small town so you may be able to find such a source.
Note that FRK is not specific. It is just a damp proof membrane, under 1 mil I guess. A plastic or even paper sheet should be fine.
DD

cool, im gonna go to B&Q now and have a look at what theyve got available (the FRK's i could use and adhesive sprays) a quick search showed on their site that they dont have spraytak (cant find any surppliers at all tbh). so ill see what alternatives they have. you say sprayfix is a possible alternative to spraytak?

[DanDan]

I have a can of Sprayfix here. No manufacturers name! Chinese I would imagine. SprayTac may be a 3M product.
Unfortunately I don't think B and Q and the likes will be any use.
You need to find an industrial outfit. Someone involved in HVAC, factories, ducting, silencing fans and other machines. OR try StudioSpares or Soundproofing Acoustic Sound Insulation Sound Proofing Noise Consultants - Custom Audio Designs Ltd Hampshire

DD

[Kertbert]

I'm in the same boat. I've found a great price for a 6 pcf rockboard. I'd like to have FRK facing out from my corner traps. The problem is, the only way for me to get panels with FRK (or FSK assuming same thing?), is to buy a few more expensive 3 pcf fibreglass panels. If all panels are 2" and I want a 4" unit FRK fronted unit, is it a problem to put the rockboard behind the fiberglass or should I spend more money and keep all 4" consistent (3pcf fiberglass)?

[DanDan]

Availability is THE problem facing us all. Rest assured though, it would be difficult to make a wrong choice here. It pretty much all works. The goal posts are very wide. I would put the rockboard behind the FSK glass with no qualms whatsoever. The extra density of the rock will be better than the lighter fibreglass.
DD

[jpgetty2win]

right.. the guys im getting the rocksilk off also sell this stuff:

EVERBUILD CONTACT SPRAY ADHESIVE
MONARFLOOR ACOUSTIC ADHESIVE CAN

you heard of either of them? useable?

[DanDan]

Dunno. Sprayfix and this Shop 3M: 3M Polystyrene Foam Insulation 78 Spray Adhesive
seem to be very suited for purpose.
Here's another High Grab High Temperature pressure sensitive web spray contact adhesive
Note the words 'web' and 'lace'. The can throws out a very light sort of spiders web of extremely sticky fast drying stuff.
DD

[jpgetty2win]

Originally Posted by DanDan

Dunno. Sprayfix and this Shop 3M: 3M Polystyrene Foam Insulation 78 Spray Adhesive
seem to be very suited for purpose.
Here's another High Grab High Temperature pressure sensitive web spray contact adhesive
Note the words 'web' and 'lace'. The can throws out a very light sort of spiders web of extremely sticky fast drying stuff.
DD

what about the "77"?

Shop 3M: 3M Super 77 Spray Adhesive

is this the paper i need?
750mm x 10m of STRONG Brown 70gsm Kraft Wrapping Paper on eBay (end time 04-Apr-10 09:33:15 BST)

[DanDan]

Glue looks good to me. Paper seems a bit light. Plastic sheet would be fine. Anything between 0.5 and 1mm. Garden centre? Paint spill sheet?
DD

[jpgetty2win]

Originally Posted by DanDan

Glue looks good to me. Paper seems a bit light. Plastic sheet would be fine. Anything between 0.5 and 1mm. Garden centre? Paint spill sheet?
DD

cool, ill have a look round my good old mate "B&Q"'s tomoz

had another look at the spray... dont say web or lace... think it might just be a spray

[PaulP]

Originally Posted by DanDan

Paper seems a bit light. Plastic sheet would be fine. Anything between 0.5 and 1mm.

(I might as well keep going in the direction I've adopted of late...)

Dan, with much respect from my end as well, what are you basing this
recommendation on ? Looks pretty thick to me.

Paul P