Owens Corning 703 vs. Roxul Safe 'n' Sound?

They are probably very similar. The Owens 703 -might- absorb slightly more sound because it is a little bit more dense (Owens 703 is 3lb, Roxul Safe-n-Sound is 2.5lb), but that is such a small difference.

https://www.atsacoustics.com/page--Selecting-the-Right-Acoustic-Material--ac.html

This page will help you decide between different types of acoustic materials.  Be very conservative when putting in acoustic panels.  Placement is very critical and one panel could suck too much liveliness out of the room.  Placement is critical.  Experiment with different placements.

I just recently experimented with diffusion panels on the side walls. They did not work out at all. I was using the 23" x 23" QRD diffusors (the ones from ATS Acoustics). It took some critical listening, but what happens with the diffusors on the side walls is that they will emphasize/boost some frequencies and then subdue/cancel other frequencies. I believe when the sound waves are bouncing around in the slots, it creates enough of a delay that it will cancel out the waveforms of some of the frequencies by the time it reaches your ears. Turning the diffusor upside-down so that the deeper slots or closer or farther from you will totally affect the sound as well. I could not get the diffusors to work on the side walls properly whatever I tried. Since I had to put them somewhere, I put them on the back wall. They seemed to work okay horizontally, because vertically they still cancelled out some frequencies. I would be very careful with using the diffusors. Always test out locations first and listen CAREFULLY before permanently mounting them.

Absorption is good -- up to a point. I have found that just adding a couple too many panels could throw the balance of the room off so that it is absorbing too much sound. What happens is that it starts to suck out too much upper mids/highs and you lose the excitement of the room. It’s a fine line, but once you’ve crossed it, the room becomes dull.

I found the best placement in my room is to have a 24" x 48" x 2" panel behind each speaker (they are in the front corners). Then a 24" x 48" x 2" panel in each of the back corners of the room. Since the speakers are corner loaded, it prevents standing waves which really make the midrange blare/resonate. I found that doubling up the panels in the back of the room (by stacking them on top of each other making a 96" high panel or by doubling up the thickness so that it makes a 24" x 48" x 4" panel) will push it over the threshold where it’s sucking too much sound out of the room. I have a fully carpeted floor, so that is absorbing a lot as well. These are cheap foam panels. I have some Roxul Rockboard 80 on the way, which behave very similar to the foam but with much better bass frequency absorption.

I don’t know which model you have, but the ESL speakers look big, and they might be reflecting sound waves as well as generating them (I don’t know). I’m not sure about putting absorbing panels behind them, unless you put them up towards the ceiling.  Putting absorbing panels behind you sounds like a good idea (since you are so close to the rear wall). Maybe also look at points on the back wall where the speakers are directly aimed at and put absorbing panels there? Or maybe diffusion. Different things to try, lol.

Thanks auxinput. My ESL (old Quads) and magnetic-planar (Magneplanar Tympani T-IV) speakers don’t splatter much sound on the side walls, having the dipole null on either side and being pretty directional at higher frequencies, with the tweeter strips pointed directly towards the listening position at the mid-point of the opposite wall. They will be 5’ from the wall behind them, so diffusion should allow the rear wave to blossom well (one of the best things about planars imo), no need to absorb it. I’m not planning on getting actual real diffusers, having enough LP’s (about 3500), CD’s (around 6000), and books (if I can fit them in!) in racks to pretty much cover the room’s walls.

Thanks for the link Brad, but I don’t see it on my screen. Is it just me?! I need only to cover with absorption the 4’ x 4’ space behind my head on the wall which the listening chair has to be up against, unfortunately, to be able to get the planar speakers 5’ from the wall behind them, a higher priority to me than the lp.

Appreciate the help guys---Eric.

Hi Eric

My Room A is enclosed on the outside of the drywall with Roxul Safe N Sound. The Ceiling and two walls. This was done to insulate the room sounds from the rest of the house. The other two walls are against the house walls with regular insulation on the other side of the drywall.

Something to consider, just throwing it out there.

Curtains of various heavy and light materials work and look good. I am using them extensively in the adjacent room. You could hang one ceiling rail behind your listening chair. Curtains, offer the extra advantage of hiding extra speakers. :^)

You could also use one Magneplanar Tympani speaker behind your chair right now - try it. They absorb. I know guys with Acoustats doing this.

Cheers Chris

Thanks again Brad, and howdy neighbor (sort of)! I’m pretty regular at Music Millennium, but hearing of Jack Pot and Artichoke is great news. I haven’t done much exploring in Portland yet, gotta get into it. I lived in Portland in ’77-8, and all the small records stores selling import LP’s and 45’s back then were gone when I got back up here last year, no surprise. But Music Millennium survives! My record store in L.A. was Amoeba, a pretty amazing place.

I’ve been to The Aladdin, saw Joan Osborne last Summer---great room, great show! Hey, if you have nothing better to do this Friday, I’m playing at JB’s Lounge at The Red Lion in Jantzen Beach, next Friday at Vinyl Tap in Milwaukee, and on the 21st at Laurelthirst on NE Glisan. Say howdy, I’ll buy ya a beer!---Eric.

Thanks everyone. Home depot sells and stocks the Roxul 3" Safe 'n' Sound in a 12-pack of 15-1/4" x 48" panels for $46.27. Such a deal! Lowes sells them in the 24" width, but with a three package minimum. WAY more than I need.

Here's another question: Should I try absorption on the rest of the back wall (behind the listening position), not just directly behind my head?

At $47 for a 12-pack, you can just stack them up in the back of the room to see how it will affect the sound. They 15-1/4" are cut to fit between house frames. If you don’t mind putting up 3 panels instead of 1 or 2, it can be a cheap way to go. The Roxul are only 2.5 lb density, but they might be stiff enough to lay up against the walls. If you do this, be very careful. It is mineral wool fiberglass and always use a filter mouth mask and gloves when handling them.  There's a point where there will be too much absorption in the room.  You'll just have to experiment until you find that threshold.

The panels from ATS Acoustics are mounted in a light wood frame and wrapped with fabric. At $55-76 per panel, it’s really cheap for the build labor. Unless you are fine building them yourself.

Nah, I’ll make one frame sized to fit three pieces of the Roxul in, 45-3/4" x 48" interior. There is 56" between the two doors that flank the listening position, on the wall opposite the speakers. I might put a Roxul strip on each of those doors too, if they prove to be reflecting too much sound over to the lp. The space between the doors and the side walls is far enough away from the lp to be of no concern to me. That’s all the absorption I want---just to kill the first reflection from the speakers pointed at the lp wall.

The room sounds fine overall, no glaring problems as far as I can tell. I have ASC Tube Traps and a DSPeaker Anti-Mode for low-frequency eigenmodes, and MG CornerTunes and EchoTunes for any slap and flutter echo emanating from up near the ceiling. The wall behind the speakers will remain reflective---fine (in fact, preferred) for dipole speakers, as will the sidewalls---no need, due to dipole cancellation. First, I’m painting the room, this weekend, hopefully. I chose Sherwin Williams "Mink", a combination of gray and brown that is absolutely beautiful!

One thing to know about the acoustic materials is that you need massive amounts of thickness if you want to absorb a lot of the lower bass frequencies. Yes, putting a space behind the fiberglass will help because the sound will bounce off the wall and back into the fiberglass. However, if you want to absorb the lower frequencies, you’ll need a very thick trap (like the 6-7" bass traps from GIK). If you want to put multiple layers of the fiberglass in, you need to keep them at the lower densities (like 2.5 - 3 lbs).

I chose the 2" thick 8 lb Roxul because I wanted to limit how much mid/high frequencies it would absorb, but I still wanted decent bass absorption. At a certain point, the denser material will start reflecting sound at a thickness level. A 4" stack of the 8lb Roxul will probably not work any better than a 2" stack. However, putting a 4-8" stack of 2.5lb Safe-n-sound will absorb a lot more bass (as well as a lot more mids/highs).

I didn't expect the extra space behind the panel to turn it into a bass trap! Just to lower its effective absorptive range a little. In the specs chart, it looks as if the Rockboard 60 may be a little better at higher frequencies than the 80, though the difference is marginal and perhaps insignificant. I don't want to over think this! But since the listening position has to be right up against a wall (to allow my dipole speakers to be positioned 5' from the wall behind them), and low-frequency eigenmodes run along room boundaries, absorption at as low a frequency as easily possible would be nice.

So I went to Home Depot last night, and though the HD website stated that the branch I went to had Safe 'n' Sound in stock (even the number of packages), I couldn't find any on the shelves. The HD "dude" couldn't even find it in the stores computer, telling me any acoustical product would have to be ordered. I went in to look at the stuff, to see if it is soft and loose like fiberglass insulation, or stiff like OC703. So Monday I'm going to Lowes, whose website indicates it has 2' x 4' Safe 'n' Sound in stock. We'll see!

I had to google around and think about this question. There really wasn’t a good answer, but...

Putting an air gap behind the panel is not going to absorb more mids/highs that are already being absorbed -- unless you pull the entire panel away from the wall. This allows mids/highs that are coming around the panel to reflect off the wall and into the back side of the panel.

I have read that an air gap behind the panel will enable the panel absorb bass that is an octave lower, but remember that any bass waves going through the panel are going to resonate the wall as well. If you look at the difference between Owens 703 2" and 4".  You’ll see that the 4" thickness is 5 times as affective at 125 Hz (0.17 vs 0.84). Based on this, I’d stack two layers of 3" to make a total of 6" if I wanted to absorb more bass. The "air gap" is really just a tweak to boost bass absorption on thinner panels.

All good points, guys. My desire to get some absorption of lower frequencies at the listening position originates from having read that bass modes/nodes build up at not just room corners (though that is where they are most prominent), nor not just also along all the rooms wall/floor/ceiling intersections, but also along the wall itself---sealed rooms sound "bassiest" against their walls.

I know it takes a whole lotta material to absorb very low frequencies (below 100Hz), so perhaps going beyond the 2-3" of typical absorptive wall panels would bring marginal improvement in that regard. I have room to place a 9" ASC Tube Trap at either side of my chair, so I could do that and set the wall panels atop them. The rooms two front corners (behind the speakers) will have 11" Traps stacked on the big boys---the 16 inchers, the rooms back corners stacked 9" Traps.

Thanks again ya'll---Eric.

Yes, that is true.  There can be a benefit to putting bass traps in the middle of the walls.  However, you will only be able to attack some of the axial room nodes (not all).  It's still a benefit, though.  The link here does a room node calculation for my current HT room:

http://amroc.andymel.eu/?l=17.5&w=11.25&h=9&ft=true&r60=0.6

If you move your mouse pointer over each of the axial room nodes (the tallest lines on the frequency chart), you'll see in the "Room 3d" graphic that some nodes will build up on the front/back walls, some will build up on the side walls and some will build up on the ceiling/floor.

Interest article I found here:

http://ethanwiner.com/density.html

Where Ethan Winer found that putting Twelve 3" 703-FRK panels in a room absorbed more bass frequencies than Six 6" 703-FRK panels.  These are frequencies down in the 40-80Hfz area.  Makes me think of using the 703 FRK instead, because my room is becoming a little too dead with the Rockboard 80 panels even.

Exactly so Spencer. I have a dedicated room and answer to no one but myself, but I have a fairly developed sense of aesthetics myself, and a desire for a nice looking environment in which to listen to music. I don't have to build any "real" bass traps (one of the disagreements between Ethan and Jon is in regard to what qualifies as one), as in the mid-90's I found thirteen of them, in sizes 9", 11", and 16", for ten bucks apiece (!) in The Recycler, a Southern California weekly "for sale" newspaper.

The music room in my new abode forces me for the first time to sit very close to the rear wall, hence the need for treatment of that wall. I have prioritized having my planar speakers 5' from the wall behind them over the listening position being away from it's wall, as the rear wave of planars really must be delayed at least 10ms behind the front wave, and distance from the wall behind them is the only way to achieve that. Ethan and Jon (and ya'll here on Audiogon) are giving me the info I need to do the rear wall "correctly". Thanks again!---Eric.

Happy New year Spencer. I'm still getting use to this Northwest weather, quite different from that of the California desert I spent six years in before moving up here. Everything is frozen in the morning! It's dark and cool all day during the Fall and Winter, which I'm really enjoying after being in blinding light and heat for six years. No more skin cancers! I've spent a lot of time on California beaches, and have paid the price.

I bought a nice piece of 1/2" X 2' X 4' plywood and cut it in four equal pieces 6" wide, from which a 6" deep frame measuring 4' square can be assembled. I then got a bag of Roxul Safe 'n' Sound, which contains twelve 3" thick pieces almost 16" wide and 48" long. Three pieces fit inside the frame, and two layers completely fill the frame's 6" depth. Perfect! One bag is just enough to make two absorptive panels, one of which I will position on the wall right behind my listening chair. I'll place the frame on top of a pair 9" Tube Traps butted up against that wall, and the combination of the Traps and panel should mitigate both reflections off the wall and the bass mode (present in all rooms at wall/ceiling/floor boundaries) at the listening position. I haven't done it yet, but Spring isn't that far away ;-) .