Mineral Wool or 703? $$$=Difference?

[joelmoore]

I posted this on another thread that's going unnoticed. I have to buy something this coming week. What Would TapeOp Do?

This material http://www.atsacoustics.com/item--SAFB- ... -1006.html is much cheaper($36.00 - 6pc) than this material http://www.atsacoustics.com/item--Owens ... -1004.html ($74.00 - 6 pc).

Is there enough difference in absorption property to warrant my choosing the higher cost option?

My plan is to build as many 4" panels as I can within a $600-$750 budget. Three of my four corners will be covered from floor to ceiling(one is obstructed by my entry door). The wall/ceiling corners will be covered their entire wall lengths. And in a few select places the open flat wall space will be covered as well.

I can make up to 14 or so panels with 703 and around 28 or so panels with mineral wool. Am I just making more work for myself using mineral wool instead of 703? Am I going to end up with the same or negligible effect using 703 minus the additional work?

What Would Tape Op Do?

[Jed]

Here is the bible for understanding how these two materials differ:

http://www.bobgolds.com/AbsorptionCoefficients.htm

The biggest differences performance-wise exist at frequencies below 250hz, but even there both products work very well. Other than that, the SAFb will be a little floppier to work with. But as you noted, you can get a lot more rock wool for the same price, so that means you can either make more, bigger, or different traps.

You might want to take a look at building "superchunks" in the open corners...I built them in the corners of my studio and they work really well. It'll give you better performance than 4" straddling the corners:

http://forum.studiotips.com/viewtopic.php?t=535
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=7278
http://forum.studiotips.com/viewtopic.php?t=536
http://messageboard.tapeop.com/viewtopi ... &&start=15

Good luck!

[JWL]

Jed's got it right. Sound wise, the 2 materials are more or less interchangeable. But given the price difference (ie, the same budget gets you more than 2x as much rockwool), you can get much more absorption by spending the same cash on rockwool than you can on 703.

The main disadavantage to rockwool is that it is harder to work with, its edges aren't as sharp, and it will crumble some when you cut it.

If you don't mind that, then def go rockwool.

[JustinHedrick]

does rockwool fibers get in your skin the way fiberglass does, or is it safer to use?

[joelmoore]

Hi,

I just got a quote from a local(Nashville, TN) insulation supply warehouse and it goes as follows:

Mineral Wool:

4lb - 2" - .45 p/sq ft
4lb - 4" - .90 p/sq ft
8lb - 2" - .54 p/sq ft
8lb - 4" - 1.08 p/sq ft

OC 703:

2" 1.08 p/sq ft

These are all quotes for 2'x4' sheets that come 6 per bundle (no bulk rate discount).

My question is this. Does the 8lb 4" Mineral Wool @ 1.08 p/sq ft provide any advantage over the OC 703 2" @ the same price? Or vice versa? Besides the 703 being easier to work with.

It seems for floor to ceiling Superchunks where height is part of the equation that the 4" Mineral wool would be the more advantageous option.

Would anyone take issue with using the 4lb 4" for first reflection panels or clouds? Would I be better off using the 8lb 2" for this purposes?

[JWL]

I'd have to look at the specs to be sure, but most of the superchunks proponents actually say you should use the less dense material for two reasons: first, it's far less costly, and second, it will actually perform a bit better in the extreme low end.

Good news for once, huh?

If it were me, I'd probably go with the 4lb 4" wool for the superchunks, and 4" 8lb for the RFZ panels.

[JWL]

To answer your specific question, yes 4" of mineral wool is better than 2" of 703.

I tried to get a link to the superchunks site where they talk about less dense materials, but the studiotips forum site seems to be down at the moment.

[joelmoore]

I tried to go to the studiotips site earlier and also had difficulties.

I was looking for that diagram of how to cut the triangles for superchunks.

I'm still trying to decide whether to go with 2 superchunks and 2 6" (broadband absorber) panels or just do all the corners with 6" panels. I have enough budget for both now. So that's not really the issue anymore.

I know you said previously that it may be better for me given my room layout and budget to just go with panels all around. But I'm kind of leaning back toward throwing in 2 superchunks just for good measure since my budget can handle it now.

??? What do you think ???

[JWL]

There are 2 ways to cut the panels for superchunks. One way yields larger triangles, and they will perform better, but of course you need more materials.

Here, cut a 2x4 panel in half, so you have 2 - 2x2 panels. then cut each 2x2 panel in half diagonally. This will yield trinagles that are something like 31" wide. Stack these in the corner.

The smaller version, cut each 2x4 panel in half, then cut each 2x2 panel TWICE diagonally in an x pattern. These will yield triangles that have 24" wide materials pointing into the room.

[joelmoore]

Wish me luck folks...

I'm headed down to the insulation supply place this morning to pick up a couple bundles of Mineral Wool.

I feel like I have thought this thing through enough now to go and spend some money. I've decided to buy 3 bundles to start. Since the place is close to me I can go back when I need more and I don't have to wait on shipping and such.

I'll be building my very first superchunk today!!! BTW, is that where the band came up with their name? Superchunk? I can't imagine this as a coincidence. Who knows?

I'm going to take some pictures to post as a record for any newbies to come. This forum and the dedicated, generous folks that contribute to it have made me more knowledgeable and confident about the choices I'm making for my studio. And I'm eternally grateful for that. Keep up the great work TapeOpers! And to the TOMB keepers too, thank you for all the work that you have done and continue to do to spread the art and craft of audio recording. What would the world be without sound?

[digitaldrummer]

I didn't do the superchunks, but did build my own bass traps from SAFB mineral wool -- http://www.digitaldrummer.net/basstraps.htm

as said earlier, it is floppy so you need a wooden frame around it, but still cheaper than OC703.

Mike

[joelkriske]

so what was the result with the mineral wool?

i have built traps with it myself, and it seems pointless to try to cut it (not rigid enough). still built some great frames with it that are serving me well...

[joelmoore]

I'm still working on the room and will post all my pix and descriptions when I'm done. But as for the Mineral Wool...it's great. I had no problems cutting it. And it's held up just fine for use in superchunks so far. I have one superchunk finished and it already has made a difference in the clarity of my toms. The room still has a long way to go before it's ready for prime time but it's on it's way. And with the lower price I think I may just end up spending less than I had anticipated.

So far I bought 5 bundles (4 sheets p/bundle) 4" 4lb 2'x4' MW @ $144 tax included. and 2 Bundles(3 sheets p/bundle) 4" 8lb 2'x4' MW @ $51.84 tax included. I have spent another $100 approx on hardware, tools, fabric and wood. I will likely have to buy more wood.

I'm going to post a detailed breakdown of my spending along with pictures of the chunks in progress to completion when I'm done. It may be next week though before I get to all that.

[darjama]

If you don't have a fabric store near you and want to order some burlap to cover your traps, there's a 50% coupon for Joann.com, APRA750, good until the end of the month.

they do hit you pretty well on the shipping charges though.

[joelmoore]

I may be cutting my nose off to spite my face here but for fabric I just went to Goodwill and bought $12 worth of bed sheets. Lot's of colors to choose from and easy to work with. Finished one superchunk so far and the linens seem to do the trick. Anyone take issue with that?