shoping for Johns Manville today, could use some help

[daav]

OK so i found a place in VT that sells Johns Manville insulation (no one i called seemed willing to help much with OC 703 at all). One thing i can say is when dealing with local suppliers, to try to not mention the noise reduction aspects of the stuff, it seems to confuse things if they don't know it for these uses already.

So anyway, i am going to run over and check it out today, and had some last minute clarifications i wanted to make:

They didn;t seem to be aware of the "800 series" that i have seen posted about, has anyone esle bought this stuff that they can help define the model i should be looking for?

Similiarly, if i am looking for a certian density/cubic foot, and am dealing with fiberglass "board" will i have pretty good luck getting good noise reduction if i have to wing it? i.e. if it looks like rigid and walks like rigid, will i have a good shot?

Is mineral wool all pretty much the same stuff? I have seen good noise reduction there.

last, has anyone had to buy the foil or paper backed rigid? if that is all I have available is it possible or reasonable to remove the backing to improve the noise reduction?

PS i have read a ton on this, but info is all over the place, i want to be armed well when i go browsing today. I will update the "where to find" thread when i can verify that they have the good stuff for the 4 VT people on the boards.

Daav

[FALKEN]

yeah you can't get Johns Manville without the foil. I just leave it on...and put it towards the wall. look here to find the weight and absorption coefficient you want...

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

I think I went with the 2" 814. For bass traps I built 15" airtight tubes.

[daav]

Originally Posted by FALKEN

yeah you can't get Johns Manville without the foil. I just leave it on...and put it towards the wall. look here to find the weight and absorption coefficient you want...

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

I think I went with the 2" 814. For bass traps I built 15" airtight tubes.

Thanks for that.
Any info around here anywhere on the tubes you built? I haven't come across it yet.

[RICK FITZPATRICK]

For bass traps I built 15" airtight tubes.

Could you describe exactly the design of these "tubes", and by what principle they become low frequency absorbers, or where the design came from. I'd be interested in seeing this. And what do you mean by "airtight". Resistance absorption needs an exposed surface to the air in order to work at optimum. Yes, batt type insulation will absorb within a wall, but that is because of transmission of vibration into the airgap, which is .....well, filled with insulation. Membrane absorbers work by resistance to resonance vibration, which transforms mechanical energy into heat. TUBE TRAPS, which is a proprietary design whereby a wire frame is formed into a tube, and fiberglass or other absorption material is inserted on ONE HALF the tube, with a reflective face to the outside. When placed in a corner, the reflection from the corner is theoretically aborbed by the fiberglass facing the corner. This is actually broadband resistance absorption as the fiberlass is no more than an 1" thick. However, how do you make a tube shape made of wire, and exposed to the air, "airtight"? Thats preposterous. Thats why I asked how your "tubes" are constructed, and by what principle they become absorbers at low frequencies.

fitZ

[Ptownkid]

My guess would be that they were built based on some bad internet advice.

learn first, build second is always the best route.

[RICK FITZPATRICK]

My guess would be that they were built based on some bad internet advice.

Could be. I've probably been guilty of spreading "net fact" one time or other myself. At least untill I learned that not all you read on the net is indeed fact. Now, I TRY to limit my suggestions to what I have researched to the point of satisfaction with its integrety. Still, I also try to include this DISCLAIMER usually. I AM NO EXPERT!!
I've been "put in my place" so to speak, a few times by real experts, so I've learned not to overstep my bounds as to knowledge. Yea, I still guess once in a while, and extrapolate once in a while But if its wrong, I know I'll hear about it. The real data on acoustics and isolation can be found if you know where to look. One of the best sites around for truth in these matters is here...
http://forum.studiotips.com/index.php

fitZ

[FALKEN]

no, I assure you that these things work. they're ingenius, and have even been discussed on this board. you get a fiberglass cylinder, and cut out a top and bottom using 3/4" MDF. you then glue the top and bottom using liquid nails and make the thing airtight. when the bass note is played, it increases the pressure in the room (in the corners, around the tube). so there is more pressure outside of the tube than inside of the tube. since these pressures want to equalize, the sound is "sucked" into the tube through the fiberglass. here are some links:

http://www.teresaudio.com/haven/traps/traps.html

http://homerecording.com/bbs/showthr...diy+tube+traps

I didn't use the blind decorations, I just stapled the fabric to the MDF in two layers. the reason for putting plastic over half of the tube is so that you do not end up with too much high frequency absorption from the sheer amount of fiberglass involved.

[daav]

I bumped that thread because these things just look too easy (and portable) to make.

Anyone who has all sorts of fancy expertise review this stuff to second that it seems like a great idea?


daav.

[RICK FITZPATRICK]

(in the corners, around the tube). so there is more pressure outside of the tube than inside of the tube. since these pressures want to equalize, the sound is "sucked" into the tube through the fiberglass. here are some links:

I smell snake oil. I think you should read this.
http://forum.studiotips.com/viewtopi...ight=tube+trap
At least in regards to these specs.
http://www.asc-hifi.com/products/tt-technicals.htm

Then compare to this

http://forum.studiotips.com/viewtopic.php?t=536


At least you weren't "sucked".into this
http://cgi.ebay.com/Studio-Acoustic-...QQcmdZViewItem
fitZ

[FALKEN]

whatever rick those links don't mean anything.

[HapiCmpur]

Originally Posted by FALKEN

yeah you can't get Johns Manville without the foil.

Not true, my good man. Not true. Johns Manville 817 has no backing of any kind. You can get it in several thicknesses (Mine is 2") and, as I recall, it's 6 pcf.

Wish I could help you, Daav, but I'm pretty sure my supplier, McCormick Insulation Supply, only sells in PA and MD.

[RICK FITZPATRICK]

whatever rick those links don't mean anything.

Which ones, the ones you posted or the ones I posted.

[FALKEN]

Originally Posted by HapiCmpur

Not true, my good man. Not true. Johns Manville 817 has no backing of any kind. You can get it in several thicknesses (Mine is 2") and, as I recall, it's 6 pcf.

Wish I could help you, Daav, but I'm pretty sure my supplier, McCormick Insulation Supply, only sells in PA and MD.

ok I stand corrected.

[FALKEN]

Originally Posted by RICK FITZPATRICK

Which ones, the ones you posted or the ones I posted.

man the ones you posted. all they say is "we don't know". one of the links was a guy who said he tried it and didn't hear a difference. this kills me for 2 reasons. 1 - he didn't have it airtight 2- its got to be at least as good as a 2" panel across the corner if not better, even if the sound isn't "sucked" in there. one of the links even said that they do work, and gave frequenices down to which they are effective at certain diameters.

I got the idea from a local studio that uses them and said that they're great. tons of people use them.

But what I really mean to say is.... I came here not knowing anything. I came here not believing the usefulness of acoustic treatment. I pleaded for proof! I decided to give it a go because I couldn't afford not to try it, if it really works that well. I settled on these bass traps, a few wall panels, a few gobos, and a few spot treaters on mic stands. I have experimented a little bit with them, and still have more to build, and more experiments to do. and I still don't know much. I do know my mixes got better. I also know that when I used the spot treaters, my vocals got a lot drier. so it wasn't all bull. I would like to know if these tube traps are bull or not. I would listen to anything you have to say because I do NOT know it all, or really much of anything at all about this topic. not as much as the other folks here. I am just starting out. But my opinion so far is that they are not bull, and these articles are not very convincing to the contrary.

Anywayz, they're 3 feet tall and stackable so I have 6' of my 8' ceililngs filled..which is pretty good. I also didn't have to put any holes in the wall to mount them, and If I want to bring them in another room to record with they're totally portable. I haven't compared with the flat panel design, but I guess I could A/B it pretty easily, I've got them mounted on mic stands. Spend too much freaking time on this board instead of experimenting.

[daav]

Originally Posted by HapiCmpur

Not true, my good man. Not true. Johns Manville 817 has no backing of any kind. You can get it in several thicknesses (Mine is 2") and, as I recall, it's 6 pcf.

Wish I could help you, Daav, but I'm pretty sure my supplier, McCormick Insulation Supply, only sells in PA and MD.

Well, i found 817with a foil backing, that pulled off cleanly with no issue, so i got my choice. Ironically, there was a woman before me who bought all but one piece of the 2" 6pcf 817they had to soundproof her home theater. I thought I was the only one around these parts that ever heard of this stuff!

I made do with that and a few 1.5" versions and just used three layers, a bit of overkill at 4.5" but i was feeling impatient. Just for kicks i also got a 3 foot length of the pipe insulation, and tonight i built one of those tube traps. It is drying now, I hope this thing works as well as advertised, either way, like Falken mentions, it is a convientient package for some bass trapping, even if there is not magic physics at work.

Daav

[travelin travis]

Originally Posted by FALKEN

Spend too much freaking time on this board instead of experimenting.

that's all any of us can do. experiment and see what works and what does'nt. how well are they working? i think some people around here are too quick at trying to rip apart ideas that deviate from the most popular way of doing things.

my question is, why would'nt these tubes work? what's so different in this tube idea and the more popular panel idea?