Cold air return duct problems????

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Ginzoo

Ginzoo

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I am midway through building my project studio in the basement.Everything is cool EXCEPT the duct that runs through the middle of the room just below ceiling height.
I am worried that sound will travel to other parts of the house unless I take DRASTIC measures to somehow stop the sound.Its 8"x12"-8ft long and it cannot be removed because of location.Can I make it less prone to reverberation.It picks up every sound I make and sends it all over the house.I have not finished the ceiling yet because of this problem.
Any ideas? Ginzoo
 
1. Line the inside of the duct with insulation to stop the sound travelling down it.
2. Box it in if possible.
cheers :D
 
Replace it with that soft, flex type of conduit. It looks like a giant slinky rapped with insulation with a layer of plastic around the whole thing.
 
Thanks guys.
Do you know if the flexible stuff comes in a large enough diamater to move that amount of air?
I just want to do it right the first time before boxing it in.
Ginzoo
 
The stuff I bought is 12" in diameter.
 
even that won't work as well as boxing it in
cheers :)
 
John,
Whatever way I go,it will be boxed in with layers of OSB and drywall.I just want to make sure that I stop a BIG problem before it gets enclosed.Im trying to eliminate as much sound going to the rest of the house as possible.It seems that every surface I touch costs twice as much as I had planned just to eliminate excess sound{mostly bass/percusion} going to the rest of my house!!I've got my gear,I want to start recording in this lifetime but keep getting set back by a BUNCH of little things like this.
Thanks for your input.
Ginzoo
 
Cover all your registers with lots of blankets. Still hearing the sound? Probably not the duct. Just an idea.
 
Hey. Another idea. The flexible "slinky" type ducting probably won't resonate bass as much, and is pre-insulated (maybe enough so you won't have to wrap it). We're probably assuming you're referring to that galvenized steel [X] paneled-ducting (you know, that diamond shape they always seem to put on that ducting).
 
Ginzoo - that's the studio building game - stopping sound is expensive. The builder today said he has used 7 bags of plaster (mud??) so far in the studio when a normal house uses 3. :)

cheers
 
Yea John, you definatly should box in the duct as well but the flex stuff really slows down sympathetic vibrations.
 
I checked out the flexi stuff last night.It should do the trick.About $20 for 12"x25'.Not as expensive as I thought.
 
I also had the same prob as you Ginzoo.I first insulated the offending duct, boxed it in against the upper right wall, then placed additional padding to nullify and and all sounds traveling thru the house. Fortunatly,I am building my room opposite to the duct,but did not want to take any chances with it!
 
OK,I bought the flexi.stuff.I put it INSIDE the duct and hooked it up at both ends with the correct "transitions".Air movement is about the same as it was before.I put two layers of foam covered with aluminum{cant recall the name,comes in 4x8 sheets}attached that with liquid nails.It is framed in and ready to be boxed in with osb/dry wall layers.Right now it sounds deader than John Kennedy!!!Now I have to come up with money for MORE drywall.Why is that stuff so expensive lately?{or am I just a tight-ass/cheapskate}.
Ginzoo
 
All the boys say you are a tight-ass:) It will work fine Ginzoo when you box it in. That stuff you got with the foil is the stuff I refer to as Insulco. Over here it comes in plain , with foil, or with a black cloth backing. That's what I'm using (in the black 2" version) on my walls. ;)
 
Sorry that I havn't gotten in on this one yet. I've been kind busy lately building my own studio.

Go check out http://www.greysfiles.com/Studio/Index.htm and click on "Greys Studio" and see what I did for my ventilation trunks. In the first picture you can see half way down the ceiling there's a beam, right behind that are the two trunks. You can see how we have the ceiling to beam made into a 45 degree angle with studs. We did the same thing on the other side of the trunks. In the second picture you can see directly at the top of the picture is the box we built around it from the underside. It may look like the 2X4's are touching the metal, but I floated the trunks from the joists with rubber straps. If you hit the ceiling joists with a hammer, or the box around the trunk, the trunk doesn't vibrate AT ALL. That's pretty important. You can see the box from another perspective in the third picture, and a couple of the other ones. We're now looking into making the straps that floated the turnk even stronger, by putting more on it, and covering the entire outside of the trunks with the cutt off drywall. It will keep it from rattling, and it will keep a lot more sound out.

We didn't replace the trunk with the flexible duct, that would have taken a bunch more inspections from the building inspector, and it woul have cost a ton more money for that permit. The one we got was only $50. We did, however, replace all the branches going to the rooms with 6" flexible duct. That stuff is the studio builder's dream pretty much. It doesn't carry sound at all, and it insulates the space it's in. The only place you have to worry about sound getting through is the place where the hole is cut for the vent, but you have to worry about that anyway, so why not just use the flexi-duct.

Speaking of flexible things... we were running the conduit last week for our mic plug-ins for all the rooms, and we ran into a problem. How do you make a 10' piece of conduit go against the joists? We though, "well, maybe if we cut it into a bunch of little pieces..." but that was a TON of extra work, and time. So then flexible conduit poped in my head, I use it at work all the time. So we went out a bought some and it worked great. So, if you're running conduit in your studio and you have problems like the one I refered to, I just gave you your solution :).

Later,
-Brian
 
Good advice Brian - we laid pipes in the slab by cutting the slab with a concrete cutter etyc - big mess with all the water involved. Then it was decided to have timber floor!! now we can lay the cables under the floor!! :rolleyes:

With regards foam I realise now you actually mean foam rubber. Foam rubber is not a really effective absorber unless it has been specifically designed to do so - usually by cutting a wedge shape in the surface which increases it's absorption factors. You'll see it on the back wall of the control room in the Music Farm. (incidently I didn't specify it - it was added later by the owner - we didn't redo the control room in the last update. I would have used multiple layers of wool - they won't allow fibreglass in the building)

control_room.jpg


The other alternatives are fibreglass, rockwool or dacron also in OZ we have the option of wool. Fibreglass in it's compressed form is the the best without doubt followed by rockwool. The dacron batts are good but require to be thicker than fibregalss, i.e. 3" dacron is equal to 1" compressed fibreglass. Wool is about the same as Dacron. All the insulation in our walls etc is dacron purely because it is cheaper and the workmen will work with it. Lot's of builders these days will not work with that much fibreglass and I don't blame them. ;)

Cheers
John
 
John,NOT foam rubber. I dont know exactly what the chemical make-up is.The name on the sheet is"Super Tuff Insulation".Very dense.I dont remember who mfg.it.It is covered with drywall already so I cant go downstairs to look.Whatever it is,it did the trick BEFORE I covered it with all of the finishing layers!That is what I was trying to acomplish.
Brian,I have been checking out your/John's site as well as John's homepage.I have lifted SO MANY ideas from the two of you that has either 1. saved me a lot of money or 2. COST me a lot of money by doing the right thing the first time and eliminating sound from escaping my little studio.I wont tell my "non-musician" buds how much this is going to cost in the end.They already think I am crazy for doing this but they cant wait to come play with all of the fasinating toys.
Thank you all very much for the ideas/input!!
Ginzoo
p.s.Cool picture,John.{I think I need to do ANOTHER re-design}. ha!
 
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