MarkEdmonds wrote:Bob - The offer of a loan of an electric carving knife was withdrawn when I said what I was going to be doing with it! I dunno, sometimes it is better to be economical with the truth!
Paul - when you get to do some awkward shape cuts, try the type of saw I've been using - trust me, it is hugely easier and more accurate than a bread knife. You get twice the cut per stroke due to the length of the blade and due to the height of the blade, it doesn't wander. Also, the tooth density is higher so it doesn't pull the rockwool as much as a breadknife and you get a cleaner cut.
When you walk into the room, you wouldn't know it is on.
IN fact I shall be cutting TUNNELS in bass traps to accompilsh this, so the WHOLE CORNER TRAP ( Studiotips chunks ) will act as a duct silencer.
Bob wrote:Paul:IN fact I shall be cutting TUNNELS in bass traps to accompilsh this, so the WHOLE CORNER TRAP ( Studiotips chunks ) will act as a duct silencer.
When there's rockwool surrounded by wood/gypsum I can see how it absorbs. But if there's no wood/gypsum, won't sound just go through the studiotips chunk into/outfrom your room?
Your box around the fan isn't a "box in a box" the way Paul's is rumored to be, but as long as it works !When you walk into the room, you wouldn't know it is on.
Someone over at RO once posted that they had a fan control switch in the room, and turning it on or off they couldn't tell that there was a change audibly, although there was airflow (paper taped over vents moved).
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Porter-Cable CFFN250N Finish & Brad Nailer Combo Kit
Porter-Cable US58 22 Gauge, 5/8" Upholstery Stapler Kit
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Paul Woodlock wrote:Mark, I'm assuming your 'duct silencer' ( top thinner MDF box ) has the airflow in direct contact with the rockwool ( Except for cloth maybe? )
It looks a great job mate. I bet your real pleased with the SILENCE!!!
YOu could quieten it even more if you were to take more than one duct from the duct silencer to teh room. This is because you double the cross sectiona; area of the duct and thus, halve the air velocity. This is what I would have done, and in fact doing on my build.
I shall be at least quadrupling the duct area where they enter and exit the room. And although I have HUGE Silencers to take care of Isoaltion issues, I will also be using secondary duct silencers as well. IN fact I shall be cutting TUNNELS in bass traps to accompilsh this, so the WHOLE CORNER TRAP ( Studiotips chunks ) will act as a duct silencer.
You could do that yourself. Simply remove the plastic duct from the vent to your MDF duct silencer,and use a carved out tunnel in the Corner trap.
regarding my fan box, it's not only a box in a box, I also made flexible couplings out of leather between the two boxes from a pair of womans discarded trousers. Maximum isolation
The INNER box also has 4" of concrete poured in the bottom to increase mass-spring-mass.
I'll post some piccies so you can get the idea.
Sound drops (TL) through a layer of gypsum by several orders of magnitude in energy.
Sound drops (TL) through a layer of rockwool by a half an order of magnitude.
I think your corner trap ducting idea is an 'experiment', and that it'll leak sound near the out-of-the-room end.
You're the king of box-in-a-box. How loud was your fan when you just wrapped rockwool around it (without wood)?
Paul - yep, silencer box is 1' x 3' lined with RW3 and the duct attached to top and bottom. Works really well. It was modelled on the diagram you sketched out on that sheet of MDF
I wanted to use the entire corner trap for the silencer duct but couldn't come up with a neat way of drilling the tunnel. The biggest hole saw I have is only 65mm and this would need to be 120mm and then there is the extension bar length. How are you going to drill through many feet depth of RW3 to get the tunnel perfectly in line?
I can only assume you will do it slab by slab which means you have to get them all aligned perfectly once bored. With the power of fan I am using, any unevenness in the tunnel would reduce air flow - perhaps with your fan (which looks like the back of a jet engine!), this wont matter?
could you explain further "out of the room end"? I'm not exactly srue what you mean by this.
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