Ive Been Planning This Garage Studio for 10 Years!

#46

GraGra wrote:Source of the post Hi guys, thanks for the feedback. That's a bit of a concern about the Yellow Tongue!
My builder and Engineer said it was OK as long it was behind a moisture barrier, and well.. I've gone ahead and used it. Now I'm worried! Is there any extra precaution I should take at this point?
IMG_9733.jpeg

Graeme
The primary issues with yellowtongue and moisture are the edges and screw/nail penetrations. If you have a well installed moisture wrap and the fibre cement outer is well sealed the only other concern I'd have is moisture coming up from the bottom. If you have that covered, you've taken as many steps as you can to mitigate the risk.
Andrew

#47

gullfo wrote:Source of the post i disagree with Rod on this, bridging isolation walls reduces the isolation.

Absolutely agree with Glenn here! (and thus, also disagree with Rod...) Flanking is a very real thing, and can greatly reduce isolation.
When I teach seminars on this (in person), there's a simple demonstration to show what a single nail can do to pass a lot of sound... using an old-fashioned tuning fork (the thing that musicians used to use for tuning their instruments, before electronic tuners where invented). Tap the tuning fork tines on something solid (eg: table edge, door frame, etc), then hold it out at arms length in free air. Ask people a few feet away if they can hear it... (nope!). Tap it again and press the butt end against the surface of the table, widow, door, etc. Can you hear it now? Yup. Loud and clear. The contact area between the base end of the fork and the table, is about the same cross section as that of a large nail. Even that tiny area can transmit a surprising amount of sound.
It's a very compelling demonstration. Even a single nail bridging your leaves can reduce isolation considerably. If you are aiming for high isolation (many home-studio builders are), then avoid all types of flanking as much as possible.

- Stuart -

#48

along those lines: decouple pipes, wires, ducts, etc. electrical - use bends and loops to avoid tight wire connections across isolation boundaries, use decoupled conduits when spanning isolation boundaries. use flex duct or duct decoupler to span isolation boundaries, vacuum up the crud from construction between isolation boundaries, remove extraneous bracing and/or replace with isolation bracing, on isolation boundaries.

there is a pattern here... :horse:

#49

gearjunk1e wrote:Source of the post Graeme
The primary issues with yellowtongue and moisture are the edges and screw/nail penetrations. If you have a well installed moisture wrap and the fibre cement outer is well sealed the only other concern I'd have is moisture coming up from the bottom. If you have that covered, you've taken as many steps as you can to mitigate the risk.
Andrew

Thanks Andrew. Yes I have a mosture barrier in place and the fibre cement is throughly sealed.
however Ive just gone and checked the bottom edge and can indeed see the exposed end of the yellowtongue up behind the fibre cement cladding!
So I will go around make sure that bottom edge is sealed absolutely watertight!

#50

So, its time to revisit the dreaded HVAC issue again

After struggling with this part of the design for soooo long I'm hoping to finally move on. But after the effort Ive gone to in order to isolate as much sound as possible, I really dont want to mess it all up here!!

For the below calculations, I'm only looking at the single-room Recording Studio. (Since the Piano Room has operable windows and isolation is not critical, I will not require separate ventilation, and AC is fairly simple via a mini split.)

Heating/Cooling

https://www.fujitsugeneral.com.au/produ ... astg09kmtc

Ventilation

I'm providing fresh air via separate intake and exhaust vents, and to stop sound travelling through the ventilation, I'll build a silencer box where each vent penetrates a leaf, connected with flexible duct and driven by an inline fan on the intake vent (4 boxes in total).

This first part of the math's I'm good with:

Now this is where it all gets hazy for me, so please correct me where I've gone wrong!!

I'm actually planning on building the silencer significantly larger than this, in the hopes that just throwing more at it will make up for any error in calcualtions (see sketch below)

Questions:
- Does that last section of math and logic sound OK, or have I made a fundamental error in there?
- Is it OK for the fpm to drop down so slow within the silencer before hitting the register?
- Is it a case of "the larger the better" for a silencer box?

Many Thanks!! Gra

#51

your silencer does not have to be the plenum. you could create the silencer effectively with the same area of the duct, then expand into a plenum to get the velocity reduction. you could also create the silencer to vent in both sides to plenums there to make the air flow symmetrical around your desk.

#52

Thanks Glenn. Im not 100% sure what you mean by a plenum, but I'm imagining some type of box that the registers are attached to, large enough to slow the air down significantly so it just kind of falls out of the register silently?
And if I use one of those, then my silencer can just be the same size as my flexible duct?

#53

I'm looking at a couple of different Duct Liner products for lining the inside of the silencers.
Would any of these be suitable? Any reason to choose one over the other?

Bradford Supertel - Rigid Glasswool Faced Boards
https://www.bradfordinsulation.com.au/c ... t/supertel

Bradford Flexitel - Flexible Glasswool Faced Blanket
https://www.bradfordinsulation.com.au/c ... t/flexitel

Fletcher Semi Rigid Glasswool Faced Board
https://insulshop.com.au/product/semi-rigid-board

Knauff Climacoustic - Flexible Glasswool Faced Blanket
https://www.knaufinsulation.com.au/prod ... liner-roll

#54

more like this: https://www.knaufinsulation.com.au/prod ... enum-liner you generally want perforations or other open-face-like absorption, the faced products will produce less resistance but not as much of the MF and HF component absorption which is highly desirable. this product may be workable: https://insulshop.com.au/product/semi-rigid-board/ but i'd be inclined to use the Knauf product.

#55

GraGra wrote:Source of the post Thanks Glenn. Im not 100% sure what you mean by a plenum, but I'm imagining some type of box that the registers are attached to, large enough to slow the air down significantly so it just kind of falls out of the register silently?
And if I use one of those, then my silencer can just be the same size as my flexible duct?

Glenn's advice is spot on here. To my knowledge the plenum is the final point of delivery of the airflow. It can be in the room instead of (for example) buried in a wall. The plenum can have a larger cross section than the silencer, and indeed this is where the airspeed reduction happens.

An advantage of this is that you can have silencers with smaller cross sections that are lighter, easier, cheaper to build and easier to fit in wall & ceiling cavities. A smaller cross section should also attenuate sound better. I *think* Rod Gervais recommended not going above a 20x20cm silencer cross section if you want to have decent sound attenuation, and preferably a little less than this.

When I was building my ventilation I found the main tradeoff with silencer cross section was that the smaller the cross section, the higher the static pressure from it, and therefore a more powerful (and perhaps noisier) fan would be required to get the same airflow as a bigger cross section. When you start doing the theoretical calculation of various possibilities this becomes clearer.

Cheers,
Jennifer

#56

the silencer and plenums can all be in the room :-)

when i'm designing, i typically use wall-ceiling soffits to allow me to route air, wires, lighting etc PLUS get a lot more absorption while freeing up the walls and floor spaces.
here's an example of a silencer in the soffit feeding a plenum centered over the desk. in each step there is expansion. and the return opposite would be similar with the velocity increasing as the duct / spaces contracts.

#57

Nicely described. So in other words, am I correct to think you can have air moving faster than the outlet as long as it's not a ridiculous differential right before the properly sized grille, and the fast moving areas like your silencer are sufficiently isolated to prevent any whooshing being heard?

#58

Yes your air velocity into the silence can be faster speed and then through expansion, slow down, before exiting the low noise vent.

#59

That's brilliant thanks Glenn.

So if the sofits are mounted inside the room ( ie beneath your inner leaf cieling), I imaging you also stuff them with absorption and finish with stretched fabric to provide bass trapping?

#60

yeppers - all of the remaining space is filled. sometimes i layer with 1-2" of semi-rigid (e.g. 703) inside the frame faces, then a layer of MLV, and interior filled with lightweight batts. but sometimes it's too small or costly so i just do the lightweight, cover with cloth, and then add slats and panels on the soffit as needed it the room is too dry (usually only a live room needs this, or a "live section" (producer desk or couch) of the CR).

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