Jack Audio/Visual - Construction And Design Process

[vakis]

Excellent Tom Thank you!!
I've been searching and searching and can't believe i haven't found this!
For the past week I've been doing nothing but search for ventilation silencers

Excellent,
cheers!

[vakis]

Hi Tom,

Great link you gave me there, I've been reading all night yesterday.
Got one question if you can answer.

If I have a round duct of 6" and then i'm going to a silencer that has a square opening let's say.

Will I calculate the sq. inches of the circle and apply them double on the silencer?
I.e. sq inches of Circle Area = pi x radiusxradius.. so 3.14x3x3= 28.2, double of that for the silencer is 56.2 .

So square root of that for a perfect square makes us 7.49" per side of square. (this will of course adjust accordingly to a rectangular to keep all sides added to 56.2)

Feels like I'm back to school... Does this seem right?

And is this also the way to see the size of square ducts that interconnect with round pipes? Just not double like the silencer?

The more I read the more confused I get

Thanks,
Vakis

[TomVan]

Holy crap too much for the noodle.
6" duct
12" box
That would be the easiest way I would calculate.
Peace
Tom

[vakis]

OK, so here's my take on silencers. Please correct me if I'm wrong, and if you can please verify if I'm right.

-I will probably use short length of flex duct just to go through the walls, so that I have no mechanical noise.

-The Duct's Diameter will be 6" or 15cm. Hence the Radius will be half that, 3" or 7.5cm.

-I will calculate the Duct's Circle Area with the following formula: Area= Pi x radius x radius. (Pi is a stable number; don't know the exact translation in English.. It's always the number 3.14)

-Area(in cm)= 3.14 x 7.5 x 7.5= 176.6 sq.cm Area(in inches)= 3.14 x 3 x 3 = 28 sq.inches

-Twice the surface of that is 353 sq.cm and 56 sq.inches

-If I want an entirely square silencer I just do the Square root of those numbers. Which is 18.8 cm and 7.2 inches.

-So for a square silencer, the inside size of the silencer pathway not including the thickness of the wood and the insulation will be 18.8 cm/7.2".

-So the perimeter of the area is 75.2cm / 28.8"

-If I want a rectangular shaped silencer, i.e. with the silencer's inner pathway height at 15cm / 6" then the width will be 22.5cm / 8.8".

-Also I will be applying the silencers directly on the drilled hole on the drywall for the best soundproofing. Sealed with caulk of course.

-The outlet of the supply silencer will be double the area-size of the ducts to reduce the air velocity in half, for a quieter air flow.
In this case the hole, can be 22.5 cm x 15 cm or 8.8" x 6". This way you still get the same volume of air, with less speed.

-I will probably be making 2 90degree corners. Although I've read that the more corners the better.

I've also attached a pic detailing better the dimensions of the rectangular silencer.
Please say what you think of this? This is what I understand so far on the subject of silencers.

Thank you,
Vakis

[vakis]

Is anybody even watching this thread...?

[TomVan]

Vakis,
Its a four day holiday weekend here!
But I needed to come into work today
Usually kill some time reading here during my work day

I think they look great but would add one more corner with a slight over lap maybe an inch or two.
Peace
Tom

[gullfo]

Looks good. Take into account the top and bottom need the insulation as well. Also, is the 6 in duct sufficient? Have you looked into the air velocity vs air volume to minimize velocity but have sufficient volume?

[vakis]

Hey Tom, sorry to hear that

I'll see if I can add another corner. This size is basically more or less the ideal size to fit flushed in my construction.
As long as the basic design is ok, I'm a bit relieved.

Glenn, I've got the height of the silencer on the illustration with the insulation added.

I'm confused with this Glenn sorry

Have you looked into the air velocity vs air volume to minimize velocity but have sufficient volume?

Thank you both for your replies,
Vakis

[britune]

Your cross sectional area is large enough to allow the air to flow and slow down to reduce noise. You have a good design.

The only idea I can think of to make it better would be to make the 36.8 inch length longer and add a third baffle. I made mine shorter, but later trashed them, and made them longer with one more turn... http://www.johnlsayers.com/phpBB2/viewt ... 6&start=30

But you have a nice design already. Good luck.

[vakis]

Hi, britune thanks for your input:)

I'm basically trying to fit the silencers into the already constructed framing. That's why I chose the 2 corners. Smaller size..
I'll see though if I can put them anywhere else so that I can do 3 corners, but it seems difficult.

This was a mistake on behalf of me. I thought that I wouldn't need a lot of ventilation..
I should have planned this before hand so as for it to be more aesthetically pleasing.
But anyways I keep learning and this forum is helping greatly at that.

The important thing now, is that It's going to be correctly done!

Cheers!
Vakis

[vakis]

I've been searching for sound proofing methods of the holes that are made from conventional split-unit air conditioners.
I did not find anything, so if you have anything in mind please leave a link.

I was thinking of making a variation of the ventilation silencers but for the thinner ducts of the Daikins split units which are about 3 inches. So I would be attaching these directly at the holes that are required for the AC ducts.

Is this necessary, or can I just seal that duct hole with lots of caulk? Also Because they are thin I can drill the hole on the outter shell a couple of meters(6 feet) further on, so that the holes aren't directly facing each other.

I've attached an illustration to better understand what I'm saying. Any thoughts on this?

Vakis

[vakis]

Ok, I've got one last question if you can kindly answer, and I'm off to build my Silencers!!

I'm going to use a silencer for each shell. One for the Brick outer construction & one for the Room in a room Drywall construction.
This is just to be as safe as possible in the sound proofing department. Because I will only use 2 corners in the silencers due to lack of space.

My question is:
In the inner drywall shell I will make the silencer's size twice as large as the diameter of the fan.
Is it necessary to do this for my outter shell (brick wall) silencers?

If this is done for the sole purpose of reducing the velocity of the air in the recording area then I see no reason for it to happen in the outter shell silencers? Can I keep the outter silencers in the original size of the fan's diameter?

Thank you,
Vakis

[lilith_envy]

Hey,
I fear the guys aren't watching your thread closely.
I don't think a silencer will work in the way you pictured above.
the silencer need to be the last thing the air passes through as it enterd the room.
If you have a silencer then 1-2inched of bare pipe thats 1-2inches that noise can enter.

"Most" people using mini splits just run it trough the wall and caulk the holes.

Hopefully someone with mor eexperience will pipe in

[gullfo]

i think the Daikin unit has a small fresh air feed so it could be considered a small duct. not sure about how much it would conduct sound or if the velocity of it could result in room noise. getting the fresh air in is one thing, getting stale air out is still needed. in most cases you use an ERV to maintain room temperature, or just a pair of air exchange units and let the split AC/heat pump unit to maintain a reasonable temp.

in this case, a split unit w/o the fresh air feature (decoupled and seal the coolant pipe entry) and a pair of silencer boxes (one with a fan, both with flow controls to prevent unwanted air exchange) to do the air exchange is probably about right but i'd suggest talking to a HVAC engineer who can assess the situation on the ground and make recommendations based on sensible and latent loads etc which could impact the fresh air exchange design. if you have Rod's book Home Recording Studio: Build It like The Pros, he goes into quite a bit of detail on this topic and has some spreadsheets which can help.

[vakis]

Lilith, the silencers for the split-units would also have caulk on those holes. (Maby a bit too much leafs..?)
Perhaps I could just make a simple silencer just for the inside that would have at least one 90 degree corner.
Caulked at the entry and exit points.

"Most" people using mini splits just run it trough the wall and caulk the holes.

I was thinking of this as well, but wanted to hear your opinions on the subject. It's a very possible solution for me though now,
from what you are suggesting.

Glenn,

i'd suggest talking to a HVAC engineer who can assess the situation on the ground and make recommendations based on sensible and latent loads etc which could impact the fresh air exchange design.

Sorry, I didn't understand this. Are you saying that the change of temperature made by the split-units, will also affect the fresh-air ventilation process?

I was thinking of installing an HRV in the future, but it's a bit difficult now, due to economical reasons.

Just as an overview.
-I will install a return and a supply air line for each room. (2 rooms-2 fans each room) As was suggested by an HVAC company.
-I will also install a split-unit for each room to handle the humidity and temperature.

Thank you both for your suggestions.