Soundproofing DC Closet Inlet Tubes

[Michael Causey]

Hello,

I've a question I have not found an answer or suggestion to. I've purchased a Grizzly 0548Z 2HP DC. Even though I've researched it, it's still quite loud. And, I live in a townhouse with a 2-car garage. I wish to be considerate of the neighbors, plus I'm worried about the . . . let me put it politely . . . rather "active" HOA. I'm building a closet to contain the noise. I think I've got a good plan, except for the 3 inlet tubes, which initially I'm thinking will be cut at the bottom of the closet near the motor. Of course, I'll cut them in the back of the closet to point them away from the garage door opening, but if it's near the bottom, it'll be near the motor.

Do I just wrap the tubing proximal to the closet with foam and/or mass loaded vinyl? Do you think I should build a second acoustic baffle box with foam and some turns?

I would hate to build this thing and have the sound just escape through these three 4 inch+ holes.

Thanks for any help.

[jeth chiapas]

Hi Micheal. Untreated those pipes are going to cancel out a good part of the sound isolation capacity of your closet.
In diy studio builds it is common to run cables between isolated spaces through pvc ducting (heavyweight black sanitary pipe) that have their internal surfaces lined with an absorbant material and a 90 degree elbow at each end. I've seen heavy duty felt carpet underlay used for this in place of more expensive acoustic products such as high density mineral wool.
An MDF baffle box would also work with a similar massive and absorbant material lining and a good few turns.

[Dan Hintz]

The majority of your airflow-based noise is going to come from the turbulent output. The input airflow is going to be relatively laminar after traveling 5-10 feet from the tool. Spend your time on the output before worrying about the input side.

[Chris Parks]

Definitely the exhaust if it has a decent velocity. Let me put it this way, if the exhaust is not a problem you need to find a unit where it is because unless it is the air flow speed is too low.

[Ben Hatcher]

You may want to consider running a single, large diameter pipe outside of your enclosure and then wye off from there instead of running 3 lines out.

[jeth chiapas]

Airflow based noise is hard to "soundproof" as by necessity the inlets and outlets will be open to the area outside the isolated space. Lining the pipes as I mentioned should help reduce it. The isolated chamber itself basically serves to contain the noise of the motor itself and a hole just 1% of the area of an isolating structure can reduce its efficiency by around 10% so 3 large holes will make a huge difference to its effectiveness.
In studios all fittings are surface mount to avoid undermining the isolating structure and any required air paths (aircon, cable runs etc) are kept as long as possible, with turns and absorbant lining to minimise transmission of sound energy fromone space to another.

[mreza Salav]

I recently built a closet for my Clearvue (in the basement of our house), see the following:
http://www.sawmillcreek.org/showthread.php?172787-Setting-up-a-Clearvue

The exhaust is from the top (past the motor) to help cool it down too. It works VERY WELL to the extend that my wife says she doesn't notice
when I turn it on if she is on the second floor. Even inside the shop you can have a normal conversation when the thing is running.
I've used 3" thick Roxul bats and covered it with a thick cloth.