Critique this Baffle Box Design

[econnnn]

Materials:
- Duct tape
- A large shipping box
- An old sleeping bag

Procedure:
Sketchily duct tape an old sleeping bag around a cardboard box.

Finished product:
http://i.imgur.com/5xOLzgL.jpg
http://i.imgur.com/3fP9wRH.jpg

Testing:
The box reduces a 65 dB sound to 58 dB. The test was done using an iPhone sound measuring app and a youtube video of a generator. YMMV.

Playa modifications:
Lash it down to something. Cut an exhaust hole in the back.

Odds this overheats my generator while providing no sound reduction? Likely, or very likely?

[maladroit]

Shut the forum down for the year, this was the cherry on top. Funny as fuck!

[GreyCoyote]

You just earned your playa name.

Fireball.

[Canoe]

How about Flaming Tumble-Weed.

[skippy3k]

Damn it. It's the classic BM conundrum....I can't tell if he's being serious or it's a joke.

Reminds me of last year when I saw a family of four walking through Center Camp. They were all dressed in polo shirts and well pressed madras-style shorts and pushing a stroller with a small child in it. I couldn't tell if they were birgins and completely out of their element or part of a wonderful, "coming full circle" artistic expression. It's still troubled me to this day.

[Captain Goddammit]

I find that baffle box beyond criticism.

[HurtYurt]

The test was done using an iPhone sound measuring app and a youtube video of a generator

harr, harr, harr,
LMAO

[econnnn]

Haha, yea this is a joke. I was looking at building a baffle box and these were the materials I had on hand so the thought crossed my mind for about 5 seconds. Then I thought it was funny so decided to make a post.

[Token]

Stick tap for culture jamming.

This Cat gets it.

[Canoe]

... Reminds me of last year when I saw a family of four walking through Center Camp. They were all dressed in polo shirts and well pressed madras-style shorts and pushing a stroller with a small child in it...

[Zephyr40k]

Hi guys. I've been building a generator quiet box for the Playa and I've gotten around to testing it out. It does have vents, baffles, fan input and exhaust hole, and it does knock the sond down appreciably, but I am a bit worried about the heat.

I have a BBQ thermometer in there and within 20 minutes it gets uo t0 over 200 degrees farenheit inside the box. This is with the fan on. Is there a maximum safe temperature you folks would recommend? I suppose I could get a bigger fan and open the hole to fit it in, but would prefer not to modify it at this late date.


EDIT: OK yes I know this thread is a joke. But I am serious. And I didn't want to necro an older legit generator thread.

[The Rod]

Take the roof off. Make sure vent holes are cut towards the bottom end of the sides.

The best baffles direct the noise up.

Edit: Great thread.

[Canoe]

That design is great for stopping the box from transmitting/radiating the noise that it has absorbed from the generator. However, a two-pronged approach is more effective. You need a soft sound absorptive material treatment on the inside surface too, to damp the sound input to the cardboard surface. As you've already got it sized for your generator, you may not have sufficient room to add such material. I've heard that cardboard wet down with naphtha will become slightly pliable, hence sound absorptive/damping, yet without losing the bulk of its structural strength. YRMV

[Zephyr40k]

Cardboard wet down with naptha?

Erm... thanks but no thanks. Sounds a wee bit risky.

I do have the inside of the box lined with this stuff:

http://www.homedepot.com/p/Roxul-Safe-n ... ogId=10053

Which seems to be doing a good job of dampening the sound.

After much testing and much frustration I ripped out all the baffles. Now with the fans blowing directly on to the generator it maxes out at 148 degrees F and seems to be stable there. Only problem is the sound is much higher, especially on the back wall where the fans are. But I guess that's better than spontaneous combustion.

[Canoe]

Hmmm
Sounds like you might be serious.

If you want a serious easy design:
- thin plywood box. Twice the height of the generator. Number of sides doesn't matter. Preconstructed as a box, or transported as separate panels. They should join in a way that doesn't allow an air gap between the panel joints. Cardboard will fall apart if it rains, otherwise, o.k. unless there's a really strong blow.
- open top
- line both sides of the plywood with old carpet - can get wet, but it drains and dries quick enough
- use rubber cement or contact cement for better performance, but not essential
- glue/stable old underlay (if it's not falling apart into MOOP) onto the plywood first - great at damping both sound waves and the modulated plywood

The bulk of the noise is channelled upwards out of the box, away from people. Carpet (and rubber cement, underlay) on the inside of the box damps the sound waves as they reach the plywood; this minimizes how much the sound waves modulate the plywood into vibration. That vibration is transferred through the plywood to the outside. The carpet on the outside of the box inhibits the modulated plywood from radiating as sound. Underlay aids well to dampen vibration, but the carpet is essential to performance. The box is open at the top to air, so if there's enough room between the generator and the carpet/box, the airflow should be sufficient to keep the geni within its operating temps.

Super Version
Sound insulation has it's place, if you want to build a double walled box. Or, actually, two boxes, one that fits inside the other, with an air gap between them large enough for two layers of the sound insulation and a one inch air gap. Underlay on both sides of all plywood. Carpet on the outside of the outer box and the inside of the inner box. A layer of sound insulation goes on the inside of the outer box, and on the outside of the inner box, leaving a one inch air gap between the two boxes. Leave the bottom of the wall open (no wood plate/base); seal the exposed insulation with the sprayfoam flexible version that is used for sealing around windows, or with Stop-Leak spray. This is only really needed if the playa gets wet. You need a plywood top to cover the two box tops, cut out in the middle for the generator space. Treat both sides of that top with underlay.