Stewart Stremler wrote:
Yes... and if that path is by way of the exhaust ducting, it's golden!
Still really noisy though. There are sound-resistant ducts which are
double-walled. I'd opt for one of those if I were doing this project.
That being said, I could design a (relatively) soundproof box
in which to put my computer (or other noisy equipment), but I doubt the
effort required in building the double-studded, triple-insulated
enclosure would really make up for the meager savings in noise.
That sounds like overkill.
That's how true soundproofing is done, though. In addition to the
doublewall construction, you also need two doors. Want to see inside?
Double-pane the interior door, and single-pane the exterior. It's those
buffers full of air that stop sound, not the solid surfaces. Sound is
transmitted more efficiently through solid surfaces than air. It's due
to resonance. The ideal design takes into account that resonance and
uses it against itself: design your enclosure to minimize vibration
while at the same time using inverse harmonic vibration to dampen those
vibrations. It's the concept used in dead rooms in recording studios.
You'll rarely find 90 degree angles that aren't in some way fitted with
traps. Since we don't care about resonance inside the box, just sound
escaping outside, 90 degree angles and parallel surfaces aren't really
that important a consideration. It's the leakage factor we're worried
about. So, we construct doublewall enclosures that only have a small
surface area in contact with one another. In between the walls, we line
two different densities of foam to deaden vibrations. The third
insulation is a cushion of air in between the foam pieces.
Granted, the structure I eluded to above is a bit overkill, but as I
tend to over-engineer things and make them solid as a brick shithouse,
that's not surprising.
I recall boxes to be used with line and daisy-wheel printers, and they
did a remarkable job in reducing the level of noise. (From "very
loud" to "a little noisy", mostly. Line printers aren't generally
all that quiet.)
Probably doublewall boxes insulated with foam. Much like flight case
construction, actually. Those do a decent job
IIRC, they mostly accomplished this with solid construction (nothing
to rattle), baffling (sound-absorbent foam?), and a sort of faceted
shape (no or few parallel surfaces), that I assume was to minimize
resonance.
Yup. About the most inefficient structure to resonate sound is an uneven
pentagon. That's a pentagon with no two sides and angles the same length
or arc. This is why voice booths are typically in the corners of
recording studios :) It's easy to make an uneven pentagon in a corner.
I'm not an audio geek, however, nor did I ever buy one for my own
use (or even consider it). Real information would be welcome!
I'm an audio geek!
If anyone wants details on how to build a soundproofed enclosure, let me
know and I'll draw up some prints.
It might be interesting to build a few different boxes an measure the
output. How close can you get to a "soundproof" box on the cheap?
For around $50 or so I can build a mostly soundproofed box in which you
could house a decent sized computer. It'll take most of an entire 4x8
sheet of 1/4" or 3/8" plywood, three 1x2s, a bottle of wood glue, a
drill, counterset, box of #6 screws, a half-sheet of #4 polyurethane
foam, and a half-sheet of #1 polyurethane foam ... two sets of cupboard
hinges, and a half-sheet of 3/16 plexiglas. Silicone sealant and an
epoxy paint would also help tremendously.
The only part that's difficult in this scenario is the venting duct. I'd
have to engineer baffles in the back wall to trap the sound. At the same
time, i'd be decreasing airflow. I'd also have to engineer some way for
air to get in -- much the same problem as before. Oh well, I'll put some
thought into it and draw up some plans.
Oh, add to the parts list one fluid bearing, medium-flow 120mm fan, some
filter foam, and a finger grille. I'll figure something out for the
front vents.
cheers.
-kelsey
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