Okay, so I'm building some silence cases...

[TheRealWaldo]

And I need some suggestions/recommendations on the best sound absorber/proofing to use internally. Current the design has a suspended frame inside a sealed plywood (1") case, looking for a treatment to go inside that dead-air space. We'd like at LEAST a 24dB broadband drop with the whole box.

The best STC for the price is where I'm going with this.

I've looked at acoutstic vinyl barrier (also known as mass loaded vinyl barrier), foams, etc. but all I've got is salesmans specs, no real world examples/opinions.

Shout!

W.

[Innovations]

Well, the mass loaded vinyl is not bad if measured by a density standpoint but the cheapest mass per pound of sheathing materials is gypsum board. Getting STC 24 out of a single leaf is going to be hard. You will have to pay close attention to the flanking paths.

[laptoppop]

Does it have to be mobile? A box made out of 6" thick concrete would isolate an amp pretty darn good.... <grin>

-lee-

[knightfly]

IF it's an amp you're trying to quiet, you might wanna look at this suggestion -

http://www.homerecording.com/bbs/sho...d.php?t=127850

[TheRealWaldo]

Nah, 'tis actually a PC case, so it needs airflow, etc.. I just need some batting basically to absorb some of the bounces within before they head out the air ports, and wondering who's got real world experience with some material to suggest some.

W.

[laptoppop]

I built the worlds ugliest computer isolation desk - but it works quite well. I used 1" thick 703 insulation wrapped in muslin fabric. Here are some pictures:
http://www.gracesongmusic.com/studio_c_4.htm

I don't have any plans -- I just used 3/4" plywood and 2x2 lumber and screws and matched the size of the 19" rack on the other side of the desk.

I used three fans on each side to move air through the sound baffles into/out of the main area.

-lee-

[TheRealWaldo]

What'd you use to power the fans?

W.

[laptoppop]

I'm using 12 volt fans, and provide power for the fans from the computer. I started off using 110 volt fans, but the ones I got were too noisy. I ended up with 12 volt enermax fans. I have three pushing air into the center area, and three pulling air out. The computer runs a few degrees hotter than if it is out in the open, but still well within reason.

-lee-

[Innovations]

Originally Posted by TheRealWaldo

Nah, 'tis actually a PC case, so it needs airflow, etc.. I just need some batting basically to absorb some of the bounces within before they head out the air ports, and wondering who's got real world experience with some material to suggest some.

W.

Well, if it is a Pc that you need to keep quiet then make step1 is making a quieter PC. Have you tried lower noise fans and variable speed power supplies? Or you can get really ambitious and go with water cooling. The combination of water cooling and a variable speed quiet power supply might negate the need for the case altogether. I have also seen small mufflers that just go over the back of the case.

Zalman even manufactures a very expensive computer case that is completely noiseless...no CPU fan, no Video card fan, no power supply fan, even a cooler/sound absorber for the hard disk.

Anyway since you dont really care if it is a great sonic environment inside the case you just want a heavy tightly sealed case with no flanking path other than the two ductways. These you make the airflow and noise path pass by a few turns and make lots of contact with 703 type stuff Put the fans on the inside so the fan noise has to take the same path too.

[IraqiFreedom]

You could try a cheap plastic pc case rather than the common aluminum ones. I have a lot of experience with PCs and I can say that the plastic cases are pretty quiet stock.

[crankz1]

An aluminum case would be the best type to have as it will dissipate heat faster and better than anything else, thus requiring less in terms of case fans.
laptoppop's box is a good method.

[IraqiFreedom]

More important then # of fans, is the fans themselves and minimizing vibrations from the fans, disks and ps. Installing *quiet fans* and damping everything inside is cheap and easy.

You can get really inexpensive and effective items here:

http://www.directron.com/iso80mm.html

[crankz1]

No ..... I didn't mean for him to get a laptop ......
I meant the member laptoppop's enclosure for his PC.
Check out the link he posted.

-Edit- Ok I see you have edited your post ..... Nevermind.

[TheRealWaldo]

All other options have been fully investigated, and some have been done as well, such as several modifications to the PCs themselves to make them super quiet. The lack of space is the biggest issue here, so the proximity of the PC to the microphone during recording is low, thus I need the silence case to shave off a few more dB.

Looks like I'll be going with the 703.

W.