CurtPalme.com Home Theater Forum

Per 489 · Joined: 09 Jun 2007 Posts: 31 Location: Aaland. Finland

I´m thinking of building an hushbox and don´t want to hassle with external fans and pipes.

Has anyone tried an open hushbox? I´hm wondering if you could trap the sound but not the air?

Put a bigger box around the projector with enough air gap and put a soundtrapping material on inside wall.
Front more or less open and a plate at the back that folds over the box (like a tilted U).
How much space do you need between PJ and wall and how big openings at front and back?

I Have an M 8500 LC.

P.S
I´m going to New Zealand in Dec so if anyone there needs a board or two from Sweden I could probably take them with me. D.S

Per.

**kal** · Posted: Thu Jul 10, 2008 3:27 pm Post subject:

It's a bit of a catch-22. If you leave enough space so that the hushbox can vent without using fans/pipes, the sound is going to get out.

So no, an open hushbox doesn't really work without frying the projector.

Kal

dbaisey · Posted: Thu Jul 10, 2008 4:57 pm Post subject:

I have seen one made for the NEC XG. Its made out of 1/2" white laminated foam 2" larger then the projector. The top and front are open but gets its support by sliding it on from the back with top/side supports. Had him add a fan tunnel to the rear to vent upwards. Weighs about 8 lbs total and doesnt look that bad.

This was done because he sits just behind the projector and a low ceiling. It does stop most of the sound directed down.

dropzone7 · Joined: 12 Jun 2007 Posts: 1069 Location: Charlotte, NC

perisoft · Joined: 29 Aug 2007 Posts: 2920 Location: Ithaca, NY

I wonder if anybody's tried using water cooling / peltier junctions to cool CRT PJs. It would seem that some of the stuff used for ludicrous PC cooling should be applicable, although it would be quite different to implement - I'm guessing there aren't just a few heat-generating components that you need to cool off?

What bits in a CRT PJ are the ones that get hot and die, anyway?

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

When this has come up in the past, people generally get nervous about running water pipes anywhere near 40kV. Smile

Peltier junctions mostly cool flat surfaces, and that could help for STK chips (a popular get-hot-and-die component) & the like.

Mostly, though, you've got some honkin' big heaters in there, and they (CRT tubes) aren't very amenable to water cooling or junction cooling. You just need to pull all the hot air out. Hi tek cooling solutions don't help much with that.

Person99 · Joined: 09 Mar 2006 Posts: 4899 Location: Flower Mound, TX

stefuel · Posted: Thu Jul 10, 2008 9:55 pm Post subject:

If I were to start all over again and build a theater from scratch, I'd build a 100% sealed hush box from foam and optical glass. I'd run a 5 inch supply duct and 4 inch return duct right off my HVAC system to the inside of the box. I'd wire it so that whenever the PJ is on, the A/C fan would switch on. I'd let the house thermostat still decide if A/C is needed. That would provide filtered air to cool the PJ.

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

Curious -- why 5" in & 4" out?

stefuel · Posted: Thu Jul 10, 2008 10:43 pm Post subject:

Zebu Fellenz · Joined: 21 Dec 2006 Posts: 2567

dbaisey · Posted: Fri Jul 11, 2008 3:34 am Post subject:

Drop,
The whole case is designed to work together in air flow. Regardless you want a steady consistent temp maintained in the drive cavity. Having flow direction will help but have seen them with and without the sides. Might PM Kenny G I think hes done temp readings with the case removed but sealed in the HB. His is to quiet for me..its spooky quiet.

dropzone7 · Joined: 12 Jun 2007 Posts: 1069 Location: Charlotte, NC

Doug, "spooky quiet" would be great for me. Right now I'm somewhere between restroom hand dryer and Harrier jet. The heat is even worse. It doesn't help that this room is the warmest in the house for some reason and then add the XG heat pump and it can get uncomfortable in a hurry. A few nights ago I measured the ambient temperature in the room from the center seat below the projector at around 80 degrees. The rest of the house is about 73 most days. Even if it doesn't get any quieter, I have got to suck some of that hot air out of the room. I'm sure all that hot air pooling around the projector at the ceiling is not a good thing either.

dbaisey · Posted: Fri Jul 11, 2008 4:56 am Post subject:

Chip,
I think you would find a very unstable projector esp when the A/C kicked in on top of the fan, maybe even a cracked tube or three

mike calcott · Joined: 18 May 2006 Posts: 307 Location: Australia

The expansion with heat and contraction with A/C cooling would be dramatic causing cracked tubes as Doug mentioned

Per 489 · Joined: 09 Jun 2007 Posts: 31 Location: Aaland. Finland

Thanks for the replies.
I do understand that you can´t completely get rid of all sounds this way but by folding the box you could probably get rid of quite a lot.

I remember one time when i wisted a labyrinth made of peatbricks. It was about 2,5 m high and i must say it dampened most of the sound I made and most of the sound coming from the outside. A strange feeling indeed.

I´m going to measure temp and decibel before and after. Any specific places that I should consider when placing the tempprobe? Any "max" temp when I should bite the apple and pull the plug?

Per

stefuel · Posted: Fri Jul 11, 2008 9:56 am Post subject: