AVS Forum banner

Status
Not open for further replies.
1 - 13 of 13 Posts

·
Registered
Joined
·
149 Posts
Discussion Starter #1
Several folks here have used this glass for their D-ILA hushboxes. I'm building one for my HT300.


Anyway, on the Edmund website, the glass is specified as 3.3mm nominal thickness. My question is: Is it really than thin? How could it afford much of a sound barrier if so? Thanks for any info.


-Tom
 

·
Registered
Joined
·
1,515 Posts
Tom, I use the Edmund glass in my homemade LT150 hushbox and it the sound barrier is really quite effective.
 

·
Premium Member
Joined
·
318 Posts
I have a G-15 mounted behind the rear wall in my HT and I am using that same glass (I believe it's an 8x10 piece). It is THAT thin and is a great sound barrier. It also has no visible impact on the picture, which is outstanding on my 92" greyhawk.


Great product. Inexpensive and very effective for this application.


Alan
 

·
Registered
Joined
·
1,567 Posts
Hi Folks,

Do you have a part or SKU number for the specific glass you have had success with?

Thanks,

John G
 

·
Registered
Joined
·
1,567 Posts
Greg,

Thanks. Much appreciated.
 

·
Registered
Joined
·
7 Posts
Hi All,


I had the chance to look at the specs on the Edmunds site and for $38 for an 8x10 piece of float glass ( coated ) I think that you'd be better of going down to a local picture framer and getting them to cut you some glass.


I'm not too well informed on what hush boxes look like but I do know optical systems.


An uncoated float glass plate ( basically window glass ) you would expect to loose not more than 3% of the transmitted light ... and that's being extream.


I would suggest that you have a look at making your own from picture frame glass ( about the same thickness ) and if your unhappy with the out come get back to me as , if there is enough interest , I could look into getting the plates coated at my facility. I do think that you be happy with your first results though.


Taff
 

·
Registered
Joined
·
121 Posts
No. For uncoated window glass with light normally incident on it you lose 4% per surface. Since it is a plate of glass that you are going through there are two surfaces so you will lose a total of 8%. This figure will vary somewhat with wavelength (color) of the light and is very sensitive to the angle the light hits the glass. It only goes UP from the 8% figure as the angle gets farther from normal incidence. You will also get multiple reflections within the glass potentially leading to multiple images. Next time you look out a window look to see if you can also see your reflection.
 

·
Registered
Joined
·
1,567 Posts
Hi Paul,

Are you saying that the glass being recommended is NOT the way to go? What is the difference between the "Float Glass" and "Optical Glass"?

Thanks,

John G
 

·
Registered
Joined
·
121 Posts
What I am saying is that I believe that an anti-reflection coating on an optical window for your PJ is the way to go. While it is not as cheap as a plate of glass, at $20 to $40 it is a small fraction of the cost of your PJ and the performance difference (coated vs uncoated) will be worth the addded expense.
 

·
Registered
Joined
·
4,720 Posts
I have to agree wholeheartedly with Paul - the Edmund Scientific anti-reflective glass is definitely the way to go.

[ You can be sure all the glass in your PJ's optics system is AR coated - the manufacturer did that for a reason - and

you should continue the practice. ]


Not only do you not want the loss of light due to reflections - Taff, you definitely don't want to be sending

a few percent of your projector's output energy back into the projector through the front lens.


Although the cost may seem high - it's only of few tens of dollars - a trivial cost compared to the projector and the

other components of an A/V system.


This is not a good place to scrimp - you don't save much money - and the downside just plain isn't worth it.


Dr. Gregory Greenman

Physicist
 

·
Registered
Joined
·
735 Posts
I used an 8x10 picture frame to mount my edmunds. At first I didn't really see any difference between the original glass and the edmunds.

When mounted, looking straight at the lens and glass, I could not even tell there was any glass plate there due to the non perceptible reflections!!
 

·
Registered
Joined
·
199 Posts
I too used the glass in question (Edmund) in my hushbox design. The sound is not transmitted via the glass, nor the 1/4" lexan shell. I also agree with the AR argument. I used a 3"x3" in my design.


FWIW,

Jay
 
1 - 13 of 13 Posts
Status
Not open for further replies.
Top