[burnin240sx]

Ok,
So I've built my speakers up until the front panel needs to be attached. So now I'm putting in the BH5 and wiring it up. But I'm a little confused about the diagram plans.

In this picture is shows strips of BH5 about 2 inches wide on the sides of the back speaker in yellow. I would have though that I should fill the entire back with bh5. I've colored in the spots with red to show what I am trying to say.



On the side here in blue can i use 1/2 inch foam?


What are the ramifications of using BH5 on all the back and/or is the back supposed to be filled in that way?

[Danny Richie]

If you look at the side view then you will see that the back wall is covered with BH-5 (or better still, No Rez).

The areas in Blue show where you need to include solid blocks of fiberglass insolation or polyfill.

I think what you might not be understanding is that these views are cut-away views.

[burnin240sx]

That's where I was confused. I was seeing the side view and thinking that it could be accurate because the back view only has about 2" wide strips. So I should fill the back side with BH5. So i could just go off of the side view only and completely fill the yellow areas.

what about using the 1" foam where the blue diagram shows. Is it that big of a issue to use the foam I got? Should I not use it and get fiberglass isolation(the stuff at lowes for home insulation?) or polyfill? I'm just curious as to the ramifications of using the foam instead of polyfill

[Danny Richie]

So I should fill the back side with BH5.

As per the plans, the whole back side is lined with BH5 (or No Rez as per the latest version of the plans).

So i could just go off of the side view only and completely fill the yellow areas.

The Yellow areas represent the BH5 (or No Rez).

what about using the 1" foam where the blue diagram shows. Is it that big of a issue to use the foam I got?

1" foam will not fill those areas (3 dimensionally those areas are larger than that) and if you did fill those areas with foam then it would inhibit are flow in the box. The Blue area represent areas that must be filled with fiberglass insolation of polyfill.

Should I not use it and get fiberglass isolation(the stuff at lowes for home insulation?) or polyfill? I'm just curious as to the ramifications of using the foam instead of polyfill

If you follow the plans, then it will work great.

[Ron]

 Danny is correct that the back wall does need to be covered with BH5 or No-Rez. I used No-Rez when I built my AV-3's and it works great. Also, I used Acousti-Stuf in lieu of fiberglass or poly-fil. In my opinion the Acousti-Stuf does a better job acoustically that either fiberglass or poly-fil. Midrange seems to be clearer and smoother. Also, the bass seems tighter and a little deeper. If you use Acousti-Stuf, I suggest that you lightly fill the back half of the enclosure directly behind the drivers. Also, when you install the BH5 or No-Rez you need to keep it back about 1-1/2 inches from behind the front baffle board.

[burnin240sx]

like this?


BTW thanks for all the help.

[Danny Richie]

Yes, and down the sides until you reach the top brace that makes up the transmission line.

[corndog71]

Did you cut that or is that a flat pack?

[burnin240sx]

Danny,
I think I understand where to put the BH5 now. Thanks again. The blue area is in between the BH5 and it's just poly fill material. not poly fill glued to the wall. I see said the blind speaker builder.

Corndog71,
I bought this stuff and had to cut it with a new razor.
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=260-535

I was confused as to what a flat pack was. I cut all the wood myself.

[Danny Richie]

Corndog71,
I bought this stuff and had to cut it with a new razor.
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=260-535

I hate to tell you, but that stuff will do more harm that good.

It has no damping layer, so there is nothing on it to control the resonances of the box. Each panel will resonant just as if there is nothing at all on it.

Then that suspended barrier that is in the middle of it will act as a passive radiator and do a little mass loading to the driver. But not in a good way like a typical passive radiator that is tuned to a low range. It tends to muddy up the mid-range.

The BH-5 can have that effect as well, but it also has a heavy (not as heavy as No Rez) damper to control resonances. So its good typically outweighs the bad.

I'd actually advise that you pull all of that stuff out of there.

If you want good effect on the cheap then go to Lowe's or Home Depot and by some heavy industrial floor tiles and glue it to the walls with contact cement.

Then go to a fabric store and get some open cell foam. Or peal the barrier layer off of that junk from PE and us it. Then use contact cement again to glue the 1" thick foam to the floor tiles that you glued in.

It is not as effective as lining it with No Rez, and you go have to breath a little contact cement, and put a little time into it, but it is a low cost solution that has good positive benefit.

That stuff from PE is design for noise control but putting it on a wall of a room or building. It will just to block noise from going from one side to another. Unfortunately, in a speaker enclosure, the walls are resonated by the pressure created in the box. So this stuff has little effect in a speaker application.

[Ron]

 I have used BH5, convoluted acoustical foam, and other types of sound damping in the past, but No-Rez is by far the best and most effective. It is moderately expensive, but well worth the extra cost. It definately does make an audible improvement in damping out unwanted cabinet resonance. I highly recommend this product.

[johnzm]

I hate to tell you, but that stuff will do more harm that good.

It has no damping layer, so there is nothing on it to control the resonances of the box. Each panel will resonant just as if there is nothing at all on it.

Then that suspended barrier that is in the middle of it will act as a passive radiator and do a little mass loading to the driver. But not in a good way like a typical passive radiator that is tuned to a low range. It tends to muddy up the mid-range.

The BH-5 can have that effect as well, but it also has a heavy (not as heavy as No Rez) damper to control resonances. So its good typically outweighs the bad.

I'd actually advise that you pull all of that stuff out of there.

If you want good effect on the cheap then go to Lowe's or Home Depot and by some heavy industrial floor tiles and glue it to the walls with contact cement.

Then go to a fabric store and get some open cell foam. Or peal the barrier layer off of that junk from PE and us it. Then use contact cement again to glue the 1" thick foam to the floor tiles that you glued in.

It is not as effective as lining it with No Rez, and you go have to breath a little contact cement, and put a little time into it, but it is a low cost solution that has good positive benefit.

That stuff from PE is design for noise control but putting it on a wall of a room or building. It will just to block noise from going from one side to another. Unfortunately, in a speaker enclosure, the walls are resonated by the pressure created in the box. So this stuff has little effect in a speaker application.

Danny,

I dont want to question your knowledge on how these things help, but moreso on the parts express product. mostly because i used a hell of alot of it in a couple pairs of speakers, and now you have me thinking.

have you ever handled a sheet of the parts express stuff? in the pictures it looks EXACTLY like blackhole5 where there is a foam base that adheres to the wall, a heavy asphalt type layer, and then a thick foam layer. i would have thought that the parts express sheets have a damping layer because each sheet weighs 5 lbs. but if the damping layer has to be directly attached to the wood for the to dampen, would blackhole 5 also suffer the same issues as the parts express foam? or there something else im miissing altogether about the parts express stuff?

Thanks for any replies, im just trying to gain some sanity here:)

[Danny Richie]

have you ever handled a sheet of the parts express stuff?

You bet. I think I still have some of it around here someplace.

in the pictures it looks EXACTLY like blackhole5 where there is a foam base that adheres to the wall, a heavy asphalt type layer, and then a thick foam layer. i would have thought that the parts express sheets have a damping layer because each sheet weighs 5 lbs.

Nope, BH-5 doesn't have a foam base that adheres to the wall. It has a 40 mil thick composite damping layer that adheres to the wall. The PE stuff has none. And a sheet of BH-5 weighs 8 lbs.

but if the damping layer has to be directly attached to the wood for the to dampen, would blackhole 5 also suffer the same issues as the parts express foam? or there something else im miissing altogether about the parts express stuff?

The BH-5 can have a negative effect in the mid-range in some applications because of the barrier layer (just like the PE foam).

My web site will explain it better:

http://www.gr-research.com/index.asp?PageAction=VIEWPROD&ProdID=103

[johnzm]

thanks for the reply danny,

now i get to sit here and sulk about how many speakers ive put the PE stuff in

maybe next time ill ask in a forum before impulse buying.
for future reference, would dynamat work if i were to make up my own stuff from scratch?

[jtwrace]

Danny

Does one have to worry about taking up volume in the encloure by using No-Rez?  Also, do you offer a discount with multiple sheets purchased?

Thanks

[Danny Richie]

would dynamat work if i were to make up my own stuff from scratch?

Dynamat makes a good first layer.

Does one have to worry about taking up volume in the encloure by using No-Rez?

Damping layers take up air space, but foam layers slow down the flow of air in the box and make the woofer act as if it is in a larger box. So it is usually a wash. It could add air space in some applications though, but not much.

Also, do you offer a discount with multiple sheets purchased?

Sure, there are price breaks at 10, 50, and 100 sheets.

[jtwrace]

 

[burnin240sx]

Well, I'm glad I didn't stick that stuff to the box yet. How big are the no-Rez sheets?

I'm assuming i'll need 2 of them for both speakers.

Oh, and I cut all the pieces myself.

If anyone is interested here is a gallery of my project.
http://www.dropbox.com/gallery/1250374/1/AV3?h=b703f4

[Danny Richie]

No Rez comes in 24" by 27" sheets.

[Danny Richie]

Wow, I just looked at the cheapy Sonic Barrier stuff at PE. That stuff comes in 18" by 24" sheets. So each sheet is 3 sq. ft. At $24.93 a sheet it is $8.31 a sq. ft.

No Rez comes in 24" by 27" sheets. That's 4.5 sq. ft. So at $38 a sheet, it is only $8.44 a sq. ft.

It's almost the exact same price! And I thought people were drawn to that stuff because it was cheaper.