rubber bucket as dog box ?

[pos]

Hello,

I was thinking of using a rubber bucket as a dog box for a 10" driver.
These buckets are quite heavy and thick, and also self-damped.
It would be easy to cut it to the proper depth, and glue it directly to the front baffle.

What do you think?

[Evets]

I applaud your creative thinking. Having never tried this I can only voice my concern that the ratio of weight (these are heavy buckets as you noted) to the surface area available for gluing will require a very strong epoxy to keep the glue joint from failing due to the weight. Perhaps a rebate or mounting ring to increase the surface area of the glue joint would be necessary. Also, if these are anything like the rubber buckets I used on the farm as a kid (and they look just like them) they could be susceptible to sagging and/or hardening over time which may reduce their damping ability; however, given the application the hardening aspect will probably be minimized. It sounds like a practice baffle - doghouse setup is in order. Good luck with your project.

-Steve

[hjames]

Somehow I think even a stiff rubber is going to flex" (breathe?) like a heart or a lung within that larger chamber under extreme sound pressure levels, and the 10" isn't your worry, its the 15" or 18" woofer.

The original 434x style Monitors used a MDF (particle board/wood product) dogbox that is not flexible or breathable in any fashion. The driver is sealed to the baffleboard (which acts as the front of the dogbox) so no pressure is exchanged with the larger chamber used by the woofer. The sides fit into dadoed groves on the back of the baffleboard and held with woodglue. Its a tight fit - braces go to the back panel to hold it tight.

View the inner perspective of Bo's 4345s here:

http://audioheritage.org/vbulletin/a...1&d=1156702245

[Baron030]

I am not so sure that a rubber bucket would work as a dog box. Not, because of the vibrations caused by the 10" driver housed inside. My concern is the vibrations caused by the woofer bleeding into the dog box from the outside. One option would be to reinforce the bucket with a lot of fiberglass & epoxy. But, that is going to be very expensive and messy to do. So, I would recommend looking into a really thick walled cardboard tube that is commonly used for concrete forms.
Link: www.sonotube.com
Sonotubes are inexpensive and are very rigid. Hell, I even have friends that use them for telescope tubing in their homemade Newtonians. So, I know first hand just how rigid this stuff really is.

Note: Concrete forms are usually covered with waxy waterproof film. So, you will need to sand this coating off in areas, where you plan on using glue, otherwise the glue won’t stick.

And that my $0.02,
Baron030

[Ian Mackenzie]

There are better options:

Why not use a cylinder cardboard form tube used for forming concrete pillars. They are very rigid and it is simple to router an mbf end cap and insert for the baffle

I used them for a project a little while back and it was excellent.

Ian

[pos]

Thank you all for your replies!

the ratio of weight (these are heavy buckets as you noted) to the surface area available for gluing will require a very strong epoxy to keep the glue joint from failing due to the weight.

Yes, I see. Some buckets have small overhangs to fix the handles. Maybe that could help with the glue.
Or maybe some sort of strap could be used if the bucket touch a side of the cabinet, as Weslake did in its early models to maintain the heavy 2" driver?

Somehow I think even a stiff rubber is going to flex" (breathe?) like a heart or a lung within that larger chamber under extreme sound pressure levels.

That make sense. That would specially be a problem if the woofer box was also sealed. This rubber is definitly flexible.

My concern is the vibrations caused by the woofer bleeding into the dog box from the outside. One option would be to reinforce the bucket with a lot of fiberglass & epoxy. But, that is going to be very expensive and messy to do. So, I would recommend looking into a really thick walled cardboard tube that is commonly used for concrete forms.

Why not use a cylinder cardboard form tube used for forming concrete pillars. They are very rigid and it is simple to router an mbf end cap and insert for the baffle

I used them for a project a little while back and it was excellent.

The sonotube option is sound, but also harder to install, with that rear panel that has to be glued and the necessary brace implied.
By the way Ian, I really like this idea of having sloped rear panel on your pictures!

The idea of the bucket was more a matter of laziness and inability with woodwork than anything else. I can see how to glue a little piece of rubber to a front baffle but anything more and I am lost !
Plus I want to insert this dog box in an existing box, the only existing opening being the 15" woofer hole.

But if you say that stiffness is paramount for a dog box then I will investigate with this sonotube idea.
Thank you Baron for the tips about the waterproof film, I am sure I would have fallen into that trap!

[macaroonie]

Bucket with Lansoplas ?

[toddalin]

Could use a 12" pvc cap..., maybe even a 10".

[Ian Mackenzie]

The sonotube option is sound, but also harder to install, with that rear panel that has to be glued and the necessary brace implied.
By the way Ian, I really like this idea of having sloped rear panel on your pictures!

Yes it worked very well.

When I get few few moments I plan to re design my 4345 enclosures along those lines with a removable upper front panel to try different HF components.

[boputnam]

The sonotube option is sound, but also harder to install, with that rear panel that has to be glued and the necessary brace implied. By the way Ian, I really like this idea of having sloped rear panel...

Actually, the sonotube is not "harder to install" than your bucket idea - it glues to the baffle just fine. I have done many this way, and they are all very sound. Sonotube is very solid material, that will not shrink nor dry out.

Once you poke the wires through, just caulk the hole tight.

The angled rear / cap to the sonotube was recommended long-ago by Giskard, who encouraged avoiding flat reflection surfaces whenever possible.

[Baron030]

There is one more tip that I can suggest.
Use router to cut about circular slot about a 1/2" (12mm) deep on the front and rear panels for the tubing to slip into. This will form a much stronger dado joint between the tubing and the wood panels. This refinement will be real easy to do on the front panel with a circle cutting jig. Admittedly, cutting a slot in the rear panel will be trickier to do, because you have to cut an elliptical slot in the tilted rear panel. But, I don’t see it as being impossible to do free hand, just fill in any gaps in the joint with lots of epoxy.

And here is link to some suggested reading:
http://www.audioheritage.org/html/pe...s/2-horns.html

Baron030

[Ian Mackenzie]

Actually, the sonotube is not "harder to install" than your bucket idea - it glues to the baffle just fine. I have done many this way, and they are all very sound. Sonotube is very solid material, that will not shrink nor dry out.

Once you poke the wires through, just caulk the hole tight.

The angled rear / cap to the sonotube was recommended long-ago by Giskard, who encouraged avoiding flat reflection surfaces whenever possible.

Bo,

Its an old idea but a good one as discussed in numerous loudspeaker building text. I worked out the volume using Bassbox enclosure guides and that is where I got the idea initally as there is a guide for this style of sub chamber in there.

This particular project was dated early 1998.....well before the forums.

The baffle was laminated 3/4 inch MDF with the front layer forming the driver cut out (initially Audax HT210 TO) and I cut rear layer to form a lip for gluing the sonotube. (about 10 inches in diameter)

The front to rear braces made it convenient to provide further support for the rear baffle.

Ian

[boputnam]

This particular project was dated early 1998.....well before the forums.

So was Giskard...

In any case, good advice worthy of emphasizing.

[Ian Mackenzie]

If anyone goes the Sonotube route please let us know how it turns out.

Bo,

I think they make an Oval version.

Thought that might interest you!

[boputnam]

I think they make an Oval version.