Enclosure - PVC

[blagosaurous]

I've been reading up on all sorts of designs to start a speakerbuilding project on and I have just a couple questions on enclosures that have been nagging me that I hope someone can explain...

1. Why aren't more speaker designs using PVC as the enclosure? I saw this design http://www.partsexpress.com/projectshowcase/tubular/index.html and the guy has managed to use 7" woofers even.

Would there be any disadvantage of using PVC? My plan would be to build a small 2 way speaker. Probably utilizing a 5" woofer and a 1" tweeter... I don't intend on using any big woofers in this project.

2. Why aren't more speaker designs angled like Theil speakers? Is their sloping design just a marketing strategy or just too hard to incorporate?

 

[jaxvon]

I've been reading up on all sorts of designs to start a speakerbuilding project on and I have just a couple questions on enclosures that have been nagging me that I hope someone can explain...

1. Why aren't more speaker designs using PVC as the enclosure? I saw this design http://www.partsexpress.com/projectshowcase/tubular/index.html and the guy has managed to use 7" woofers even.

Would there be any disadvantage of using PVC? My plan would be to build a small 2 way speaker. Probably utilizing a 5" woofer and a 1" tweeter... I don't intend on using any big woofers in this project.

2. Why aren't more speaker designs angled like Theil speakers? Is their sloping design just a marketing strategy or just too hard to incorporate?

PVC would need quite a bit of damping to do well as a speaker enclosure. I don't honestly think you'd accomplish much, if anything, by going with such a design. If you could somehow make sloped designs like B&W Nautilus speakers, then yes, but honestly you're better off building a super heavy duty box.

 

[Swerd]

1. Why aren't more speaker designs using PVC as the enclosure? I saw this design http://www.partsexpress.com/projectshowcase/tubular/index.html and the guy has managed to use 7" woofers even.

Would there be any disadvantage of using PVC? My plan would be to build a small 2 way speaker. Probably utilizing a 5" woofer and a 1" tweeter... I don't intend on using any big woofers in this project.

As long as the PVC is a cylindrical pipe, like the design you showed, it should be fine. Even thin cylindrical walls are pretty strong.

Speaker enclosures need to have as little resonant vibration as possible. MDF, at least ¾" thick, is usually used in rectangular box enclosures because as a woodfiber/glue composite MDF has less resonance than solid or ply wood. If flat sheets of PVC were available they would make poor speaker boxes unless they were very thick or heavily crossbraced.

2. Why aren't more speaker designs angled like Theil speakers? Is their sloping design just a marketing strategy or just too hard to incorporate?

Yes, cabinets with sloped front are more difficult to make. But it is a design with a real function, not a marketing trick. Theil speakers have crossovers with 1st order slopes, that work best if the acoustic centers of the woofer and tweeter are vertically aligned with each other. Since tweeters are shallower than woofers, the cabinet slope puts the tweeter farther back relative to the woofer.

 

[billnchristy]

I would seriously try to damp the inside of the PVC with something very heavy.

Ever tap on the side of a PVC pipe and here that metallicy thwang? I wouldnt want my bass sounding like that!!

Im sure they can be made to sound good, you could use a cardboard box and sound good if you did it right.

 

[Tex-amp]

Cabinet resonance is a bad thing.