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What do you guys/gals think of PVC for FR enclosure?
What do you guys/gals think of PVC for FR enclosure?
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Old 1st November 2017, 10:05 PM   #31
Dr1v3n is offline Dr1v3n  United States
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Here's the new setup, no PVC wasted. N42 magnet holds it real nice.
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Old 2nd November 2017, 01:14 AM   #32
Zarathu is offline Zarathu  United States
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Quote:
Originally Posted by Dr1v3n View Post
Compared to my arrays, they sound less 'boomy' buts it's not a fair comparison yet as these aren't broken in.
Cheers
The physics of sound in closed tubes eliminates the creation of even order harmonics. Even ordered harmonics are the harmonics that cause boominess in the return of the sound through the cone again milliseconds later, 180 degrees out of phase.

The sound that returns is only odd ordered harmonics which in small amounts brings increased clarity and zero boominess.

Also the sound travels, not in all directions, but in a wave toward the back of the tube. If the rear is either lumpy or angled, then there are no standing waves, and the sound travels back again in a wave.

Fiberglass in the tube will convert the sound to heat.
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Old 2nd November 2017, 01:21 AM   #33
Zarathu is offline Zarathu  United States
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Quote:
Originally Posted by Dr1v3n View Post
Gears churning for 24 PVC enclosures, including newer more eye appealing attachment fixtures. No wasted PVC, except the dust.
I used 17 per channel--3.5 inch speakers, each 23 inches long, in my previous line array, using 4 inch thin walled PVC pipe. My current design requires 24 per channel using 2.5 inch speakers in 3 inch mailing tubes that are about 13 inches long, stuffed with 4 lb/cu ft fiberglass, with a lumpy back. Black rubber paint can be used to deaden the vibrations of the tube on the outside. The tube itself gets stronger the more sound energy is given to it.
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Old 2nd November 2017, 08:03 AM   #34
picowallspeaker is offline picowallspeaker  Italy
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Is that a Helmholtz resonator ?
Unfinished Shumann ?
Left place for a spot ?
Hit me with the ball ?
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Old 2nd November 2017, 08:10 AM   #35
picowallspeaker is offline picowallspeaker  Italy
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Quote:
Originally Posted by Zarathu View Post
4 inch thin walled PVC pipe.
1/4 "

Ah, memories ! I used 1/2" cardboard pipes with the foils you buy at the "car body" shops, which are one foil of bitumen composite and waste clothes material pressed ( some call it felt, which it isn't ), placed internally. Outside, PVC foil for aesthetics and reinforcement

Big and thick PVC pipes are indeed quite ( I'd say 50 in a scale to 100 ) sound transmission proof.
OOOOOOHHHH now I realize what's the FR in the title
Sorry for the rambling of the previous post
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Old 2nd November 2017, 10:22 AM   #36
Dr1v3n is offline Dr1v3n  United States
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All comments welcome, negative or positive!
I use .14" thick PVC for the pipe which joins the 2 endcaps. The endcaps are about 2x as thick where they meet. Even thicker, like 3/8" where I cut the hole for the P7. Then that becomes abit thinner after shaving the surface flat for the driver, closer to .14". I can take measurements if anyone cares at this stage.

Last edited by Dr1v3n; 2nd November 2017 at 10:31 AM.
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Old 2nd November 2017, 10:34 AM   #37
Dr1v3n is offline Dr1v3n  United States
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Quote:
Originally Posted by Zarathu View Post
The physics of sound in closed tubes eliminates the creation of even order harmonics. Even ordered harmonics are the harmonics that cause boominess in the return of the sound through the cone again milliseconds later, 180 degrees out of phase.

The sound that returns is only odd ordered harmonics which in small amounts brings increased clarity and zero boominess.

Also the sound travels, not in all directions, but in a wave toward the back of the tube. If the rear is either lumpy or angled, then there are no standing waves, and the sound travels back again in a wave.

Fiberglass in the tube will convert the sound to heat.
Now we're getting to the meat! I do plan on using fiberglass, the itchy stuff! And I don't hear any resonances so far with no filling even. They are cutoff at 150Hz. Even when I change to 100Hz cutoff, I don't hear anything objectionable.
They do have a different sound than the squares, that I can say for sure.

Ordered the rest of the magnets for 20 enclosures. All I have left is to sand down 20 endcaps to mount the P7's. 4 done already.
This will come out to 12 per side.

EDIT: They have a volume of about .11cuft or close to 3litres. I also got Krylon Fusion Gloss Black spray paint and Clear for the final touch.

Last edited by Dr1v3n; 2nd November 2017 at 10:36 AM.
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Old 3rd November 2017, 02:05 PM   #38
Vix is offline Vix  Yugoslavia
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Speaking of tube sound...(pun intended)
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Old 4th November 2017, 12:26 AM   #39
Dr1v3n is offline Dr1v3n  United States
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Quote:
Originally Posted by Zarathu View Post
The physics of sound in closed tubes eliminates the creation of even order harmonics. Even ordered harmonics are the harmonics that cause boominess in the return of the sound through the cone again milliseconds later, 180 degrees out of phase.

The sound that returns is only odd ordered harmonics which in small amounts brings increased clarity and zero boominess.

Also the sound travels, not in all directions, but in a wave toward the back of the tube. If the rear is either lumpy or angled, then there are no standing waves, and the sound travels back again in a wave.

Fiberglass in the tube will convert the sound to heat.
Zarathu, thx a mil for posting. A couple questions I have out of curiousity, since I'm experimenting out of my realm....

1) Would there be any value to mixing square enclosures amongst the tubes so one gets a mix of even and odd harmonics?
2) Why does the fiberglass heat up from the sound waves in your opinion? And at what SPL levels?
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Old 4th November 2017, 12:46 AM   #40
planet10 is offline planet10  Canada
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What do you guys/gals think of PVC for FR enclosure?
The fiberglass converts the sound energy into heat thus dissipating it.

As to a mix of even & odd harmonics i am leary.

dave
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