What do you guys/gals think of PVC for FR enclosure?

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It's very nice the endcaps are rounded internally and externally. It's also nice that the PVC is thicker on the front where the driver is as opposed the thickness where the pipe comes in: 8.5mm vs. ~6.8mm. The P7 flange thickness is only about 3mm which leaves a 5.5mm mounting surface, plenty sturdy. Perfect and flush mounted too, more on that later...
I've also researched how to stain PVC vs painting which can flake. More on that too when the parts come in, but it involves methyl ethyl ketone and petroleum dye mix in order to penetrate the PVC without affecting dimensions.

Cheers
 
Rather than messing w/ methyl ethyl ketone (AKA: MEK), I would find some paint intended for plastics. MEK is wicked, nasty stuff. IIRC, there were folks in the printing industry who suffered permanet neurological damage from that stuff!

Just the opinion of a retired analytical chemist.

Cheers, Jim
 
Rather than messing w/ methyl ethyl ketone (AKA: MEK), I would find some paint intended for plastics. MEK is wicked, nasty stuff. IIRC, there were folks in the printing industry who suffered permanet neurological damage from that stuff!

Just the opinion of a retired analytical chemist.

Cheers, Jim
I read the wiki on Butanone/MEK. I don't want to endanger myself or my family with the lingering fumes after painting the tubes and endcaps with this stuff. So, I'm abandoning this process. I'll find another way to color coordinate the enclosures with the drivers.
Thanks very much for your post Jim!
 
Ok, I finally got the tubes in. Jeezus what a mess. Only got 13 out of 28...
 

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All parts here for 4 experimental units. Now how to tell if the holes for the drivers have been drilled 'true' center. I'll mount the drivers and literally just roll the endcaps and observe.
 

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Got 2 of the new ones wired up . I'll be listening to them for the next couple weeks to break them in.
I should've gotten 9" long tubes because both endcaps add about 3 inches to overall volume. Also, these 5" PVC tubes actually measure 5 3/8" ID (136.5mm) 5 9/16" OD (141.3mm) for .2cuft or 5.7litres.
With no stuffing/felt or internal damping they sound very good at low volumes... Will have to wait to try louder volumes. Compared to my arrays, they sound less 'boomy' buts it's not a fair comparison yet as these aren't broken in.
I'm currently wiring up the other 2 and trying to figure out a temporary and long term mounting solutions.

Cheers
 
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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.
 
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.
 
4 inch thin walled PVC pipe.
1/4 " :confused:

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 :eek:) sound transmission proof.
OOOOOOHHHH now I realize what's the FR in the title :p
Sorry for the rambling of the previous post :D
 
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.
 
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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.
 
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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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