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ABS Drain pipe for ports

Discussion in 'Archived Threads 2001-2004' started by Brandon B, Oct 24, 2001.

  1. Brandon B

    Brandon B Second Unit

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    I've come across a type of pipe for drain waste vents which is ABS inside and outside, with a layer in the wall (which is called "cellular core" by the mfr) which is a very hard foam. Its purpose is to negate the need to use iron drain pipes in walls to deaden the water running sound. It is very stiff and strong, but MUCH lighter than PVC, and since its whole reason for being is to be acoustically damped, it seems like it's a great choice for porting tube.
    Any experience or thoughts on this stuff?
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  2. Brandon B

    Brandon B Second Unit

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    OK, even though no one bothered to respond to this post, I am going to add some more info, as this stuff seems pretty neat.
    I found a piece at work and it was the exact size I needed for my speaker ports, so I wondered if anyone else had used it. Turns out after some research, it is PVC not ABS. I asseumed it was ABS because it was black and glossier than most PVC. It is evidently a standard plumbing industry product, denoted as type ASTM F-891. If you search for "dwv cellular core" or "ASTM F-891" you will turn up several links to it such as the one below. It seems to come in 1, 2, 3 and 4 inch nominal size. It is very very light, but strong and very dead acoustically. Seems ideal to me for ports, as it will save weight if you are building a sub with large or several ports. One downside would be the foam layer will make radiusing the ends of the pipe difficult or immpossible..
    http://www.genovaproducts.com/sch40.htm
    ASTM F-891
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  3. Bill Catherall

    Bill Catherall Screenwriter

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    I don't really see how it would be any better in a sub than just regular PVC pipe. It's built to reduce noise from water flowing through it. Those acoustic properties are different than the ones needed for a sub. In a sub you're basically creating a resonant chamber for sound waves of a particular frequency to resonate. That's different than sound propigation through the walls of the pipe. If it's cheaper than I don't see how it could hurt. But if it's more expensive, I don't see the benefit.
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    Bill [​IMG]
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  4. Brandon B

    Brandon B Second Unit

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    First, it's lighter. Even for a large sub with a large port, it would probably only save a pound or few, but that might matter to some people.
    Second, the fact that it does not transmit sound means it's more acoustically inert. Which IS desirrable for all the materials in the cabinent, port included. The resonance you are speaking of is supposed to occur in the air contained in the port, not in the port material itself.
    Agreed, if it's a lot more money, it's not worth it. But I doubt it is a lot more money, or no contractor would bother using it.
    Lastly, I wasn't proposing it only for subs.
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