I am building a vented sub box. I purchased some port tubes from
madisound.com. These are engineered tube with large flares at the
entrance and exit of the tube to allow for smooth air flow. What I
need to know is do I need to take into account the added volume these
flared ends are adding when figuring up the port tube length. The spec
sheet for the subs I'm using say to use 2in diam and 6.75in long tubes.
Should I do the math and shorten the overall tube length because of
the flared ends.

wrote:
I am building a vented sub box. I purchased some port tubes from
madisound.com. These are engineered tube with large flares at the
entrance and exit of the tube to allow for smooth air flow. What I
need to know is do I need to take into account the added volume these
flared ends are adding when figuring up the port tube length. The spec
sheet for the subs I'm using say to use 2in diam and 6.75in long tubes.
Should I do the math and shorten the overall tube length because of
the flared ends.


I wouldn't worry about it; the difference is likely too small to be
significant.


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There is actually quite a significant addition in volume, these tubes
have decent sized flares. here is a link with a pic so you can see
what i'm talking about

http://www.madisound.com/cgi-bin/ind....2920&pid=1585

understand that the tube is only 2in in diameter and then look at how
large the ends are in comparison. It's this difference that worries
me. Since this is the first sub box i have ever built, i don't want to
half-ass it and have it sound like crap.

wrote:
There is actually quite a significant addition in volume, these tubes
have decent sized flares. here is a link with a pic so you can see
what i'm talking about

http://www.madisound.com/cgi-bin/ind....2920&pid=1585

understand that the tube is only 2in in diameter and then look at how
large the ends are in comparison.

Yes, but the plastic itself is not taking up that much volume. Really,
it's not worth losing sleep over... if it were, I'd think the specs for
the tube would list how much extra volume it takes.



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The flared part of the tube is really not part of the volume of air that
makes up the port. It is there ONLY to reduce port-noise caused by
turbulence. Think about it, at the point the tube starts to flair you no
longer have restricted air-space. That part of the tube is doing virtually
nothing sound-wise. I agree with Matt, don't worry about it.

MOSFET

wrote in message
oups.com...
I am building a vented sub box. I purchased some port tubes from
madisound.com. These are engineered tube with large flares at the
entrance and exit of the tube to allow for smooth air flow. What I
need to know is do I need to take into account the added volume these
flared ends are adding when figuring up the port tube length. The spec
sheet for the subs I'm using say to use 2in diam and 6.75in long tubes.
Should I do the math and shorten the overall tube length because of
the flared ends.

What you say does make sense MOSFET. I appreciate both your guys help.