Odd port shapes/configs

[phreeky82]

I'm using winisd to calculate sub box stuff, and would like try and idea of using a port that slowly goes from a small opening (inside the box) to a larger opening on the outside.......so, tapered at a shallow angle to give minimal turbulence without needed a mega-long port.

It will be a slot style port, not round.

If it, say, starts out at 20mm high, and goes out to 40mm high at the exit, will it be the equivelant of a 30mm port all the way (assuming constant width)? In practice does this simple calculation work?

Any other "tricks" I should consider?

[bjorno]

phreeky82:

...so, tapered at a shallow angle to give minimal turbulence without needed a mega-long port….It will be a slot style port, not round...In practice does this simple calculation work?…

No it won’t, your assumptions need a better understanding of port slot profile acoustics. See at the links at:

http://www.diyaudio.com/forums/showt...62#post1054262

or:

http://www.lam.jussieu.fr/src/Membre...rin_polack.pdf

http://www.lam.jussieu.fr/src/Membre...inAES116th.pdf

I also rec. you to read the AKAbak manual at page 178 = ‘Duct’ considering the choice of port cross sectional areas.

A picture of successful implementation of slot profile ports (as in fig # 5 (AES 112th) page 3) in use (tuned to 40 Hz/ 9 Litres/driver box for 7 Seas P14 RCY in a horizontal row) can be found here:

http://www.diyaudio.com/forums/attac...amp=1177625327


b

1(1)

[phreeky82]

Cheers, some of that looks like interesting reading.

I wanted to put something together relatively quickly and reliably (i.e. i don't wanna experiment too much for this project), so I'll go with simple port for this box and maybe dive into that stuff for some test boxes in the future.