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Design of Rectangular ports for a BassReflex Box |
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Steve_B 
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Joined: 29 September 2007 Status: Offline Points: 1587 |
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 Topic: Design of Rectangular ports for a BassReflex BoxPosted: 06 April 2011 at 6:23pm |
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While I am here, and because this is a thread on rectangular ports, if you didn't know, clicking on the shape changes the port to rectangular.
 edit - Subbass I hadn't seen your reply when I posted, so this is a general comment not aimed at you.
 Edited by Steve_B - 06 April 2011 at 6:26pm |
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subbass
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Joined: 30 March 2009 Location: bristol Status: Offline Points: 1683 |
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Posted: 06 April 2011 at 6:19pm |
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I stand 'corrected'
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Steve_B
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Posted: 06 April 2011 at 6:15pm |
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subbass
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Posted: 06 April 2011 at 6:02pm |
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remember that port lengths change depending on whether the port is flush or freeair - something that WinISD doesnt take into account...
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kevin tyler
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Posted: 06 April 2011 at 4:45pm |
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i was told turbosound or was it martin are shying away from the triangle ports, is this so?
kev  Edited by kevin tyler - 06 April 2011 at 4:49pm |
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DJ_habyb
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Posted: 05 April 2011 at 8:24am |
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If you know how to calculate the cilidrical port you will know how to calculete a triangle or a squer one.If you know the volum of the round port just make a triangle port with the same volume and you will have the same air volume passing tru and the same air speed.
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We kill the noise :P http://www.youtube.com/watch?v=triRKoBEcik
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endre_k
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Posted: 02 April 2011 at 8:40pm |
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June is age away.... but i have to work, exams, live, party, etc =)
by the way, the solution that i said in the SET UP DIAGRAM is it correct? thx again a lot :=) |
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Steve_B
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Posted: 02 April 2011 at 8:33pm |
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June is ages
away. I tend to
follow threads that I have contributed to and was puzzled when I couldn’t see
any of my posts in one of the other threads thinking it was this one. As I said
I’m not as young and sharp as I once was. If you wire
two drive units in parallel in one cabinet double the volume that you would use
for a single drive unit and then tune the port to the same frequency as you
would for a single drive unit. In the formula that you posted, the value of Vb doubles
and Fb stays the same. The other variables can be what you want. If you alter
the diameter (area) of the port, that will affect the length. |
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endre_k
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Posted: 02 April 2011 at 7:46pm |
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i found this if someone is interested, or can verify it is correct :
================================================ If "a" is the number of elements that are connected in series, electrically, "b" is 1 for normal configuration, 2 for isobaric configuration and "n" is the total number of elements, the new values are calculated as: Vas=Vas1*n/b^2 Bl=Bl1*a Sd=Sd1*n/b Re=Re1*a^2/n Le=Le1*a^2/n So two drivers in series, side by side has a=2, b=1, n=2 and Vas=2*Vas1 Bl=2*Bl1 Sd=2*Sd1 Re=2*Re1 Le=2*Le1 ==================================== |
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endre_k
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Posted: 02 April 2011 at 5:57pm |
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just one silly question, if i do something like this, but changing the 10Ohm R for a 4 Ohm R (because the 2 drivers in paralel equal to 4Ohms), and after, calculating the T/S parameters with the two drivers wired in paralel, will i be able to know how the T/S parameters change? and then be able to calculate the box with those values?
Could it be possible? Any considerations to do it? Or i'm just dreaming too much? Thanks again for all 
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endre_k
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Posted: 02 April 2011 at 5:37pm |
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Steve_B, sorry about it, but i need to finish this school project for june, and i'm a bit in a hurry, and nobody answered...i got stressed. Sorry again won't happend anymore. :(
Another question about it, But if i'm trying to desing a bass reflex with 2 drivers. How do i start? I start doing the calculation with one driver and the number of ports i want, and once i have it calculated for one. How do i change the values for two drivers? How do you associate 2 Vas drivers? Or associate 2 Qts,Qms,Qes?etc... Like electronic resistance?!?!:S Thanks a lot for your help. Really appreciate it :) |
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Lee In Montreal
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Posted: 02 April 2011 at 5:07pm |
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Hi endre
I don't know if have found your answer yet. Most ports are round simply because it is cheaper and easier to stick a piece of round ABS pipe on your baffle, than cut more wood to make a square ports. But basically as long as the area is respected, square or round doesn't really matter. The surface of a diameter is 3.1415 / 4 x D^2 |
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subbass wrote:
