View Full Version : multiple ports

01-02-2003, 08:58 PM
Ok, so I had this awesome box designed in my head...

it featured quite a lot of angles, so I had to do some more calculations than a normal rectangular box...

after testing the volume in winisd pro, i was convinced...

everything was all fine and dandy......until I saw the port velocity... i remember in winisd beta, the mach figures would turn red after .16 or .17... I assume this would be audible air turbulence... but in winisd pro, the velocity was off the scale...way over scale..I'd need 8 ports to reduce that to a minimum...

Hmm, so alright, I thought I'd go with 4 X 4" ports instead... so the velocity dropped a considerable deal, but the length...whoa...50"?? 90"??? wtf???


1. If I use 4 ports, then do I divide the total length by 4? or do all 4 ports have to extend to that impossible length?

2. So I thought about a slot port too... 5cm opening would create too much turbulence, so i added just a couple more cm... but the length would sometimes reach another 50~70"... so bend the ports, yeah... but it would mean that I'd need more than one bend, cause the maximum width I have is 37" (with 0.75"MDF).. what are the consequences of having a 180 degree bend? What if I have about 2 180 degree bends? (aside from the volume that the port will take)


01-02-2003, 09:16 PM
having more than one bend shouldnt matter so long as the overall port length isnt affected....

01-03-2003, 01:19 AM
Originally posted by Jmac
You want to keep port velocity below 30 m/s, although some people would consider a 35-40 m/s peak acceptable ...

hmm... well, what else can I do about the impossible length?

for instance...

2 X 3" ports

30" length.... does this actually mean two 3" ports, with a 15" length, or must BOTH the ports be 30"?

01-03-2003, 12:51 PM
i would think it would be 2 ports 3" in diameter and ech 15" long...... i recomend actually using pvc pipe...that way u can ge the u joints and all to make the port......but whatever works for u.....peace

01-03-2003, 06:26 PM
ok i think i was thinking that the original was one 3" port that was 30" in length.....sorry.....jmac correct me if im wrong....but couldnt he go w/ 4 3" ports 15" long then??? or is my logic flawed?

01-03-2003, 06:50 PM
lost me?? ohh well....i probably wont ever go ported so ohh well