Inetba Posted August 26, 2015 Author Report Posted August 26, 2015 It seems like one 18" sub on 3,400 watts will have port noise no matter what unless it's a hilariously oversized box with an obnoxiously oversized port. Like a 10 cubic foot box would need a 10" wide aero port that's 4 feet long. Or a 16 x 8 inch slot port that's over 45" long.I may just deal with port noise below 32 hz.
Inetba Posted August 27, 2015 Author Report Posted August 27, 2015 Been doing some more fiddling around with WinISD, it has been confusing to say the least.Input all the stuff from my current box. Everything looks alright (But their measured SPL after cabin gain was waaaaay too low.) Then I look over at the airspeed and wtf? They're saying I'm peaking at 1,240 ft/s @ 19hz?! Now I know that's not right or I'd be hitting much higher than 140db! That's faster than the speed of sound.
Inetba Posted August 27, 2015 Author Report Posted August 27, 2015 Decided to try out WinISD beta and using all the exact same information, it gave me a port velocity of 11.2 ft/second. Considering I never hear any port noise, this seems more than accurate. In which case I will be fine without 17 10" aero ports.
zxsonnyxz Posted August 27, 2015 Report Posted August 27, 2015 Are you sure you're doing it right? STD Passat Build 151db+STD Omega BuildMitsubishi Colt Build - Alpine|Focal|PeerlessHome Stereo BuildSmall Tang Band build - 4" fullrangeBox for 4 8"My Saab 9000 Build- I'd be very happy if you cared to check out the logs and give feedback!
Inetba Posted August 27, 2015 Author Report Posted August 27, 2015 I'm never sure. But that's most of the fun! And that's why we build our own boxes instead of buying store built. The one thing I love about aero ports is being able to adjust them. Being able to switch out between 27hz tuning and 40hz tuning is just awesome. Want to absolutely crush 20hz? Sure thing! Want to literally blow socks off at 48hz? No problem!
Joe X Posted August 27, 2015 Report Posted August 27, 2015 For your reference here's what I get for a SP4 18" D1 on 3400W 6 cubic feet net @ 32Hz, single 10" round port: It looks like the single 10" will work for that sub on the low 30s tuning range.
Inetba Posted August 27, 2015 Author Report Posted August 27, 2015 Hmm... Now the $200 question... 10" sonotube, or two 6" PVC pipes... Sonotube would look soooooo much cooler. But I already have PVC laying about. Google says sonotube has better airflow. Sonotube wins!
Triticum Agricolam Posted August 27, 2015 Report Posted August 27, 2015 Hmm... Now the $200 question... 10" sonotube, or two 6" PVC pipes... Sonotube would look soooooo much cooler. But I already have PVC laying about. Google says sonotube has better airflow. Sonotube wins! I'd vote for the 10" sonotube, its 1/3 more port area than two 6" ports anyway. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds:
Inetba Posted August 27, 2015 Author Report Posted August 27, 2015 Now I know they say, "put a minimum of port width between the end of the port and the wall" but do I really have to keep the end of the port a minimum of 10" away from the wall? Could I do 6"? Or 5"? Just wondering how it would effect things.
Triticum Agricolam Posted August 27, 2015 Report Posted August 27, 2015 No you don't have to have it 10" away, though 10" would be ideal. You only need it to be 1/4 of the diameter (so 2.5" with a 10" port) away to have the same amount of area around the port as the port has itself. Now it if you only had it 2.5" away it would almost certainly lower the tuning some, but it wouldn't be choking off the airflow. If you can get 5" you should be fine. ETA: Flaring the end of the port will help significantly as well. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds:
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