Cannoy Posted August 16, 2017 Report Share Posted August 16, 2017 Just finished my box design and it comes out to 2.32 cubic feet and tuned to 32.9 according to WinISD. The port area is 37.5" and WinISD says the airport velocity is 91ft/s, is this going to cause a noticeable amount of port noise? Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted August 16, 2017 Report Share Posted August 16, 2017 You might get a bit of port noise, but it probably won't be severe. If you are worried about it you could increase your port area a bit. "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: Link to comment Share on other sites More sharing options...
Cannoy Posted August 17, 2017 Author Report Share Posted August 17, 2017 I might try increasing the port area, but using the recommended port area from carstereo.com it only lowers the velocity by 5 ft/s. Link to comment Share on other sites More sharing options...
ckeeler11 Posted August 18, 2017 Report Share Posted August 18, 2017 Do the specs on Carstereo.com match what Fi recommends? Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted August 18, 2017 Report Share Posted August 18, 2017 18 hours ago, Cannoy said: I might try increasing the port area, but using the recommended port area from carstereo.com it only lowers the velocity by 5 ft/s. The port calculator on carstereo.com uses a formula that doesn't work well with the high excursion subs we have now. Since you have everything in WinISD I'd suggest increasing your port area until the peak port velocity get no higher than 72 feet/sec. "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: Link to comment Share on other sites More sharing options...
Joe X Posted August 18, 2017 Report Share Posted August 18, 2017 Here is a vent airspeed plot for the Fi SSD 12 latest generation on 1250W, box specs [email protected] port area 37.5 sqin: I'd doubt you will have any port noise if you do round all sharp edges inside the port (or using 3 4" flared round ports), much less if you are going to put this in a trunk car. I might add that WinISD is not designed for slot ports, if you are using one your tuning is going to end up a bit lower than expected. Link to comment Share on other sites More sharing options...
Cannoy Posted August 18, 2017 Author Report Share Posted August 18, 2017 I guess i wont change anything then. Trying to get the airspeed down to 72ft/s on WinISD would make the port almost 4 feet long, Link to comment Share on other sites More sharing options...
Cannoy Posted August 19, 2017 Author Report Share Posted August 19, 2017 What should I use to calculate port length? Every calculator I use gives me a different length. And I have looked through the forum but I see people suggest different calculators, will they all get me close enough to what I want? Link to comment Share on other sites More sharing options...
3vil Posted August 19, 2017 Report Share Posted August 19, 2017 Might i suggest you take a look here... Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted August 19, 2017 Report Share Posted August 19, 2017 16 hours ago, Cannoy said: What should I use to calculate port length? Every calculator I use gives me a different length. And I have looked through the forum but I see people suggest different calculators, will they all get me close enough to what I want? Calculating port length to get the tuning frequency you want is not an exact science. There are several different formulas and they usually give similar but not identical results. Also things like changes in atmospheric pressure and temperature will change your tuning and none of the formulas account for that. Another thing to consider is when using a slot port you need to account for end correction and there are a couple different ways to do that. Also its not uncommon for your tuning to drop a couple Hz at high volume. If you give us the dimensions of your port, net volume of the box, and desired tuning frequency I can tell you how long it needs to be. "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: Link to comment Share on other sites More sharing options...
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