Port calculator seems off wtf? please advise

[S1R-BLUNTZWORTH 10+ year member]

I used this port calculator with these parameters and it seems waay off to me:

It tells me to make my port 6.1 inches long.. Won't it sound dirty/not nice'n'deep with such a short port? also, is 3 inches too narrow for 2 hdc315's even if it's tuned correctly? I want it to be like a windstorm in my car....

http://www.the12volt.com/caraudio/boxcalcs.asp#por

Port Type : Slot

Port Width: 3 in

Port Height: 15 in

Box Volume: 8.0 cuft

Tuning Freq: 36hz

Please advise me what to do-

Click to read more...

 

[theMessenjah44 10+ year member]

Rule of thumb is 16 sq. inches of port per cube of airspace, give or take about 20% depending on application, so you should be looking at 105-150 sq. inches of port. 3x15 is only 45, so you'll be choking those bishes out.

Try to work in a little bigger port and see what it says then //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[pr-festiva 10+ year member]

agreed,,, you'll need a port with more surface area

 

[S1R-BLUNTZWORTH 10+ year member]

4.75 is all my box can afford due to the width of the trunk. and that gives exactly 0.75inches on each side of each sub, just enough for the walls of the enclosure (the boards are 0.75 inches so it's absolutely as tight as it can possibly be crammed lol.)

I've rough guessed what the port space + subs will take up, so my box will be approx 7.5 cubes after that. It recommends 13" if port is 4.75 inches wide for a tuning of 36hz so it'll be 12in + 1 inch front baffle i guess //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

edit: 5.25 wide(if I make box .5in wider)and 13.5 +1in front baffle long

 

[OZLancer 10+ year member]

use this

http://reaudio.com/speaker_box/LPort_Box_Calc.html

tuning is off by 2-3hz (ex. 32hz would actually be 34-35hz)

 

[S1R-BLUNTZWORTH 10+ year member]

but it doesn't allow me to put in tuning as a target frequency //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif the tuning is unchangable and is stuck @ 30hz when I put in my box specs.

36.5 width

16.5 height

27.5 depth

thickness 0.75 (except front baffle)

port width 5.25

target frequency 36-37 hz(which it won't allow change)

Box is 7.9 cuft before accounting space for the port + 2 hdc315's

I am planning to have the port in the center between subs

 

[pr-festiva 10+ year member]

is this box firing forward in to the car or backwards?

 

[S1R-BLUNTZWORTH 10+ year member]

is this box firing forward in to the car or backwards?

this box is actually the absolute maximum I can fin in trunk without assembling it inside of the trunk and being permanent. So it will be removable, I will probably try it both ways since there's enough ventilation on top of the box and through the rear deck for it to be placed backwards. I've already made a cardboard decoy of the enclosure to test the removability.

 

[pr-festiva 10+ year member]

do you know the displacement of the subs?

 

[S1R-BLUNTZWORTH 10+ year member]

do you know the displacement of the subs?

70.421 Ltr each

took that from here

http://ddaudio.com/aq/HDCSeries.htm

 

[pr-festiva 10+ year member]

no thats the vas of the sub not how much it physicly displaces

 

[S1R-BLUNTZWORTH 10+ year member]

well, idunno...//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[pr-festiva 10+ year member]

4.75''x15''x16''long should get you in the ball park but its hard to say with out knowing how much the subs displace,,im going by the psp port calculator which is a few Hz off

 

[S1R-BLUNTZWORTH 10+ year member]

thanks-

well, i know that 5.25" wide port x 13" deep consumes .33 cuft of airspace(out of the 7.9cuft box, bringing it down to 7.6cuft), I just dont know the subs.

 

[pr-festiva 10+ year member]

sorry,,gave the wrong measurement,,i done the calc.for 5.25'' x15''x16 inch long