are you going to reply to this thread or did i type it all out for nothing?
https://www.s2ki.com/forums/showthread.php?...&threadid=34866

 

oh sorry, I didn't know you were expecting answer from me...I was just asking some questions and for the most part, you answered them...

I think I gained some knowedge into this whole port enclousre design and definitely want to play with your box program a bit. but in the end though, I think there are still two main issues that would make it difficult at times for me to use a ported enclosure:

1. enclosure size, despite programs that can optimize your enclosure size, it will still in general be slightly bigger to moderately bigger than a sealed enclousre, whcih may present a challence since most of enclosures are fiberglass and I have to squeez every ounce of space to get the necessary room.

2. port size and length, for example, I am building a enclousre that is 40"x20"x4.5", it would extremely hard to get a port into this kind of space.

also, does your box program take into consideration the transfer function of the vehicle? I hav enever used that progmra before.

Thanks gaain for your response...

Bing

 

yes if you can put an RTA in the car you can enter the different freuqency points and add a value + or - db for that frequency and save it. so it will reflect the exact frequency responce. or you can use the general one provided that boosts at 50 hz

it is true that the ported boxes will be a little bigger than a sealed box but the fact still remains that even if you built a box the same size and ported it, it would still out proform the sealed box of the same size in both SPL and low frequency responce

btw in a box like you described you can always use a sloted port and use the inside walls of the box for part of the port. thease slotted ports are easy to make and offer the flexibility to make a port exactly the length you want to make it because you arent limited to PVC that comes in 2, 3, 4 inch diameters. you could vary the with and heigth of a slotted port just by cutting the peices a different size.

i am attaching a plot for you this graph represents a sealed box (BLUE) of 1.2 cu ft with a JL 10W3
the (GREEN) line is the same sub in 1.2 cu ft with a port tuned at 32.64hz
the (PURPLE) line is the same sub ported and in .75 cu ft tuned to 39.28hz
as you can see the same sub in almost 1/2 the size box still plays louder, lower than the sealed box by a good margin.
here are the f3 points in the same order
53.44 hz
32.32 hz
39.67 hz
as you can see not only is the ported box lower still but 13 hz lower and almost 1/2 the size still a far better choice than sealed not to mention the SPL you gain from either ported box the smaller box has almost 6 db gain over the sealed box at 63 hz in this example. that would take 4 times the power at that frequency to achieve from a sealed box.

in the second graph you are looking at the same 3 designs but the graph is showing cone displacement notice how the 2 ported boxes have far less cone displacement (xmaxx) than the sealed box in fact the cone displacement of the ported box dosn't move as far as a sealed box until it gets to 25 hz so the myth about self distructing subs in ported boxes is false in this example unless you plan to listen to bass notes at 25 hz or lower.
all in all i feel thgere are a lot more advantages then disadvantages using ported boxes. and if i were you i would seriously consider looking into them.




write me back and let me know what you think..