sub upgrade

[dukesofhazzard]

thanks, Ill still have to buy a sub though, and I feel if I am going to buy a sub I feel the extra cost of a 12" and enclose it will be worth the upgrade. I like the pics of the install though, thanks. Keep other pics and info coming thanks. I am just so glad don't have to buy another amp, so should be a fairly cheap upgrade. Just been so busy haven't even had time to look at the boat.

[dukesofhazzard]

another question for all the stereo gurus, what is the difference between a round port and slotted. I see for the wetsounds xs12 sub on the wetsounds site it shows a 4"round port 10" deep for 40hz.?

[chpthril]

From a tuning standpoint, not really any difference when the port opening, length and tuned Hz are the same. This is achieved by manipulating the port opening in2, length and enclosure net volume. From an physical standpoint, an ABS plastic "Euro" port takes up less internal space then a constructed wood port. This can help reduce the external enclosure dimensions.

[BCRider]

Dukes, when you start making your box make 2.lol. I'm looking to upgrade as well. Never ended up doing it this year.

[dukesofhazzard]

I hope next week to start looking into it, I know a guy who knows a guy for a sub so just waiting for a price. bc rider pm about that. I don't think a box will be too hard just gotta get in there and see if if and what or how much I need to move.

[chpthril]

Just make sure you guys decide to use the same woofer.

[dukesofhazzard]

ok so I got my woofer, my buddy is a supplier so I got a great deal on a diamond audio d6 12. Should fit in perfect for the power I have to supply to it. Now for the box. the manufactures states a 1.25 cuft gross box. However that is for a 4" round port 20" long. I want to go slot. So I assume I will make the box 1.25 gross with the sub and add extra size for the slot port. I found a site that helps for tuning but I can't believe how long it says the port has to be if it is a 12" slot 1.5 " or 2" wide its like 40" long. So before I start my build does that seem right. All these numbers are up in the air right now as I have to decide on the actual meas. but this has to be fairly close. I will use 3/4 birch ply, glue and screw.
sub specs fs 32.4
xmax 17.8
600/1200w
fb/f3 40/34
vb ft^3 1.25

[chpthril]

a 4" round

a 12" slot 1.5 " or 2" wide

If these equal the same sq/in, then the length would be the same, taking into account the volume taken up by the slot ports .75" frame work compared to the thin ABS walls of the euro port. Providing both scenarios are tuned to the same hz.

[dukesofhazzard]

thats what I thought too, but when I use this it seems diff. http://www.carstereo.com/help2/Articles.cfm?id=31. Maybe I am missing something. But I sq in is sq in whether tube or square.

[dukesofhazzard]

hey mike I got this other calc. too
4" tube id. divide by 2
multiply x 2 x 3.14=12.56
take sq rt of 12.56= 3.54

so a square port would be 3.54*3.54 x L

so if a 2" slot was used 12.56/2= 6.28
so 6.28 x 2" x L
this makes sense but when I see most boxes the slots are around 12" high 1.5" wide and 20" + long. which def is not the same calc.
thanks

[chpthril]

Are you trying to hit the same hz with both scenarios? if so, what Hz?

[dukesofhazzard]

well the sub manual says 34 or another spot says fb/f3 40/34, So I was assuming 34 hz. If I figure 4" id, so 2x2x3.14=12.56 x 20" for length =251 in^3
When I use the port calc on website When I plug in 1.5" wide port and 12" H it gives me 29", 1.5 x 12 x 29 = 522 in^3 so way diff. thats why I am confused. with the port calc site the larger the opening of the port the longer the port becomes. the brochure I have says gross internal vol 1.25 ft^3.
thanks

[dukesofhazzard]

well the sub manual says 34 or another spot says fb/f3 40/34, So I was assuming 34 hz. If I figure 4" id, so 2x2x3.14=12.56 x 20" for length =251 in^3
When I use the port calc on website When I plug in 1.5" wide port and 12" H it gives me 29", 1.5 x 12 x 29 = 522 in^3 so way diff. thats why I am confused. with the port calc site the larger the opening of the port the longer the port becomes. the brochure I have says gross internal vol 1.25 ft^3 for vented box
thanks

[chpthril]

hey mike I got this other calc. too
4" tube id. divide by 2
multiply x 2 x 3.14=12.56
take sq rt of 12.56= 3.54

so a square port would be 3.54*3.54 x L

so if a 2" slot was used 12.56/2= 6.28
so 6.28 x 2" x L
this makes sense but when I see most boxes the slots are around 12" high 1.5" wide and 20" + long. which def is not the same calc.
thanks

You have to tune the box to the woofer, you cant tune the woofer to the box. If these are pre-made boxes with fixed specs, then they are likely incorrect for 99% of the woofers loaded in them. Nothing wrong with a 12 x 1.5 (18 in2 area) for most woofers, but theres no way the length is going to be the same IF the woofers net volume and tuning Hz are actually designed.

The reason you are seeing such a different in port length between a 4" round and 12 x 1.5 or 2.0 inch slot, is the area difference of the two. To maintain the same frequency, the length would have to changed, or, if you retained the same 20" port length, the tuning Hz would have to change.

Hard to find info on that woofer, but here is what I got. 40Hz and a woofer volume of 1.25 ft3 seems to be what the manufacturer suggests. That 1.25 ft3 is for the woofer, not the gross internal that accounts for the port construction. With a 12" port, one box dimension is going to be 13.5". All you need now is to figure out the other 2 dimensions, one being the depth, that maintain the 1.25ft3 net for the woofer and 40hz tuning frequency for the port with an area of 18 in2.

[dukesofhazzard]

okay, I fully understand that the box must be tuned for sub, that part I get, and I get the part that if the cu ft of the round port is amount X, then a rectangular port should be equal to the same cu ft of X, it was just when I used a couple of the box builder design programs the port recommended from them was way diff. So if I understand correctly, and correct me if I am wrong mike, the shape of port does not matter, just the same volume?!

here are the specs for my sub d12d2
if you look at the enclosure section it says the volumes below are gross internal volumes, driver and vent displacement has been accounted for.
so with these specs do you still its 40 hz in the thiele parameters Fs =32.4hz in the enclosure section it says Fb/F3 (hz) 40/34
with these I thought the box would need to be 32 hz. Yes/NO
thanks again
appreciate it



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