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4th order design help

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sherwood71

sherwood71

Member
127
22
east coast, Canada
Vehicle :2009 Pontiac G8 GT

Location in the vehicle:trunk

Space available (Length x Width x Height):14x36x14

Subwoofer make and model:precision Power P.12D4

Subwoofer Size:12

Number of Subwoofers:1

Type of Port (Kerfed, Slot, Aero, etc.): slot port firing thru ski pass hole in rear seat (will get dimensions)

What type of music do you like?:listen to everything

Is your goal SPL or Everyday Music?:everyday

Tuning Freq (Hz):

Volume :

Questions: Will a 4th order work good with the dimensions that I have posted?

I have researched 4th orders and played with winisd but am having no luck figuring out the port.

Going to be powered by Precision Power P1000.1 at 2 ohm.

Woofer specs

Specifications

P.12D4

Fs (hz) 28.05

Qms 4.538

Vas (ft^3) 1.49

Cms (mm/n) 0.123

Mms (g) 261.63

Rms (kg/s) 17.9

Xmax 15

Xmech 22.5

Dia (in.) 9.8

Sd (in^2) 49.09

Vd (ft^3) 0.039

Qes 0.542

Re (ohms) 7.212

Z (ohms) 8

BL 26.6

Pe (watts) 800

Qts 0.484

No 0.182

1w/1m SPL 84.64

2.8v SPL 85.2

VC DIA (IN) 2.5

VC (Ohms) DVC 4

M-vd (ft^3) 0.19

Cut-out 11.13

Depth 6.375

Click to read more...
 
Last edited by a moderator:
You could fit 1.4 sealed .7 ported with a 4 inch aero port tuned to 55hz. It will play nearly flat (+/- 1db) from 20-70hz with minimal group delay, it would be a very musical box.
Click to expand...
Thanks for the reply. I will mess around with winisd and see what I can come up with using a larger sealed/ smaller ported dimensions. I was looking at the opposite small sealed/ larger ported.

Another question? Does it matter about port placement on the box? I'm hoping to have the port line up with a ski pass thru in my rear seat.

 
Thanks for the reply. I will mess around with winisd and see what I can come up with using a larger sealed/ smaller ported dimensions. I was looking at the opposite small sealed/ larger ported.
Another question? Does it matter about port placement on the box? I'm hoping to have the port line up with a ski pass thru in my rear seat.
Click to expand...
Small sealed and large ported will make it peaky. If you want it for everyday music then use a 1:1 sealed to ported ratio to a 2:1 sealed to ported ratio for a more flat less peaky response. As long as you don't put the mouth of the port near the sub it should be ok. I would use a round flared port (aero port) instead of a slot port.

 
Definitely don't want a peaky box or a one note wonder box. Looking for something like you said "musical", a box that will play everything and sound good doing it. If it gets loud doing so then that will be a bonus.

Have been playing with WinISD and drawing on some paper to figure out a box. I have come up with something that I hope will work. Trying to attach an image to the post, hopefully this works.

Can you take a look at this and see if I am on the right track?

View attachment 26557445

 
Definitely don't want a peaky box or a one note wonder box. Looking for something like you said "musical", a box that will play everything and sound good doing it. If it gets loud doing so then that will be a bonus. Have been playing with WinISD and drawing on some paper to figure out a box. I have come up with something that I hope will work. Trying to attach an image to the post, hopefully this works.

Can you take a look at this and see if I am on the right track?

View attachment 26557445
Click to expand...
I would try to move the mounting baffle over to the side so its perpendicular to the 25 inch width or offset the sub and port to each side

 
I would try to move the mounting baffle over to the side so its perpendicular to the 25 inch width or offset the sub and port to each side
Click to expand...
I was originally drawing it that way but realized that the port wouldn't line up with the pass thru. But may have to live with it not lining up. Will definitely play around some more with the dimensions.

How long would you make the 4 inch aero? Winisd is calling for crazy lengths.

Thanks for all your help with this.

 
Small sealed and large ported will make it peaky. If you want it for everyday music then use a 1:1 sealed to ported ratio to a 2:1 sealed to ported ratio for a more flat less peaky response. As long as you don't put the mouth of the port near the sub it should be ok. I would use a round flared port (aero port) instead of a slot port.
Click to expand...
Its been a long time since Ive seen someone that designed a 4th correctly to play flat. I had a few designs just like this where ported section was smaller than the sealed and were great sounding. I am going to dig up an old design for a sa 12 in a 4th that was modeled to play flat from 70 down to about 30. I wouldn't mind doing a 4th like that with the port firing through my ski hole, with a single 10 or 12

 
Ok, I build a 4th order enclosure for two Skar Evl 18's with seal side being about 6.5cf and the ported side 10 cf with a 12in wide 12 high and 6 in deep port sounds great and hit the low note really well just wanted to know is this close to spec for a 4th order enclosure?

 
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sherwood71

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