*6th Order* Sundown E8v3s??

[jabo6692]

So i recently got a pair of the new sundown E8 v.3 subs, dual 2 ohm. I've been messin around on winisdpro and i've come up with a parallel tuned 6th order for these babies with the objective of higher efficiency at higher freq over a conventional low tuned ported box. These woofers also appear to be highly oriented for ported enclosures according to the EBP so i assume they wont do too bad in a 6th order.

*I'm curious to see what other more experienced bandpass experts have to say about my design in terms of its port placement, cu ft ratio, port area, whether its COMPLETELY WRONG BRO!!#!, ect.

*I don't care for responses like "ur gonna blow ur shit up" and "fuck 6th orders" by people who must have been abused by 6th orders in their early childhood, im curious about sixth orders and i wanna start somewhere so don't even bother brocephalopod.

*really just lookin for new knowledge and advice on 6th orders with 8 inch woofers which seem to be quite rare.

-------------------here's teh data:

- front chamber is .53 cu ft tuned to 66 hz w/ 16 sq in port area

- rear chamber is 1.49 cu ft tuned to 36 hz w/ 24 sq in port area

- subs will be inside rear chamber firing into front chamber

- ports are facing opposite directions, if looking straight on at woofers, rear chamber port opens left, front chamber port opens right. (donno if this matters, i just didn't want the two ports directly next to each other so i put em on opposite ends)

heres a link to my sketch up download:

http://sketchup.google.com/3dwarehouse/details?mid=5bcfd206989351a721e84b8eebc8573c

the gain in winisdpro showed as following from 30-80 hz 5 hz interval with a 25hz butterworth infrasonic filter and 100hz butterworth lowpass filter enabled:

30 (-8.1db)

35 (-.52db)

40 (1.2db)

45 (1.7db)

50 (2.4db)

55 (3.2db)

60 (3.6db)

65 (3.3db)

70 (2.4db)

75 (.89db)

80 (-.9db)

tks

[Chris Hammer]

In 4 pics.

[Joe X]

I would start by telling what vehicle, amp are you using, and telling why do you think those port aimings are adequate.

[jabo6692]

'98 toyota 4runner, kicker zx 2500.1 @ 8 ohms running im guessing 625w rms total to both woofers (which are rated conservatively at 300 watts) for now. the window in the front of the design is for loading the woofers, (will be sealed by removable sheet of mdf).

As for port direction from what i've read the point at which human hearing sound localization ends is around 80hz so im guessing facing the ports in opposite directions will not seriously affect the response. I faced them different directions because i normally see parallel 6th orders with front and rear chamber ports pretty far apart from one another. Will this adversely affect my phase tho?

As for port area, i've got 16 sq in per cubic foot for the rear chamber and about 30 sq inches per cu ft in the front chamber. i've read that at least 16 sq inches port area per cubic foot should be used for bandpass boxes to avoid port noise.

as for how well this design will sound in my large cabin, i have no idea. i'm lookin to make the best out of these 8s and have a little fun with bandpass designs.

[Bradprobert]

when you calculate port area to avoid port noise you must keep the air velocity coming out of the port between 2%-9% the speed of sound. i usually try to keep it around 6% when you power subs to recommended RMS power. the reason is to maintain a more linear cone movement.

the best way to calculate your ports air velocity is to use win isd(personal preference). 2%-9% translates to 22.3-100.6 ft/sec. 6% being 66ft/sec.

i want to emphasize this is only for port noise and is just an easy reference to go by.

[jabo6692]

Thanks for the tip brad, the air velocity for my rear port peaks at 69.6fps @ 34hz , and 20.5fps @ 61hz for the front port. think the low air velocity in front port will be a problem? I've also heard you want the air velocity in the rear chamber higher than in the front chamber to help control the cone. that may only apply when its tuned in series tho.

[Bradprobert]

I personally don't have any experience with 6th orders so hopefully joe will chime in. For me I think the 61hz side seems a little low. You might run into bottoming out issues? Especially down in the lower frequencies. But since it has the other chamber that might help with cone control making it a non issue. Don't quote me though. Does that seem right joe?

Edit: by 61hz side I'm referring to the 20ft/sec air velocity.

[jabo6692]

hold up, i had the port area wrong in winisd, it was set at 8x8 instead of 4x4 lol actual peak of velocity is of front chamber is 82.2fps @ 60.85 hz

[Bradprobert]

hold up, i had the port area wrong in winisd, it was set at 8x8 instead of 4x4 lol actual peak of velocity is of front chamber is 82.2fps @ 60.85 hz

And I'm like wait, hold up, please let me roll up... Haha I just died laughing! Again I'm not sure. It's bout bout time joe shows up smh.. haha jk

[jabo6692]

hahah ca$h out, but yeah, this box is for every day use, hoping to surprise a few people with its output, but nothin spl related. Im hoping it will sound decent too. any ideas for improvement on the design? fatal flaws?