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View Full Version : Help with a ported box for 4 REX 8's



db138
07-06-2011, 01:16 PM
I've built many sealed boxes over the years, but this is my first attempt at building a ported enclosure. I have four RE Audio REX 8's, each currently running in .35ft^3 sealed after displacement. I want to put them in a ported box to see how much more output I can get. I have tried to play around with the numbers in WinISD, but I keep getting errors with the program. I would not be against using round ports instead of a slot port, as long as someone helped me with the plans. I'm aiming for 2 cubes and tuning to 32Hz - RE recommends 35, but I've read that most people tune the 8's to 32. Here are the numbers I have using the box designer on reaudio.com using 3/4" MDF:

38W x 13H x 12D
Port height: 11.5
Port width: 2.5
Port length 1: 8.75
Port length 2: 20
Total port length: 33.25
Square port diameter: 6.05
Square port area: 28.75
Port volume internal: 955.9375
Box volume: 1.985
Tuned frequency: 32

T/S of subs:
Electrical Q Value -Qes: 0.38
Mechanical Q Value -Qms: 4.21
Total Speaker Q Value -Qts: 0.34
Free Air Resonance -Fs: 22.8 Hz
Equivalent Compliance -Vas: 27.1 liters
One-Way, Linear Excursion -Xmax: 12 mm
Efficiency -SPL 1W/1m: 81.2 dB SPL
Effective Piston Area -Sd: 195 cm^2
DC Resistance -Re: 3.2 ohm
Nominal Impedance -Znom: Dual 4 ohm
Thermal Power Handling -Pe: 175 W
Force Factor -Bl: 15.4

I can fit them on the face of the box, but it is tight - round ports might be better because that would give me more room to mount the subs. They are being powered by an Alpine PDX-1.600, birth sheet says 666 watts. Thanks for any help.

mast240
07-06-2011, 01:20 PM
what errors are u getting in winisd?

db138
07-06-2011, 01:24 PM
I don't remember now, I was messing with it a couple days ago. It kept freezing up and I'd have to ctrl+alt+del to get out of it.

mast240
07-06-2011, 01:28 PM
once i get off work, i'll plug the parameters in and put a screenshot up for you

bgowdy31
07-06-2011, 01:45 PM
curious.... y not port them

surreal
07-07-2011, 03:52 AM
^Reading comprehension.

Dont believe one particular value is right for you just because others believe so. Ultimately, what are you trying to get from this system, and what are your overall listening expectations?

db138
07-07-2011, 10:36 AM
I lean more towards SQ, but I like to be able to get loud when I want to. I guess I'm just looking for more output. I'm decently satisfied with the way they sound and blend with everything else I have... I just get the feeling that they should get louder on 600w RMS than they do. It's much cheaper to buy a sheet of MDF and play around with a new box - not to mention it's a learning experience - than to buy new subs. After looking and measuring again, I think it would be better do round ports instead of a slot port. With the slot, they barely fit on the face of the box - 38" is the absolute widest I can go. Maybe the subs in line across the face and 2 round ports in the top corners?

My other gear:
HU: Pioneer AVH-P3200BT - getting ready to swap it out for a Kenwood KDC-X794
Components: CDT Audio CL-61A in kicks with the Upstage kit in A-pillars
Midbass: Peerless SLS 6.5" in doors
Amps: Alpine PDX-4.150 and 1.600

Edit: Oh yeah, these are in an '05 Scion xB

RAM_Designs
07-07-2011, 10:58 AM
You can stagger the subs and do a slot port still. 2.5-3ft^3 with a 30-33hz tuning works well with these.

surreal
07-13-2011, 06:44 AM
They should work well in a 4th order. PM me your max working dimensions and Ill see what I can come up with.
Also note, I dont get on here much. So if I dont respond immediately - I apologize.

Phoenix Risen
07-13-2011, 08:35 AM
actually staggering the subs and using a 6'' aero would look pretty slick, the aero would be about the same size as the subs. and with a 2.5 cube box should be pretty close to what you need (if im wrong for what these subs like i apologize i havent used them before)

only problem with that is making sure you have the depth to run the aero.

db138
07-19-2011, 08:36 AM
The max space I have to work with is 38" wide, 18" deep at the bottom, 15" tall, and a top depth of 12.25". The angled side is against the seat backs. Box would be either rear or up firing.

How much port area should I be looking for - would two 3" ports be enough or would I need to go larger?