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View Full Version : 6" or 8" port? (two 12" type Rs)



moparerrnocar
01-30-2013, 03:27 AM
Im trying to decide if I should do a 6 or an 8...

The box is 23x36x12 going in a 97 grand prix with only 1500 rms. Being as I don't know what frequency I like most since I have such a diverse taste in music, my plan is to build the biggest box I can and then experiment with different length aeros. I'll probably be making my own from pvc.Originally my plan was to make two 6" ports that adjust 2" (coupler), one 12-10 (32-34hz), and the other 8-6 (36-39hz).

The 6" gives me 6" per foot, will this be enough? 8 gives me 11.5"-12" per foot. Only issue with the 8" is it has to be twice the length and requires a 90 and a lot of volume and wouldn't be as easily adjustable. The 8" would have to be 28-23 (32-34hz) and 19-15 (36-39hz), in terms of adjustability that range won't be possible w/o making 3-4 ports. I realize I can just keep cutting it shorter, but Id like to be able to go back and forth to see the difference. The second concern is volume, the 6" nets me 4.5-4.7 (12"-6") but the 8 nets me 3.9-4.3.

My goal for this box is to increase my efficiency w/ added output. Currently running 3^3 @ 42hz w/ 11.5 per foot. Its way too boomy and horribly inefficient, I get some pretty bad voltage drop with my diehard platinum agm bat and 0awg and factory 105amp alt. I planed to upgrade to an ho alt, but Im hoping a new box will reach the mechanical limits b4 current limits.

How much difference will 1/2 cube and 6" of port area make? What's better for my intentions, big box small area or slightly smaller box with twice the area, and why?

Thanks

Sorry for such a long post btw....

n8skow
01-30-2013, 11:40 AM
Looking at Alpine's optimum box specs - looks like they recommend 1.3 cubes of airspace per woofer, with 15 square inches of port.
They also rate the power handling at 500 watts RMS per woofer.

Based on the numbers you've given - you'd have about 2.07 cubes of airspace per woofer (net) and ~750 watts of potential power per woofer.
Overpowering woofers in an oversized box is going to be a recipe for disaster.

I'd bring your box size down, and use a single 6" aeroport.

moparerrnocar
01-30-2013, 09:20 PM
Yeah,... Anyone with experience care to help.

No offense N8scow, but you clearly have no experience or knowledge with type Rs. Firstly, I never mentioned the gen or model so you just assumed they where the 3rd gen or older (2010-older). I have the 4th gen 600rms (2011). Type Rs are always way under rated. They are well known to take 1000rms daily. The new 5th gen handle 1000rms and are basically the same woofer mechanicaly. Secondly, type Rs like 2-2.5 cubes. You can argue, but alpine (like most popular manufactures) spec their subs for a wide range of vehicles and listeners thus the small box and high frequency. Ftr, type Rs take beating, I've been clipping the **** out of mine w/ dirty power for two years running. They still sound great, but begging for more power and or efficiency.

n8skow
01-30-2013, 11:21 PM
You didn't list what subs you have specifically - so I took a guess. My bad...
At any rate, good luck with your build.



Yeah,... Anyone with experience care to help.

No offense N8scow, but you clearly have no experience or knowledge with type Rs. Firstly, I never mentioned the gen or model so you just assumed they where the 3rd gen or older (2010-older). I have the 4th gen 600rms (2011). Type Rs are always way under rated. They are well known to take 1000rms daily. The new 5th gen handle 1000rms and are basically the same woofer mechanicaly. Secondly, type Rs like 2-2.5 cubes. You can argue, but alpine (like most popular manufactures) spec their subs for a wide range of vehicles and listeners thus the small box and high frequency. Ftr, type Rs take beating, I've been clipping the **** out of mine w/ dirty power for two years running. They still sound great, but begging for more power and or efficiency.

RicksI30
01-30-2013, 11:23 PM
I would use the 8 for sure.

moparerrnocar
02-01-2013, 10:25 AM
Idk what Im thinking, I don't even have room for an 8" port... So much for that idea.

brandon_s0854
02-01-2013, 10:32 AM
If you're not chasing numbers, a 6" with a good flare would be fine with those subs. You might gain 1dB with an 8" depending on box design, but you wouldn't hear a difference. I'd bet money on it.