simple question needing simple answer/opinion

[alaskanzx5]

2 Rockford t2d415 on a single t1500.1bdcp at first (going to add a second)

5.51 cuft box (small for what most like for 15s but its with in recommended by Rockford plus will be over powered)

2 6" pvc ports ( will flare them )

now here is what im wondering.

im going to be going with a 38hz tuning for the meter (looking to peak around 46-51hz 51hz being cars resonant freq)

daily I want closer to a 35hz tuning and to do this my plan is to invert the subs making the box 5.83cuft and use longer ports. with the raised volume and 2" longer ports according to a port length calculator on the carstereo.com webpage would give me a 35hz tuning.

port length for 38hz 15" 2.75" external

port length for 35hz with the subs inverted is 17" 4.75" external

35hz with out inverting the subs I would have to go with a 18.25" port 6" external

box dimensions require me to have an external port.

now would it be worth the trouble to invert the subs to increase enclosure volume by .32 cuft and a slightly shorter port length or should I just stick with the 18.25" port for daily?

[Joe X]

Just did a quick Torres test with 4 4" ports instead of two 6", all of them 10" long, it gives 39Hz tuning with a net of 5.51 cubes, if one of them is plugged tuning comes down to 35Hz, this just illustrates another way to change your tuning but without modifying anything, it needs to be done right though, making sure that plugging one port doesn't leave you with low port area for that lower tuning, likely not too hard since lower tuning requires lower port area, this can also be done with sectioned slot ports.

[alaskanzx5]

I thought about that but worry about port noise when blocking a port to lower the tuning.

Max dimension are

40" wide

19"deep

19"high

with that I will have to do some work to get it in and the trim panels back on. Maybe even some trimming of plastic.

[bbeljefe]

I don't think any of what you're talking about is going to net you an appreciable difference in output. The reason why is that in order to improve low end extension, you need box volume first, then tuning.

Put simply, you can tune a small box as low as you want to but the lack of volume is going to cause a steep, cliff wall like drop off on the bottom end of the spectrum.

But... you'll never know unless you try it. :-)

[alaskanzx5]

I know i've been using winisd and that's why I wad thinking inverting the subs to help gain a little volume for daily. the higher volume makes it a little more flat for the response.

Best way to do it will be to build and test I know, just trying to get some ideas.

[Joe X]

I thought about that but worry about port noise when blocking a port to lower the tuning.

Max dimension are

40" wide

19"deep

19"high

with that I will have to do some work to get it in and the trim panels back on. Maybe even some trimming of plastic.

I would worry too, repeated the test but this time 5 4" ports 14 1/2" in length giving 38.5Hz, plug one and you get 35Hz, at some point you should be able get proper port area for both tunings if you just have enough space. One way or the other it can be a lot of effort to do a box that will work great both burp/daily.

[alaskanzx5]

im willing to do the work. I was told I cant do it so now I want to lol. when ever im told I cant do something I find a way to prove people wrong. even if I end up having to move the back seat to gain an extra inch of depth and height ill do it. wouldn't be hard to do it, would just have to get a small .25" rod bent and welded for the seat to latch onto at a different angle. the bottom depth is actually somewhere around 25-28" and top depth at 19" so if I have to I could just move the amp to the spare tire well and instead of one larger extra battery do 2 smaller batteries on the sides of the box on top of the wheel wells.

angling the wall of the box with the seat with a bottom depth of 28" and top depth of 19" 40" wide all on torres so before going with any of these ideas I would double check tuning with other calcs and winisd to make sure I get a more accurate tuning freq.

2 6" ports at 12.25" gives me 33.36hz and 7.42cuft net

3 6" ports at 12.25 gives me 40hz and 7.22 cuft net and plugging a port gives me 33.36hz

5 4" ports at 12.25" gives me 35hz with 7.35cuft net

5 4" ports at 9" gives me 38.14hz 7.49cuft and blocking a port drops tuning to 34hz roughly

dropping the bottom depth down to 25" loses roughly .8cuft net for the 6" ports and roughly .5-.6 for the 4" ports. tuning only changes by roughly 1-2hz for all the different options listed.

didn't mess with different port lengths for the 6" port option but I did for the 4" port option and with the slightly smaller box (bottom depth of 25") I would go with about a 1-2" longer port possibly to drop the tuning to 34-35hz with one plugged and 37-38hz with out the port plugged.

these are just a few ideas I have though. I can make it work one way or another. I could even fit a small battery under the hood along with a group 31. car has a cold air intake and so the space where the airbox was is roughly 6" high, 10" deep 11" wide. the 4 channels are going In the hatch door so I wont loose any area from those and pending the final box design I can move the sub amp(s) around from the back of the box between the seat and box or under the box in the spare tire well.

I have plenty of options and choices to pick from and test. just trying to see if I can get other ideas. my goal is more of a daily setup but getting on the meter is an extra perk to me. if I can beat a 146 sealed on the dash around 46-51hz ill be plenty happy with that.