Joe X

Follow the manufacturer's specs except for tuning, keep tuning 32-35Hz if you want to listen to all the low tuned music, A decent calculator is Torres which you can find for PC. Solve a few design samples, I have posted many and when you get similar results you know your calculator use is correct.

They give plans, see if that fits: https://ddaudio.com/wp-content/uploads/2020/01/box_plans_layout-8c.pdf

For two 15s it is not possible to install the below, the best way is deleting the backseats, you may or may not be able to put the box over the seats but in case of a collision you could end up severely injured or worse by it.

From your measurements I get like 1.37 cubic feet tuned to 41.75 Hz and a port area of 36 square inches. Port area is twice to 3 times what is needed, tuning is sky high, no wonder you are getting the results you describe. And yes only plugging the port can fix that box. Back to the drawing board I guess.

You are gaining half a cube from reverse mounting the subs so the 1.5 cubes left are very little difference so give the old box a try, you have nothing to lose. Pick a worthy amp and feed it with a worthy electrical, that is actually what is going to make a difference.

Those new ones will work on a somewhat larger box, you can reverse mount the drivers to gain internal airspace. I would definitely try your current box before building a new one. I don't think you will get substantial gains with a new similar sized box, let us know the result of your tests.

It's a mistake with the subs wiring, typically one of the subs has inverted polarity with respect to the other one, just check a wiring diagram to find out what you did wrong.

You don't want to fire the sub up in a trunk car or nearly impossible to control rattling will result.

This design is already for 15s looking at the sub cutouts, you just need to do a double layer baffle on top and you should be good to go, you don't need need a double layer baffle where the subs are now.

What are your max box dimensions that will it in your vehicle?

If those are 6500W RMS Watts even your alternator is not enough, on the battey those systems need many batteries not just one, say one on the front and one or more in the back.

You don't want to have a port length over 40" to avoid port resonances in your playing frequency range, also when needing a longer port you want to avoid taking a second turn. As for your latest Torres looks petty good.

Some feedback: The driver displacement should be around 0.15 cubic feet for a higher power 12 inch sub. Your port area is definitely low and should be around 40-43 square inches to keep maximum port airspeed around 25 m/s, Also because the amount of power you should have a bracing plan like cross braces, a window brace or such. That's about it.

Clearly you don't know how to use the calculator. Your port area is low also at 36 square inches, should be around 50 squaw inches, check with sundown. The port length in win isd is for non slotted round ports so for a slotted ports that is mainly why you see a difference.

This is what I was suggesting you above, you get actually more power per driver and you don't have to buy a crossover to use as high pass filter, I actually don't know if the input impedance of the passive crossover gets affect by only using the high pass filter and leaving open the low pas filter

Download from here: https://damoreengineering.com/pages/track-downloads Get them into the flash drive and you are good to go.

Actually those are not RMS watts and you can tell as follows, the fuses are 2x40A so the maximum input power is 14x80 = 1120W, if it says it gives 320x4 = 1280W which is greater than 1120W so it is impossible that those watts are RMS. So RMS watts are 320/2 = 160W RMS at 2 ohm and since that is divided for two speakers (in parallel) you get 80W per speaker. But if you do it like I posted above (using all 4 speaker channels) you get 200W/2 = 100W RMS per channel, and since you have one speaker per channel you get 100W RMS per speaker. Maybe it me that didn't explain myself well. Besides remains to be seen if those high pass filters are available for the 100Hz and the power being used, I don't think they are available commercially.

Looking at your amp specs, you can not bridge to 2 ohm (as it's often the case with speaker amps) so why wire at 2 ohm. Also you usually don't feed highs to mid range speakers. So what I would do is run the front channels to the SPX speakers an the rear channels to the NPX ones and use an electronic crossover (or DSP) before the amp to send 50-100 to the mids and 100-20K to your full range speakers. If you wanted to take advantage of the 2 ohm power output of your amp you should run 2 ohm speakers, there are some in the market, JBL car speakers are usually about 2 ohm and there are some others. Sound quality wise an electronic crossover delivers far better results and they are very flexible so you can always send the frequency range that the drivers can deliver best. I cannot think of a single case where passive crossovers were better for a setup.

Can you name the speakers that play from 50Hz and the speakers that play from 100Hz? You could place a high pass filter to the speakers that play from 100Hz and have a 4 ohm input impedance if such device exists commercially. But I prefer to know what speakers you have before offering a specific suggestion.

As long as you use the proper gauge you can run ground from battery to battery no problem, in fact is the best ground you can have and in a truck the line will not be that long, just make sure gauge is what is needed. Also don't forget big 3, it's extremely important.

What amp do you have? Many speaker amps will let you high pass the output to 50Hz without the use of a passive crossover.

Well, provided you have the space for BP6, your answers can be found through modeling software, you can have flat gain for ported as well as a BP6 design, the drivers to be used are also a big factor. Also no point in tuning to 20Hz if your vehicle has a cabin, cabin gain makes unnecessary that low tuning, The rear chamber tuning should be closer to 30Hz and your front chamber should be around the mid 50s to transition to the front stage at least at 60, the front stage usually won't e able to play lower than that. If you can't model find someone that routinely builds 6th BP for advise.

You can just change the box position / orientation, fire the subs differently etc. to avoid flex. If your box is setup the best way and you don't want to change it then there is a way to properly unmount any panel of every car, if you don't know how to just look for some video on youtube to show you how, there are plenty of videos, you will find what you need in no time.

I find 15" subs a good trade off between box size and output obtained also 2K is a nice amount of power that will not require big electrical upgrades so I am not surprised you are getting good performance from your budget system. Sure some pics would be nice to see, pics are source of inspiration for many people looking for a well put together budget system.

I would do a couple of things: 1) install a voltage gauge connected to the power terminals of your amp, preferably a fast one like the one SMD sells but a cheap one will suffice and then take note of your minimum and maximum voltages while playing at high level and then post those result on here. 2) I am really serious about the advise I posted before, setup your subsonic filter to 30Hz on your skar amp, that will prevent low inaudible frequencies to be amplified, that results in reduced current draw and potentially cleaner sounding bass. Then I don't know that battery but the correct battery to use should be a deep cycle one not a regular battery. Let us know your voltage results, in any case if your minimum voltage is no less than 12.5 volts you are not damaging your electrical, even if the headlight dim and then you only have to find a fix for the headlighs. If your minimum voltage goes down to 10V or so then likely that battery will have a reduced lifespan.