Joe X

Can you post your design 2.1 cubes or pics of the box? 2.1 is to little for that sub so that it plays the low lows best, Id say 2.6,2.7 is where is at and ported, making a hole in a box is not ported, it's a little worse than a nail on your tyre.

Your amp is just not 0.5 ohm stable, don't keep trying as you may damage it. Also no need to wire at 0.5 the sub is 2000W and the amp can source 3000W at 2 ohm. If you are not getting a lot from the sub try getting better electrical and a better enclosure design and set your gains correctly.

If you have t/s parameters for the new version you could list them here or picture them, still, 2.5 net or something like that is too much for most 10" subs as it too much for some 12s. In fact most manufacturers try over time to design subs that work in smaller boxes.

This sub plats very peaky even in average sized boxes so for a single XFL-10 you should keep 1.0-1.5 cubic feet net and about 20 square inches of port area at 35Hz and 1500W. I would really like to know what people are recommending 2.5 cubic feet specially if overpowering 50% above rated.

There are some bass knob replacements that just work as a signal processor would BEFORE the amp but results would not be the same, I would just talk to NVX and they will tell you what will work or source you the component. IDK, you could also contact the buyer of the car, maybe he still has it, who knows.

Yes that was the one to get (didn't know about the V2) will be much better off than with a full bridge, except for the size, let us know how you got it done, don't know if a seat lift can help making room for all the stuff you want there and the amp. Also hopefully you don't get another D1 sub by itself and save yourself from some headaches.

Sub boxes go in the trunk generally in a sedan, that's the best possible location for it.

Let us know what you chose and how it went, I have to say that I held in better regard those JP amps, there's also widespread reports of insane overheating with some of them.

Well let's say the amp rack is not a primary concern, your box size is so large you could two of those subs instead of one to be on spec. by not having a port you are missing half the output your sub potentially have. The hole you did is just making the sub to work almost like there was no enclosure.

I don't know about that 0.5 ohm warranty in an amp that clearly can't do 0.67 or an amp two ohm stable that blows on 2.66 or why you get a D1 sub only to get to need amps supporting odd impedances... I don't know if you are cursed somehow or just your component selection process needs to improve, i don't know if you see it. Anyways luck with your next purchase.

For 1.75 net a 4" port needs to be 14.7" long for a 33Hz tuning. Said that a 4" round port is barely large enough for 600W power if you push more power you may get port noise. Ideally a slot port with 20 square inches of port area is needed to get the best out of the sub in a ported enclosure.

That box is too big for the sub and with that hole you made it just makes it worse, you could damage the suspension of your sub if you push a lot of power to it, also placing the amp on the box can damage the amp due to vibration. You make an amp rack to place your amp away from vibration.

In this test the JP23 V2 it couldn't take 0.67: https://youtu.be/WUBkIoQsywk?t=166 Anyways sure you can use the HD3K 2ohm but if you don't know what went wrong with your m28k using another full bridge amp might be not a great idea. I'd be curious if JP honors that warranty and it's confirmed is their fault or what they tell you.

First determine the box size you are comfortable with I say the 1.75 net is fine given your amp is 1000W RMS and your sub is 600W RMS, large box size means you will need to run it a little more carefully and set your subsonic filter higher.

The JP23v2 is not 0.5 ohm stable so I would forget about warranty, I say get whatever amp that is 0.5 ohm stable, those full bridge amps like taramps really don't like being wired below their minimum stable. Take care man you are already two amps out. The Taramps Smart 3 BASS is 0.5 ohm stable but voltage at power terminals need to be 12.5 to 15V at all times NO exceptions, not even for a second.

Let me know what vehicle are you using and why did you pick a shallow mount sub and not a regular one.

Your box is completely wrong and the reason it doesn't get that loud, go to sundown website and use one of their box designs or if the dimensions are not suitable ask here for one that is. Also you may need an aftermarket alternator if you use the sub continuously at loud level.

If you use a net volume of 2 cubic feet net and a 10 port it would need to be 96" long to be tuned to 32 hz. Regardless of if it will work or not how is it going to fit that and how is going to look, just by looking at that you can see that using the 10" pipe is not going to work very well.

The correct port area is what the manufacturer tells you, the port area for 35Hz will be the same as for 31,32 or whatever you pick in the lower 30s. If you are doing way more power or your box is way off the size the manufacturer tells you then you need modeling software to get port area right but otherwise follow the manufacturer suggestion, that tritricum calculator is either wrong or you are not using it right, I do not recommend using any calculators, use modeling software. Use 30-35 square inches of port area, no more or you are going to get a ridiculously long port that is going to make the box gigantic and your port will suffer quarter wave resonances and inefficiency due to the excessive length.

Model shows you need 80-90 square inches ON 3k for this sub but no more, if you do 100 square inches should cover you well enough at 8 cubic feet net volume. If you are not getting the expected performance look at your electrical system and setup your gains correctly, your tone controls and crossover points in your system should be all checked to be good.

You post an audio clip? I would be more interested in video!

To the strapped pair you can use any final load of 2 ohm including 2 D2 subs. Or even run one sub to each amp at 1 ohm final.

You can absolutely run the strapped amps to coils in series sub is just that if you play a continuous sinewave of 4000W+ watts the sub may not like it a lot,

You reported 2 ohm final load in your OP, I guess you had bad contact in one of the coils and therefore the 2 ohm. But now redoing the connections you report below one ohm final load as it should and that's good progress. Congrats!

As the suspension looses they will play lower better but also make them hit mechanical limits easier, give them a week or two to know what they actually do. Maybe I should look at the models for both of your subs, I will get back to you. The port to do depends very much on your situation, all port types can work, a non turning kerfed slot port can be all you need if you can keep a low area ratio, flared round port are best used in extreme SPL as well as extreme sound quality setups.