Off to a good start but need help

[Weldwithwelders]

Off to a good start on my first serious system the end goal in mind is a comp level system but in a daily driver with practicality put first it's my only daily driver end result will be sq biased but have the ability to turn it up till I say that's too loud instead of reaching system limits

I'm running alpine ilx 650 into a dayton 4x8 dsp
Front is a 3 way active setup 6.5 inch infinity kappas with the kappa 20 mx midrange add ons the mid bass are being driven by a kicker 650.4 class ab (only two ch driven)
Hi mids and tweets are fed by a hertz audio hcpd4

2 alpine s series 12 inch subs driven by a pdx 1000.1
Under rear seat in a pre built(poorly) box which needs help or a new one altogether it's hard to tell if it's distortion or the box causing issues uvebliwn it apart twice

The hi mids and tweets no complaints except the past weeder (pillar mount) is dominant no matter what and I've had help from an experienced and trusted car audio guy

The mid bass have an issue around 120 hz that can't be eq d out and they don't seem to stand up to info it's rms rating

The subs seem like they should be louder than they are I got double the power than I've ever had and I'm not impressed but the box was put together poorly I've been having to fix rattling panels cracking panels and split the box at one time

Main issue is my subs im at the limit for box size but got to figure out how to keep one together I'm gonna build my own for the first time I'm running type s right now but I want the box to be able to handle some type r s if I feel the need for more that being said there is not alot of room for box bracing without hitting the driver all I can think of is a double baffle and some sort of dowel pin setup Tgat locks the panels together

[BigAl205]

What vehicle is it in?

[jrwalte]

The mid bass have an issue around 120 hz that can't be eq d out and they don't seem to stand up to info it's rms rating

Most tend to have issues with mid-bass in doors. It is the bane of car audio! But how have you prepared your doors? They need to be well deadened and sealed between the front and back of speaker. There should be no gaps anywhere in the door that can get into your vehicle. But even then, you will still have dips in a car. I dealt with mine by lowering the output of all my speakers to match my 125hz dip. But some systems won't have enough output afterward or the dip is just too deep. In those cases, you just have to live with it.

The subs seem like they should be louder than they are I got double the power than I've ever had and I'm not impressed but the box was put together poorly I've been having to fix rattling panels cracking panels and split the box at one time

If the sub box has cracked, it is worthless and needs replaced. You aren't going to get any decent output from a cracked box.

[geolemon]

The tweeter being dominant really shouldn't be tough to dial back - there's more than one way to skin a cat as they say, but often times component sets come with a passive crossover that allows you to attenuate the tweeter. With resistors you can build an L-pad to emulate what you had with the stock crossover, if you've ditched it, or just need it.

However, with your Dayton DSP, you should be able to simply EQ them down. With the 120 Hz bass null, that's sort of common - it's interior dimension dependent, but most people experience that more around 70hz and 200hz - yours happens to be in between that - is there somewhere else that you also have a null?

But also, to build on what jrwalte said - you have to think about how speakers in general work, and respect that at least at the most fundamental basic way, or all bets are off.

Picture a speaker cone moving in and out - when it moves out, it pressurizes the air in front of the cone. When it moves in, it de-pressurizes the air in front of the cone. And I'm sure you can imagine the exact opposite happens on the back-side of the cone - inherently. The sound from the back of the cone is 180 degrees out of phase with the sound from the front of the cone. Accordingly, if you didn't have the speaker in a baffle or enclosure, the high-pressure energy would simply dissipate into the low-pressure zone on the opposite side of the cone, and you'd be left with basically no sound.

So...

Midbass. Those doors, and specifically the inner door structure where the speakers are actually mounted:
At minimum, you want that surface to be hole-free, so no rear-of-cone energy can escape and cancel out front-of-cone energy. Waves get bigger as your frequencies get lower, so you'll lose bass more than you'll lose midrange, but it's best to ensure you've treated your doors properly - by whatever means close up all the holes and gaps. Some people use sheet metal and damping material, if your gaps aren't too large you might be able to get away with just damping material - some people go nuts and build enclosures... that's very hard to do, so start with just making the door surface a good "baffle".

Sub box. You need one. And it needs to work well. Again, the lower you go the more cancellation you get, so if it's sealed, it needs to be SEALED.
But guess what? If it's vented, it needs to be sealed even MORE! That port isn't a hole, it's a specifically sized mass of air, and it is set into an in-and-out motion nearly (but not quite) in phase with the cone - that's why vented boxes are louder. It is like extra cone area... and that extra cone area inflicts MORE pressure inside the box, not less.

If it's just a crack in the box that's not well sealed, I'd expect some whistling or chuffing or farting sounds, but it can also sound like clunking. If it's a big gap, or an improperly sized vent - you could bottom the sub and not get much bass. But since you have "more power than you've ever had", I suspect that's not the issue.

If you aren't impressed with the bass from your box, it could be many things:
If you have a "vented box sub" (low Qts and/or high Fs) in a sealed box, it's bound to be overdamped (dull) and not hit as low as you want.
If you have a "sealed box sub" (high Qts and/or uber-low Fs) in a vented box, it could be uncontrolled and sloppy, and not efficient - and possibly an odd shape frequency response.
If you have a vented box at all, you could have an odd shape frequency response, if not well designed.

Hope that helps, all those areas are worth revisiting and thinking about.