Box design 'trouble' - 2x12" 4th order bandpass

[Ozzt]

Hi all! new to this forum and was wondering if someone could be so kind and help me out with a box design.

The subwoofers are 2x12" Ground Zero Hydrogen 30X rated to 800wrms each
specs:
http://www.ground-zero-audio.com/components/com_jshopping/files/demo_products/GZHW_30X.pdf

or
http://www.ground-zero-audio.com/components/com_jshopping/files/demo_products/manual_gzhw.

and the amp im using is a Kicker 11zx2500.1 rated to 2500wrms@2ohms, but benched to a little over 2650.

subwoofers is wired to 2ohms

Both Power and Grounds are 53mm2 OFC cables, and i use 300A fuses. I have an extra 95ah AGM battery in the back, which is for the amps only.

I got a box design from the shop where i bought the subwoofers, but im not sure its optimal... I have already made the box. put it in the car, and wired it up, for some songs the box is pure magic and plays perfect, but on others the bass is 'grumsy' and plays when it's not supposed to. i have played around with the integrated crossovers on both the amp and on the headunit, but since I can never get it right I think the box is the problem

(Measurements are for 19mm mdf, but i made it in 22mm)
The ports go up through the rear deck

Could someone test this in winisd, bassbox 6 pro or something and check if its optimal? I would be grateful

the rest of my system consists of a Rockford fosgate T165-S component system wired up to a Rockford Fosgate p2002 amp (old model) and the headunit is an Alpine CDE-178bt

the car is a Mitsubishi Galant 1997 model, but I have changed almost everything (interior and exterior) to 2003 avance.

Any other recommendations for changes in the system, critique or other thoughts?

[Deeznutz]

Looks like a 1:1 ratio enclosure.

What songs are you playing when the bass response is "grumsy and plays when it's not supposed to" ?

That amp might be too powerful for the subs and you might be getting alot of feedback. The same thing happened to me

with the GMC build. Some songs play fine at 3/4 turn of the ext. bass knob, i.e. bass music.

While others songs sound way too boomy and the knob has to be turned to about 1/2, some club/dance/rock music. This seems to tone down

this boominess.

You mentioned you adjusted the crossovers, but that should not make a difference on the enclosure.

I have read that the bandpass enclosure will filter out unwanted frequencies, and will only let the "band-pass" play through.

Turn down the amp on the "grumsy" songs and see it that changes the unwanted output.

The bass knob is your friend.

-Frank

[Ozzt]

I dont know if 'grumsy' is the right word... more like imprecisely.
Im using spotify on mobile and use bluetooth to connect it to the HU. When Im playing 'gangsta'/rap music its mostly good, but when playing club/party/rock music its sometimes good, sometimes not.. I have tryed using the bass knob, but if i turn it down i get close to no bass, and the 'grumsy' is still there allthough its not so loud.
I know the crossovers dont do anything about the enclosure, but what I've been trying to do is to filter away the frequencies where the bass is bad, on some songs this works "OK" but on others again it doesnt.

when im alone in the car i mostly listen to rap, dubstep and such. but when I have passengers i listen to a wide variety of music, so if its possible i would like it to play good on all types of genres. allthough this is maybe not possible with a bandpass box? I have given ported or sealed enclosure a thought, but since my car is a sedan, and i like to have the bass in the car and not the trunk, i went for bandpass.

I know the amp may be overkill for the subs, but I heard these subs in particular could take a beating, and since i got the amp cheap from a private person (it wasn't used). I went for the bigger the better this time..
2500wrms/2 is 1250wrms, and the subs are 800wrms, Its a bit much, but not too much I think

sorry for bad english, im from norway so..

[rambronco]

Not as familiar with Bandpasses as with straight vented when it comes to port area, but if that was a ported box I would say the port area is very low, 2x4" = approx. 25 sq in. total box size of approx. 3.5 cu ft. Aero ports are a little more efficient than rectangular ports so lets just use 10-12 sg in. per cu ft, brings you in the range of 35-42 sq in. of port area. As mentioned not as familiar with the bandpass im sure someone will chime in, but possibly something to look at.

[Krakin]

Not as familiar with Bandpasses as with straight vented when it comes to port area, but if that was a ported box I would say the port area is very low, 2x4" = approx. 25 sq in. total box size of approx. 3.5 cu ft. Aero ports are a little more efficient than rectangular ports so lets just use 10-12 sg in. per cu ft, brings you in the range of 35-42 sq in. of port area. As mentioned not as familiar with the bandpass im sure someone will chime in, but possibly something to look at.

Never use the port per cubic foot rule. Use proven science instead.

[StreetMetalBen]

Not as familiar with Bandpasses as with straight vented when it comes to port area, but if that was a ported box I would say the port area is very low, 2x4" = approx. 25 sq in. total box size of approx. 3.5 cu ft. Aero ports are a little more efficient than rectangular ports so lets just use 10-12 sg in. per cu ft, brings you in the range of 35-42 sq in. of port area. As mentioned not as familiar with the bandpass im sure someone will chime in, but possibly something to look at.

Never use the port per cubic foot rule. Use proven science instead.

I must research this.... :-) Thank you!