Guys I am looking to build my first 4th order enclosure. I have always ran my subs in ported boxes but since I have 6 SP4's now I want to maximize them. Any of you guys out there running the SP4 15's in a 4th order and if so what type of numbers did you use as far as sealed/ported, cubes net and port area? I have max dimensions of 46W x 60D x 32H....Its in a Infiniti QX56 SUV on 2 Crossfire XS-8k's for power. I am doing mid 50's right now using 4 of the SP4's but the mid 50's I am doing are between 27hz and 33hz.

Edited April 5, 201510 yr by 95 south

You mean bandpass? That wouldn't be optimizing anything other than the lack of a reasonable frequency response.

If anyone offers you a ratiohey are an idiot...

Just do a flatwall...

Flat wall will maximize, if by maximize you're meaning ease of getting loud. Think; how will restricting cone movement and heaping power on, make it easier to get loud? More stress on the equipment, more money in electrical, lose lose.

Yes I mean bandpass....I have 2 options right now. I can either run the 4 Sundown custom Nightshade V3 15's in a bandpass enclosure or I can do a bandpass from the B pillar with the 6 Sp4's I have. I really would like to run the SP4's since its more cone area and I wouldn't have to buy 2 more Sundown subs. I my SUV I cant do more than 4 subs in a flat wall.

The T/S parameters are suitable for a 4th order bandpass.  But, as a others have stated, there are a lot of trade-offs if you go this route.

 

Honestly, modeling both choices first (4th order vented and 4th order bandpass) with the power you will have will be the only way to tell you which would be louder.  BUT, pay close attention to the passband of the bandpass and see if it is worth it...

Hey thanks 95Honda....I will model both and see what's best. I just want to try a new setup outside of throwing boxes in my hatch like I have done forever. I do really well in SS 3/4 in comps but like the idea of rebuilding since this is my main hobby now....Again thanks

And as M5 said NO RATIOS to start with....

The trade-offs are nasty. As a design a BP surely has a place but is BY FAR the most misused alignment in car audio. Anyone whoever has built one with modelling is pretty much retarded.

^^^^.....lol....Yeah I have a friend that has one and it don't play anything below 33hz.....The upper notes are pretty strong but with 4 15's on a 7k he cant do anything more than a 148.3 on the meter.

And there are other web forums filled with morons building bandpass enclosures for all the wrong reasons. They have power like your friend and the results are loud, but could be way better if they had a rudimentary understanding of audio.

Pretty much more than 90% of BP designs are fucked up bad on car audio forums. Maybe higher. By fucked up I mean a pointless waste of wood.

It is also obvious who they are as they call BP enclosures 4th orders. A standard ported box is also a 4th order. Sort of tells us who has been leading you. Beware what you think you know from where that is as most of it is wrong.

No I understand what you are saying completely...So just to ask you...With my power and subs what would you build if you were doing it for demos and fun??

No I understand what you are saying completely...So just to ask you...With my power and subs what would you build if you were doing it for demos and fun??

Since you are asking me personally what I'd do I can answer. I'd never, ever, ever build a box for demos. I build a box to play music for me in the drivers seat. Could care less about anyone else and what they think of my system. If it satisfies me that is great. Now more importantly, in order to do this I'd model what I want and then build based on what that tells me. Of course I'd also do this WAY before buying anything.

I despise bloated bass. Not that I don't like bass, but being a bass & guitar that part should be obvious. I want it to accurately reproduce the recordings I listen to and nothing more.

And if I drove a QX56 there is no way in hell I'd ever recommend a 4th order BP. No reason I can think of that it would make sense for.

Ok gotcha.....Thanks for the feedback. I will take a hard look at my goals for the next setup and keep you guys posted on what I come up with. I agree with you as far as it sounding good and being able to reproduce sound. My mids and high stage sounds really nice right now I was just brainstorming about the low end...

Bass is super easy the front stage is what is hard. I'd spend more on the fronts thanthe rears