Astro SPL?

[galacticmonkey 5,000+ posts]

I just got a 1990 Astro and thinking of trying a fartbox. Ive done a ton of loud music builds, but never designed or built an SPL box.

As for equipment, Ill most likely be borrowing 2 custom BTL 15s. As for amps, Ill be testing some amps for a friend of mine so Ill have up to around 7,000rms for each speaker.

Now the tricky part, the box. I have the whole van for airspace, but just dont know what kind of design would work. Should I just go ported? Or a huge bandpass? I really dont have the first clue when it comes to designing a strictly burp box.

I could change out the subs for a couple lower end 12s or 15s probably... Just not really sure of what kind of equipment or box type to go with. Id like to stick with the 2 15s, but if they wont work, like I said Im open to other options.

Ideas?

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[NoCoSPL 10+ year member]

Positioning will be a tough one i think. Possibly build box to slide forward and back to acheive maximum?

 

[stevew007 10+ year member]

do a bandpass at the b-pillar,port on drivers, tuned into the 60s that should get you close to or into the 160's

 

[Villeza1 10+ year member]

do a bandpass at the b-pillar,port on drivers, tuned into the 60s that should get you close to or into the 160's

160's with 2 15's would be crazy...but will a bandpass be able to produce that?

 

[galacticmonkey 5,000+ posts]

I was thinking bandpass would be the way. Never done a 6th order though. Always done 4th and had great results.

 

[T3mpest 10+ year member]

First thing to do is figure out where the astro peaks at when you reinforce the boundary that will be your wall. Put in a sheet of mdf to simulate your new back wall boundary, put a sealed sub in the vehicle and compare each frequency to what winisd says you should get. The highest difference is going to be close to your peak frequency once you get the actual subs in. Assuming you can keep everything from flexing and messing with it, but obviously you'll have to test the BTL's eventually anyway and possibly retune slightly. That method will get you very close though. Anyway I vote for a tapped horn enclosure if you want to be VERY cutting edge lol.

 

[80INCHES 5,000+ posts]

do a bandpass at the b-pillar,port on drivers, tuned into the 60s that should get you close to or into the 160's

u cant do that ...ported boxes yea tune in the low 60's ...but that also depends on wat yr the astro is

80

 

[basscort2009 5,000+ posts]

how many world champs have u seen use bandpass? best SPL box is boring old slot port. 4:1 length to width ratio for spl. 20-30 inches of port per cube rather than the 12-16 for daily. build box on the small side if you throw more. power, will take more to get loud but will stay more efficient and handle more power doing that. try to make the port NOT L off if you can for better results also. theres tons of things that go into an spl box. hope this helps man

 

[Villeza1 10+ year member]

I was thinking bandpass would be the way. Never done a 6th order though. Always done 4th and had great results.

Yea, I've heard a 6th order bandpass b4 and was not impressed. 4 15's walled with 6k...sounded like ass

EDIT: Wasn't loud to me.

 

[galacticmonkey 5,000+ posts]

Alot of World Champs have bandpasses actually.

Anyway, I see lots of Astros with SPL walls with huge ports. Like Carlos' Astro with 4 BTL 18s... He just has the subs then the biggest port possible. But being that I only have 2 15s.... Eh.

What about like 12 cheap Hifonics 12s? Worst case if it doesnt work I can always buy more and do a loud music car.

 

[galacticmonkey 5,000+ posts]

Also, its a 1990 Astro.

 

[Villeza1 10+ year member]

Alot of World Champs have bandpasses actually.
Anyway, I see lots of Astros with SPL walls with huge ports. Like Carlos' Astro with 4 BTL 18s... He just has the subs then the biggest port possible. But being that I only have 2 15s.... Eh.

What about like 12 cheap Hifonics 12s? Worst case if it doesnt work I can always buy more and do a loud music car.

Mmm, idk. I'd say go for it, it'll be another experience to try a 6th order bandpass.

What about 24 alpine type r's 12's!? Lol I'd like to see that!

 

[80INCHES 5,000+ posts]

how bout 2 15's and 20 cubes with 1200 square inches of port tuned to the vehicals frequency

80

 

[galacticmonkey 5,000+ posts]

If I were to do a 4th order, I would think maybe something like this? Just have the shell built as big as possible, then build 2 seperate sealed boxes. Put them in the corner, then pannel off the side that I think would create problems so its a smooth baffle all the way across, but the subs only see the little airspace they are in. (Pic 1)

Or would it be better to have just the boxes on the side and a gap to the side of them? (Pic 2)

 

[spltuscon 10+ year member]

Build it as a regular slot ported No-wall at the b-pillar. Subs to the passenger side port to drivers side. Pete S. did very good numbers with a pair of fifteens in a 94 astro in DB Drag in 2008 with this layout. He did a whole build thread on it here http://audioforum.termpro.com/topic/3/6879.html