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galacticmonkey
12-31-2009, 06:18 PM
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?

NoCoSPL
12-31-2009, 06:20 PM
Positioning will be a tough one i think. Possibly build box to slide forward and back to acheive maximum?

stevew007
12-31-2009, 06:25 PM
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
12-31-2009, 06:29 PM
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
12-31-2009, 06:29 PM
I was thinking bandpass would be the way. Never done a 6th order though. Always done 4th and had great results.

T3mpest
12-31-2009, 06:32 PM
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
12-31-2009, 06:33 PM
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
12-31-2009, 06:33 PM
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
12-31-2009, 06:35 PM
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 ***

EDIT: Wasn't loud to me.

galacticmonkey
12-31-2009, 06:37 PM
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
12-31-2009, 06:38 PM
Also, its a 1990 Astro.

Villeza1
12-31-2009, 06:44 PM
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
12-31-2009, 06:46 PM
how bout 2 15's and 20 cubes with 1200 square inches of port tuned to the vehicals frequency

80

galacticmonkey
12-31-2009, 06:50 PM
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)

http://i48.tinypic.com/5lzzp3.png

http://i47.tinypic.com/14sdrig.png

spltuscon
12-31-2009, 08:52 PM
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

stevew007
12-31-2009, 10:27 PM
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

yes and i think he also did a bassrace bandpass

galacticmonkey
01-01-2010, 11:03 PM
Eventually I'm going to build it as a huge music bandpass. Down the road eventually I would like to see it doing a 164-165 on music.

I was actually thinking of trying a SS NW build.

Villeza1
01-01-2010, 11:05 PM
Eventually I'm going to build it as a huge music bandpass. Down the road eventually I would like to see it doing a 164-165 on music.

I was actually thinking of trying a SS NW build.

Jesus Christ! I'd love to see that.

galacticmonkey
01-02-2010, 12:05 AM
Ill get there eventually.

Toxic Tuan
01-02-2010, 01:30 PM
Eventually I'm going to build it as a huge music bandpass. Down the road eventually I would like to see it doing a 164-165 on music.

I was actually thinking of trying a SS NW build.

The equipment it's going to take to do a 164-165 will require a full wall. Even that is tough.

For SS NW, I don't know anybody competitor to my knowledge running a Band Pass design. I help built a SSNW car that has 165 db in it. It was DQ-ed at 06 finals due to political stuff.

Tuan

galacticmonkey
01-02-2010, 02:26 PM
For the 164-165 it would definately be a wall. Probably something like 12-16 12s or 8-12 15s with like 40,000-60,000rms.

But right now Im thinking either the 2 15s in a SS NW box, the 2 15s in a full wall box, or just get like 12 Hifonics Hfi 12s and do a music build. See if I can break like a 153 or something with $200 in speakers.