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4th order blow-through build help, 6 18's


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Hey man, I built the truck in the video I am including in your thread. Many people told me not to do subs up with port forward, but it honestly worked out great in this truck. I won't lie one bit about one aspect....the truck falls flat on it's face if the windows are up and doors are shut...only does a 52-53 from 32-47 Hz.....as soon as you roll the windows down though, this thing instantly jumps to a 56- 57......it's crazy as hell.

All of that being said, I went with right around 2.8 cubes net sealed per woofer and then the ported chamber is right around 22 cubes net with 310 square inches of port. Obviously this is not the biggest ratio, but it worked out great for this truck. With 4th order alignments, it's safe to say most folks go with a 2:1 ratio (ported to sealed). It would also be my suggestion to stay somewhere between 14-18 square inches of port per ported cube and a tuning of 46-51 Hz. The best advice anyone can give you on the ported chamber is to start with the largest port possible and then start testing/shrinking/testing/shrinking from there until you begin to lose Db's.

I would also encourage you to read through this thread on CACO for further information. The thread is super long, but there's lots of great information in there about 4th order alignments.

http://www.caraudioc...quiet-them.html

Was looking at that thread and another question came up.. Do you think I would be just as loud if not louder doing 4 OA 18's with a 3:1 ratio instead of 6 with a 2:1? If so, that would be a lot easier to build and would save me a little cash.

Sorry for not getting to your question any sooner.....I believe the answer would potentially be yes. There are absolutely situations where less is definitely more. If you have adequate room for all 6 to get the air space and port area you'll need then I would definitely do 6. However if there was any doubt of proper fittment, then you are on point with dropping to 4 woofers.

As far as air space for those woofers is concerned, there is practically no chance I would ever do 4 cubes sealed for an 18. I'm hopeful 412 CVX will shed some light on his recommendation, because most everyone running 18's in a 4th will be between 2-3 cubes sealed net per sub and will utilize somewhere between a 2:1 and 3:1 ratio for the ported chamber. I would be careful with port area as well because too much port will not allow for the ported chamber to pressurize/load correctly. The CACO thread talks about starting at 1/2 the amount of cone area (in square inches) that will be used in the build. As long as you stick to doing somewhere between 14-18 square inches of port per ported cube, I think this build will absolutely achieve the results you are looking for.

1999 2 Door Chevy Tahoe 5.7L V8

K&N Cold Air Intake

Kenwood KDC-BT555U

1 Clarion EQS746 Equalizer

1 Clarion MCD360 Crossover

4 Incriminator Audio 1st Gen Warden 18's - 4th Order Bandpass Wall

4 Incriminator Audio 40.1s

8 PRV Audio 8MB450 8" Mid-Range Drivers

8 PRV Audio 6MB200 6" Mid-Range Drivers

1 Stetsom 3K3ES

8 PRV Audio TW350Ti Titanium Bullet Super Tweeter

1 NVX JAD800.4

2 XS Power XP2000s

8 XS Power XP3000s

10 sets of Team Project DB BA60 Battery Terminals

3 Mechman 270 amp alternators

GETTIN LOUDER DAILY!

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I would think 6 15's in a 3:1 ratio would be the best option. But like you said, port area is a pretty key factor. When you get the numbers for me, i'll make sure to incorporate the interchangeable port into the design. i'll even throw in a couple of different port area/tuning combinations.

Just say no to Ground Pounder Customs.

More box builds

some cars do over 170db with one sub, so clearly my two 12"s can do that in my car, with my knowledge too! look out bitches!

I'm with captain stupid.

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  • 2 weeks later...

I would think 6 15's in a 3:1 ratio would be the best option. But like you said, port area is a pretty key factor. When you get the numbers for me, i'll make sure to incorporate the interchangeable port into the design. i'll even throw in a couple of different port area/tuning combinations.

Hey man, I built the truck in the video I am including in your thread. Many people told me not to do subs up with port forward, but it honestly worked out great in this truck. I won't lie one bit about one aspect....the truck falls flat on it's face if the windows are up and doors are shut...only does a 52-53 from 32-47 Hz.....as soon as you roll the windows down though, this thing instantly jumps to a 56- 57......it's crazy as hell.

All of that being said, I went with right around 2.8 cubes net sealed per woofer and then the ported chamber is right around 22 cubes net with 310 square inches of port. Obviously this is not the biggest ratio, but it worked out great for this truck. With 4th order alignments, it's safe to say most folks go with a 2:1 ratio (ported to sealed). It would also be my suggestion to stay somewhere between 14-18 square inches of port per ported cube and a tuning of 46-51 Hz. The best advice anyone can give you on the ported chamber is to start with the largest port possible and then start testing/shrinking/testing/shrinking from there until you begin to lose Db's.

I would also encourage you to read through this thread on CACO for further information. The thread is super long, but there's lots of great information in there about 4th order alignments.

http://www.caraudioc...quiet-them.html

Was looking at that thread and another question came up.. Do you think I would be just as loud if not louder doing 4 OA 18's with a 3:1 ratio instead of 6 with a 2:1? If so, that would be a lot easier to build and would save me a little cash.

Sorry for not getting to your question any sooner.....I believe the answer would potentially be yes. There are absolutely situations where less is definitely more. If you have adequate room for all 6 to get the air space and port area you'll need then I would definitely do 6. However if there was any doubt of proper fittment, then you are on point with dropping to 4 woofers.

As far as air space for those woofers is concerned, there is practically no chance I would ever do 4 cubes sealed for an 18. I'm hopeful 412 CVX will shed some light on his recommendation, because most everyone running 18's in a 4th will be between 2-3 cubes sealed net per sub and will utilize somewhere between a 2:1 and 3:1 ratio for the ported chamber. I would be careful with port area as well because too much port will not allow for the ported chamber to pressurize/load correctly. The CACO thread talks about starting at 1/2 the amount of cone area (in square inches) that will be used in the build. As long as you stick to doing somewhere between 14-18 square inches of port per ported cube, I think this build will absolutely achieve the results you are looking for.

Sorry for the late reply, I've been super busy. But My max dimesions are 50" wide, 38" tall, and as deep as I need. I have an 8' bed lol. But those dimensions would be pushing it. But with the obsidians, what I've heard, is 3 cu. ft per sub sealed with a 2:1 ratio. If one of you could help me with the design that would be greatly appreciated. For the port, I'd like it to be a rectangle where the rear window would normally be. Thanks for everything!

Audio Build

Ride: 2002 Chevy Blazer 4 door

Head Unit: Pioneer deh-80prs

Subs: 4 DC Level 3 15's in a 4th order wall designed by Trent Choate and Jeff Smith

Subs Amp: AQ 3500.1 at wired at .5 (soon to be 2)

Mids/Highs Amp: Skar 85.4

Mids/Highs: Skar components

Electrical: Mechman 270 amp alt, 2 runs of Knu 0 gauge, XS Power d3400, 2 Deka Group 9a31

Build log : http://www.stevemeadedesigns.com/board/topic/167658-indianabasshead-blazer-dc-audio-4th-order-wall-build/


Perfomance Build

2003 Nissan 350z

Greddy Twin Turbo, 3" Test pipes with Borla high-flow cats, Crawford Performance Plenum, Greddy E-manage Ultimate ECU

Exedy Racing Clutch, Built Motor by Racing Innovations

Greddy Over-fender aero kit (1 of 20 ever made), 19" Racing Hart r5 pro wheels
466rwhp


Bike

2008 Midnight Blue Kawasaki ZX-14

Stretched 8" and lowered, Brocks Sidewinder exhaust, Power Commander 5

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Also, box rise will be pretty awful with 6 woofers on 1 amp won't it? I've never really competed so box rise is pretty new to me. If they are wired at .66, what should I expect box rise to be with 6 of em?

Audio Build

Ride: 2002 Chevy Blazer 4 door

Head Unit: Pioneer deh-80prs

Subs: 4 DC Level 3 15's in a 4th order wall designed by Trent Choate and Jeff Smith

Subs Amp: AQ 3500.1 at wired at .5 (soon to be 2)

Mids/Highs Amp: Skar 85.4

Mids/Highs: Skar components

Electrical: Mechman 270 amp alt, 2 runs of Knu 0 gauge, XS Power d3400, 2 Deka Group 9a31

Build log : http://www.stevemeadedesigns.com/board/topic/167658-indianabasshead-blazer-dc-audio-4th-order-wall-build/


Perfomance Build

2003 Nissan 350z

Greddy Twin Turbo, 3" Test pipes with Borla high-flow cats, Crawford Performance Plenum, Greddy E-manage Ultimate ECU

Exedy Racing Clutch, Built Motor by Racing Innovations

Greddy Over-fender aero kit (1 of 20 ever made), 19" Racing Hart r5 pro wheels
466rwhp


Bike

2008 Midnight Blue Kawasaki ZX-14

Stretched 8" and lowered, Brocks Sidewinder exhaust, Power Commander 5

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Share on other sites

anyone?

Audio Build

Ride: 2002 Chevy Blazer 4 door

Head Unit: Pioneer deh-80prs

Subs: 4 DC Level 3 15's in a 4th order wall designed by Trent Choate and Jeff Smith

Subs Amp: AQ 3500.1 at wired at .5 (soon to be 2)

Mids/Highs Amp: Skar 85.4

Mids/Highs: Skar components

Electrical: Mechman 270 amp alt, 2 runs of Knu 0 gauge, XS Power d3400, 2 Deka Group 9a31

Build log : http://www.stevemeadedesigns.com/board/topic/167658-indianabasshead-blazer-dc-audio-4th-order-wall-build/


Perfomance Build

2003 Nissan 350z

Greddy Twin Turbo, 3" Test pipes with Borla high-flow cats, Crawford Performance Plenum, Greddy E-manage Ultimate ECU

Exedy Racing Clutch, Built Motor by Racing Innovations

Greddy Over-fender aero kit (1 of 20 ever made), 19" Racing Hart r5 pro wheels
466rwhp


Bike

2008 Midnight Blue Kawasaki ZX-14

Stretched 8" and lowered, Brocks Sidewinder exhaust, Power Commander 5

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Share on other sites

anyone?

Box rise is dependent on to many things to calculate it as having a lot of it without actually measuring it. However, yes, with all of those on one amp your amp will see the "box rise" of all the subs instead of dividing it up between lots of smaller amps.

For 15s I would say CVX is being pretty generious on box space. I would go no more than 2 cubes per sub. Especially if its one big chamber. You have to figure in one big chamber that each sub isnt going to divide the space up and say "okay I have 2.5 cubes of this because there is 15 cubes and 6 of us." Generally in a large common chamber as 6 subs would have you can make it a tad smaller. The 18s I would say to put them in roughly 3.5 max each. Then from there make your front chamber accordinly. The higher the ratio you are generally looking at a more peaky box with a smaller bandwidth, The smaller the ratio you are looking at more bandwidth but not as loud and peaky. Remember you can always stuff the rear chamber of the box with polly fil if you need it to have more space for a lower fs in the rear chamber.

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anyone?

Box rise is dependent on to many things to calculate it as having a lot of it without actually measuring it. However, yes, with all of those on one amp your amp will see the "box rise" of all the subs instead of dividing it up between lots of smaller amps.

For 15s I would say CVX is being pretty generious on box space. I would go no more than 2 cubes per sub. Especially if its one big chamber. You have to figure in one big chamber that each sub isnt going to divide the space up and say "okay I have 2.5 cubes of this because there is 15 cubes and 6 of us." Generally in a large common chamber as 6 subs would have you can make it a tad smaller. The 18s I would say to put them in roughly 3.5 max each. Then from there make your front chamber accordinly. The higher the ratio you are generally looking at a more peaky box with a smaller bandwidth, The smaller the ratio you are looking at more bandwidth but not as loud and peaky. Remember you can always stuff the rear chamber of the box with polly fil if you need it to have more space for a lower fs in the rear chamber.

Thanks for the info! I think I'm going to stick with the 18's if I can fit them. I would like to do around 3 cu. ft per. Would I be better off with all the woofers in an 18 cu ft box or 6 seperate 3 cu ft boxes? One big box would be much easier but is it as effective?

Audio Build

Ride: 2002 Chevy Blazer 4 door

Head Unit: Pioneer deh-80prs

Subs: 4 DC Level 3 15's in a 4th order wall designed by Trent Choate and Jeff Smith

Subs Amp: AQ 3500.1 at wired at .5 (soon to be 2)

Mids/Highs Amp: Skar 85.4

Mids/Highs: Skar components

Electrical: Mechman 270 amp alt, 2 runs of Knu 0 gauge, XS Power d3400, 2 Deka Group 9a31

Build log : http://www.stevemeadedesigns.com/board/topic/167658-indianabasshead-blazer-dc-audio-4th-order-wall-build/


Perfomance Build

2003 Nissan 350z

Greddy Twin Turbo, 3" Test pipes with Borla high-flow cats, Crawford Performance Plenum, Greddy E-manage Ultimate ECU

Exedy Racing Clutch, Built Motor by Racing Innovations

Greddy Over-fender aero kit (1 of 20 ever made), 19" Racing Hart r5 pro wheels
466rwhp


Bike

2008 Midnight Blue Kawasaki ZX-14

Stretched 8" and lowered, Brocks Sidewinder exhaust, Power Commander 5

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Like I said, the numbers I gave were rough guesstimates. Considering the amount of power he's giving them, it was probably best to err on the side of too much volume.

Just say no to Ground Pounder Customs.

More box builds

some cars do over 170db with one sub, so clearly my two 12"s can do that in my car, with my knowledge too! look out bitches!

I'm with captain stupid.

Link to comment
Share on other sites

anyone?

Box rise is dependent on to many things to calculate it as having a lot of it without actually measuring it. However, yes, with all of those on one amp your amp will see the "box rise" of all the subs instead of dividing it up between lots of smaller amps.

For 15s I would say CVX is being pretty generious on box space. I would go no more than 2 cubes per sub. Especially if its one big chamber. You have to figure in one big chamber that each sub isnt going to divide the space up and say "okay I have 2.5 cubes of this because there is 15 cubes and 6 of us." Generally in a large common chamber as 6 subs would have you can make it a tad smaller. The 18s I would say to put them in roughly 3.5 max each. Then from there make your front chamber accordinly. The higher the ratio you are generally looking at a more peaky box with a smaller bandwidth, The smaller the ratio you are looking at more bandwidth but not as loud and peaky. Remember you can always stuff the rear chamber of the box with polly fil if you need it to have more space for a lower fs in the rear chamber.

Thanks for the info! I think I'm going to stick with the 18's if I can fit them. I would like to do around 3 cu. ft per. Would I be better off with all the woofers in an 18 cu ft box or 6 seperate 3 cu ft boxes? One big box would be much easier but is it as effective?

Single box is fine. Only difference with a single box is like I said its not like each sub sees the exact space that its divided up to be. Also if one blows it will become a passive radiator and possible cause some unloading. But you would notice if one blew. I've been told by a friend that knows OA products pretty well that they like 2.75 cu ft ea and tune the front chamber between 48-54. Somewhere between a 2.5:1 to a 3:1 ratio if you can fit the higher ratio.

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