metalhead needs a ported box design for a 12" Pioneer TS-W3003D4

[2RZ-FE 10+ year member]

I will try and sneak my box to my car later tonight and check things out. Raining off and on. I have to walk like 120 ft to my car carrying the thing.

 

[shredder2]

Op... after all this, you got a graduate course in Torres and making changes to tuning... I sure hope it's worth all the headache and sounds good.

 

[2RZ-FE 10+ year member]

Got the box in. Sub is 4" from the back centered not near a loading wall. Not much was happening at first so messed with the rca's at the deck and amp. Now it pounds like a thing a beauty. Maybe they weren't pushed in all the way I don't know. Highs were also too loud so lowered the gain. There is a big difference in volume from 21 to 26 on this deck too I never went past 21/22. Going to swap the rca's for better ones and adjust the gains properly tomorrow. Thanks for the help everyone.

 

[Boomin_tahoe 5,000+ posts]

So the RCA's were the issue....

 

[2RZ-FE 10+ year member]

Yeah. Cheap 4000 series stingers. I still have some knu krystals lying around. Just hate how tight they grab the rca jacks...

 

[2RZ-FE 10+ year member]

Played some NWA seems to handle the lows ok with this box...

 

[THATpurpleKUSH 5,000+ posts]

I've done more than a few this year... lol... I don't post EVERY box I do... but you're right... I have put up pics of mostly slot ports... those big SUV boxes are easy to do and when built by someone else its usually the owners preference... and the price of a pair of 4", 1 or 2 6" or an 8-10" aero usually scares em off as well... PVC works ok... but folks dont like the look... IDK... I'm a wood/screws and glue guy... I like it basic. I even cheap out on carpet settling on Krylon most the time, hey... as long as it sounds right and pounds I'm happy

I keep mine as basic as possible mostly for the sake of keeping costs down because it's meant to be profitable when resold. Carpet absorbs sound waves so I stick to paint, stain or bare wood.

Who uses round ports anymore tho?!

99% of my box builds are round port designs. They are simple and easy to design around most of the time and usually weigh less because they use less wood. I'm no expert on fluid dynamics but there's a reason why round shapes are used for airflow- exhaust piping, air hoses etc. Round flows the most efficiently, not rectangles, octagons, triangles, hexagons etc.

 

[2RZ-FE 10+ year member]

Still losing bass at times today. It isn't the rca's as it did this with both sets. My deck was grounded to the chassis behind the dash so I grounded through the factory harness instead. Not even sure where the chassis ground even leads to back there. Haven't had a chance to check it out yet to see if it was resolved. Could two separate amp grounds 14" apart be the issue? Where is a good grounding spot in a trunk, amps are placed right behind the seat backs that fold down?

 

[Jeffdachef 5,000+ posts]

I keep mine as basic as possible mostly for the sake of keeping costs down because it's meant to be profitable when resold. Carpet absorbs sound waves so I stick to paint, stain or bare wood.




99% of my box builds are round port designs. They are simple and easy to design around most of the time and usually weigh less because they use less wood. I'm no expert on fluid dynamics but there's a reason why round shapes are used for airflow- exhaust piping, air hoses etc. Round flows the most efficiently, not rectangles, octagons, triangles, hexagons etc.

I explained this in another thread.

Mainly try to get enough port area to not get port noise and then get the proper tuning. As for which port is better, the more square/circle a port becomes, the more efficient it is as in it'll do its job without seeing much port noise compared to lets say a long skinny port aka all those prefab boxes with 1.5 inch x 13 skinny ports. The way you know this is by surface area of a rectangular prism basically The more surface area means the more air friction means less efficiency.
A=2(wl+hl+hw)

lets say you have a length of 20 and lets shoot for a port area of lets say 64 sq inches

One port will have 4 width x 16 height A=2(4*20+16*20+4*16) Surface Area = 928

one port will have 8 width x 8 height A=2(8*20+8*20+8*8) Surface area = 768

So as you can see the more square a port becomes, the more efficient due to less wood surface area that air has to travel through meaning you can get by with a lot less port area than a long skinny port.

here's a calculator for you to play around.

https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=surface+area+of+a+rectangular+prism&*

How about a round or aeroport you ask?

simple same length 20 and same sq inches 64

area of a circle is pi x radius ^2 so to reverse that 64/ 3.14 = 20.3. square root of 20.3 = 4.51 inch diameter round port.

Now you find the surface area of a cylinder. which is A=2(3.14)rh+2(3.14)r2

Plug that in to here https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=cylinder+surface+area&*

and you will see that with a 4.51 diameter round port, the surface area = 694.54 which is less than the square port aka more efficient.

to answer question #1 it actually depends on the subwoofer and vehicle its in. Every vehicle will sound different and require a different type of tuning. Some will play rock just fine tuned at 32hz. Others will require 40hz tuning so its best to test out the cabin gain of each vehicle to see what frequency you peak at.

question number 2, There is no "hidden chamber" ported box. There are 4th order bandpass and there are Aperiodic Bi-chamber (ABC) ported boxes.

4th order is a sealed and a ported combined good low end extension and good output if you have a higher ratio of ported to sealed only works with woofers that are good in sealed boxes aka Efficiency Bandwidth Product (EBP) of 55 or less here is a calculator, find your sub's TS parameters and plug it in Efficiency Bandwidth Product Calculators - EBP, Speaker Resonance Frequency, Speaker Electrical

Aperiodic bi chamber boxes are meant to tame peaky woofers for a flatter response.

Yup gramps there's waaaay more to subwoofers and enclosures than you'll ever know. What you know only scratches the surface.

mostly sound the same but will help slightly with airflow Its always recommended. Gains are very very tiny but gains are still gains.

 

[2RZ-FE 10+ year member]

No issues so far using the harness ground instead of the chassis as the deck ground. Maybe my imagination but sounds cleaner too

 

[2RZ-FE 10+ year member]

Made a new box, 1.5 cf net with an external port of 3”x6” firing toward the rear so I can load it off a wall. This box is the recommended one in the manual tuned to about 39. That’s what I want. Should I stick with that or use two 3” ports again? I Have a new amp as well a JBL GTR-1001 No sub sonic filter and I am being conservative with the gain

 

[2RZ-FE 10+ year member]

Scrapped the 3" port so ran it sealed until I tracked down some 4" PVC. Cut a piece 14.5" long for 36hz. The reason I scrapped the other box is to use an external port and have it fire off a wall. It will fire off that small section of wall between the taillight and wheel well. Wanted rear fire but don't have 18" or so in front of the box my amps are right behind it. 

 

[THATpurpleKUSH 5,000+ posts]

If you buy an aeroport you can mount the flare to the box and easily swap out different port lengths. Not sure how easy your method is or how you're attaching the port tube.

 

[2RZ-FE 10+ year member]

I can cut it down to 40hz and from there use a coupler and some pipe to tune lower. I scuffed the tube 2" from the end to remove the sheen. Made the hole in the box slightly larger so I can seal around it in and out with a saw dust and wood glue mixture. It's not going anywhere. 

Not sure how low Ice Cube plays but it played it no problem. No SSF either. Cannibal Corpse sounded fine too. Should I go 40hz for Cannibal Corpse?

 

[THATpurpleKUSH 5,000+ posts]

You should seal the pipe in the box with 2 part epoxy glue and latex caulk on the inside. 

Not sure what a Cannibal Corpse is so I can't tell you what to tune for. You only need a ssf if you're playing a good 7-10hz or more below tuning.