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View Full Version : 4th Order Bandpass Help



GearGuy2001
05-13-2009, 01:40 AM
How the heck do you design one, Ive looked and looked but I dont see anyone call out specifics of the box size and tuning.

I think my next box is going to be a single 15" RD Audio Alphamax off a 3000d in a bandpass with ports into the cabin, similar to shiznilti's lexus

I have room for 2-3 6" ports into the cabin if need be and below is a picture of my trunk.

http://img.photobucket.com/albums/v157/GearGuy2001/caraudio/suboxalmostdone031.jpg

Directly between the trunk and rear seats is my gas tank :verymad: so I think the best way is to run some pvc aero ports out of a bandpass box up through the old 6x9 holes in my rear lid (I dont have any rear speakers)

I PM'd 80 Inches but I figured Id post up and get other opinions also, Im open to designs but I want it to be loud. :D

Cabin_Pressure
05-13-2009, 02:03 AM
3cuft sealed rear chamber, 3cuft front chamber with (2) 6'' ports, starting with around 15'' lengths. Shorten to tune to your taste, most end up around 12'' in length on the ones i've built, but all interiors vary, so its easier to start long and shorten the port for tuning. If you need to go smaller with the box, reduce the same amount from each chamber to maintain an equal ratio between the front and rear chambers. I wouldn't go any lower than 2.5cuft per chamber for a 15'' sub. Just a suggestion from what has worked well for my bandpass builds.

80INCHES
05-13-2009, 10:45 AM
3cuft sealed rear chamber, 3cuft front chamber with (2) 6'' ports, starting with around 15'' lengths. Shorten to tune to your taste, most end up around 12'' in length on the ones i've built, but all interiors vary, so its easier to start long and shorten the port for tuning. If you need to go smaller with the box, reduce the same amount from each chamber to maintain an equal ratio between the front and rear chambers. I wouldn't go any lower than 2.5cuft per chamber for a 15'' sub. Just a suggestion from what has worked well for my bandpass builds.

actually he can...i would do no more than 2 cubes sealed for 1 15...and make the ported chamber as big as possible and tune the ported chamber to the frequency of his ride...he will still hit the lows regaurdless
but looking at ur trunk u have room for a 6th order....that would be nice and loud ...when done correctly
80

GearGuy2001
05-13-2009, 10:56 AM
actually he can...i would do no more than 2 cubes sealed for 1 15...and make the ported chamber as big as possible and tune the ported chamber to the frequency of his ride...he will still hit the lows regaurdless
but looking at ur trunk u have room for a 6th order....that would be nice and loud ...when done correctly
80

I sent you a PM back with my max dimensions. Are there any advantages/disadvantages of a 6th order?

Also with my 33hz box my car peaks at 44hz on the TL

80INCHES
05-13-2009, 11:42 AM
6th order is more efficient than 4th order boxes...depending on the design

80

GearGuy2001
05-13-2009, 11:50 AM
6th order is more efficient than 4th order boxes...depending on the design

80

Well if you could design something up based on my PM'd specs. 6th or 4th order, you choose (or both) Id be glad to send you a few $ via paypal.

vellocet
05-13-2009, 11:56 AM
Your trunk lay out kind of *****. I was wondering how you design these while playing with winisd the other day. Listening to some computer speakers with a 6th order that sounds good.
There any faqs around on designing these?

tez4life
05-13-2009, 12:56 PM
Im glad you started this thread, I have a very similar style trunk and though about using a pair of high powered 10s like some DC Level 4LVL in a 4 order but putting the box on the rear shelf, or basicly the gas tank.

Im very interested how this turns out, ill be taking notes :)

GearGuy2001
05-13-2009, 01:32 PM
Your trunk lay out kind of *****. I was wondering how you design these while playing with winisd the other day. Listening to some computer speakers with a 6th order that sounds good.
There any faqs around on designing these?
Yeah I know my trunk ***** haha

http://www.the12volt.com/caraudio/boxes4.asp
and
http://www.the12volt.com/caraudio/boxes6.asp

Those are the only tuts I found, lots of websites just copy that info (sometimes without even rewording it).


Im glad you started this thread, I have a very similar style trunk and though about using a pair of high powered 10s like some DC Level 4LVL in a 4 order but putting the box on the rear shelf, or basicly the gas tank.

Im very interested how this turns out, ill be taking notes :)

Yeah I dont know if you could get enough cubes to fit on the rear shelf with 2 10s. I supposes its possible, I know that rear shelf is huge. My main goal is to get loud in the cabin and without porting everything into the cabin (like a bandpass does) I was worried about "Timing" issues in the sound.

BigJoker
05-14-2009, 06:55 AM
you Marquis will get loud with a ported box :fyi:

if you decided to run DD then i have a box for you already.

mlstrass
05-14-2009, 11:36 AM
Joker's car was quite loud with a single 9515 in a ported box. You might have room for 2 15's ported...