Mojo Bandpass

[trini-mix]

So I've spent alot of time reading up on bandpass enclosures and was wondering if its possible to do a bandpass box with dimensions of 36L x 23D x 16.75H with 2 12" Memphis M3 Mojos. I currently have them in a slot ported box and was wondering the bandpass would make them sound louder. Im still a noob on this so give me a break. Thanks

[KingPen]

bandpass box is as the name implies, it limits the frequency band, much like a subsonic and LPF.

There are many kinds of bandpass enclosures. What kind are you referring to and what is your goal?

[trini-mix]

Im not sure what type is best for mojos but I know that I want a port through my armrest and tuned to about 34 hz..I want it low n loud. Im just not sure if a bandpass is practical within those dimensions.
Memphis recommends ported but I've heard that bandpass boxes are capable of sounding twice as loud with the same amount of power.

[KingPen]

Originally Posted by trini-mix

Im not sure what type is best for mojos but I know that I want a port through my armrest and tuned to about 34 hz..I want it low n loud. Im just not sure if a bandpass is practical within those dimensions.
Memphis recommends ported but I've heard that bandpass boxes are capable of sounding twice as loud with the same amount of power.

I can't speak for the mojo's directly but I could probably give some helpful general advice. There are really two common types of bandpass boxes used. 4th and 6th order. A 4th works well for subs that are designed for sealed enclosures and a 6th favors subs designed for ported enclosures. There can be a little cross between the two but that's just kind of a general rule to follow.

Both can play low but getting a 6th to do it is a pretty daunting task and requires a lot of trial and error in many cases.

In the space you gave that would be a pretty tight fit for two 12's in a 6th or 4th. Your gross internal space is 6.5 cu ft. The below picture is one of my 6th in my scion for a single 12. Its 5.9 cu ft gross

[98Civic]

I think that your space is probably too small, but I have never designed a 4th order, or a sixth order. However I have read up on some great threads that explain the process and what you should do to achieve your goals.

It sounds to me that you are trying to get as loud as you possibly can. To get a 4th order to be very loud you usually want to go for a 3:1 ratio or larger. That means you want the ported chamber to be 3 times the size of the sealed chamber (or larger). The larger the ratio, the louder it will be (generally). If you do not have the space available for such a large ratio box, you are actually better off sticking with your ported box for loudness. Obviously there is much more too it than that, but it is beyond my knowledge.

[KingPen]

well on the contrary he said he wanted it to play low as well. When you go oversized on a 4th like you mentioned it peaks hard in the upper frequencies and less in the lower. Gett it to peak in the lower would mean a larger sealed portion but your killing output either way.

Ported is honestly your best option.

[98Civic]

Maybe you should tell us the specs on your current enclosure. It is possible that it isn't optimal and you could gain from a new design.

[Squeezumz]

Originally Posted by 98Civic

Maybe you should tell us the specs on your current enclosure. It is possible that it isn't optimal and you could gain from a new design.

This. If you want low tune low. A 4th that plays low wont be any louder than a ported except in the upper end.

[KingPen]

Originally Posted by Squeezumz

This. If you want low tune low. A 4th that plays low wont be any louder than a ported except in the upper end.

To be honest a properly Build ported would end up being louder then a 4th on the low end and like you said the 4th would be louder in the upper end.

[trini-mix]

Originally Posted by 98Civic

Maybe you should tell us the specs on your current enclosure. It is possible that it isn't optimal and you could gain from a new design.

I have a slot ported box tuned approximately to 30hz with the dimensions of 36L x 23D x 17H made of 3/4 mdf. This is the absolute biggest box I can fit and be able to remove when needed. Any recommendations?

This is all I got from Memphis

and this :
2008 Enclosure Recommendations.pdf

[98Civic]

How much port area?

[southerntrendkill]

Originally Posted by trini-mix

I have a slot ported box tuned approximately to 30hz with the dimensions of 36L x 23D x 17H made of 3/4 mdf. This is the absolute biggest box I can fit and be able to remove when needed. Any recommendations?

This is all I got from Memphis

and this :
2008 Enclosure Recommendations.pdf

anyone think a lil big for 2 12s or only depende on subs and Power to them?

[KingPen]

whats does your port opening measure?

[trini-mix]

Originally Posted by KingPen

whats does your port opening measure?

I cant remember off my head but I believe its 21.5" x 4.25" so 91.375

This is a picture if you were wondering what it looks like:

[cxa0897]

I don't think you are getting louder than that box without more space or more power

[97_eldo]

looks like around 15.5 x 4.25 = 65.875 sq in port
based on the stated height of 17"

[profundus-sanus]

how long is your port? it would have to be around 30 inches to get a 30hz tune.

[98Civic]

Yeah the box seems fine to me too. What amp do you have running them?

[KingPen]

Yea your box looks all good.

Things you could do....

Raise the tuning a bit, you lose the lows but will peak louder.
Add more power
Get better subs and more power
consider the Car as a factor - Placement of the box and cancellation inside the car could be causing your problems.

[trini-mix]

Originally Posted by 97_eldo

looks like around 15.5 x 4.25 = 65.875 sq in port
based on the stated height of 17"

oh yeah your right my bad

[trini-mix]

Originally Posted by profundus-sanus

how long is your port? it would have to be around 30 inches to get a 30hz tune.

its about 24 inches..what would that make my tuning frequency? I used the Torres box calculator and that sounds incorrect based on that program.

I use a earthquake ph5000d.. it puts out 3000w @2 ohms according to their specs. I have the box facing toward the trunk because I've heard when facing inside you need to seal off around the box.

[profundus-sanus]

Originally Posted by trini-mix

its about 24 inches..what would that make my tuning frequency? I used the Torres box calculator and that sounds incorrect based on that program.

I use a earthquake ph5000d.. it puts out 3000w @2 ohms according to their specs. I have the box facing toward the trunk because I've heard when facing inside you need to seal off around the box.

i can assure you my calculations are not incorrect. at 24 inches you have 5.24 cubic feet tuned to 32.5hz w/ subs displacing .4 cubes total.

is it 24'' long would mean the port board from the front goes to 4.25 from the back of the box then goes 1'' towards the right of the box. is that correct?

[trini-mix]

Originally Posted by profundus-sanus

i can assure you my calculations are not incorrect. at 24 inches you have 5.24 cubic feet tuned to 32.5hz w/ subs displacing .4 cubes total.

is it 24'' long would mean the port board from the front goes to 4.25 from the back of the box then goes 1'' towards the right of the box. is that correct?

Thats correct. I guessing my calculations were wrong then. Thanks for letting me know.