2 15" Fi BL

[seanbw 1]

"The tuned port in these systems increases efficiency by nearly 3 dB in an optimum enclosure, and the roll-off frequency can be much lower, often by as much as 1/3 - 1 octave below a sealed enclosure. Think of the extra 3 dB as equal to the output you would get using twice the amplifier power on the driver. Add several ported drivers together and you can achieve impressive SPL's indeed! Because of the ports damping characteristics on the driver above Fb, distortion levels are also lowered because driver excursion is less. So, with nothing more than a properly designed optimum vented enclosure, you have very efficient bass reproduction with several advantages over an optimum sealed enclosure."

from http://diyaudiocorner.tripod.com/dilemma.htm

15" ported in optimal = (approximately) same output as two 15" sealed in optimal enclosure. you do not have the space for two 15" q's. you will be under 4cu net after driver displacement and bracing which you will need with that much woofer on such a small baffle. this is why we are recommending one 15" btl, it is substantially more efficient so watt per watt it will get louder than the Q's, and with the ~3db gain from an optimal ported enclosure you will be louder than than the two Q setup. this has been said in so many ways 4 or 5 times in this thread, hence the dead horse comment.

Edited December 15, 2008 by caligreen

[sandsnip3r 0]

ok, well thanks a lot man!

but just as other people may have said it... they were saying maybe, like they dont know, but i see that you know whats up... so

so Caligreen, do you think that i sould built my enclosure to the exact same specs as what you have?\

cause thats like perfect size...

Hey, when i add it up, 34x18x16.5 inch box comes to like 5.5 cubes... the sub displacement is like .2cubes each.... and even if i get 1 cube of bracing. ill still be over 4 cubes...

Edited December 15, 2008 by sandsnip3r

[seanbw 1]

ok, well thanks a lot man!

but just as other people may have said it... they were saying maybe, like they dont know, but i see that you know whats up... so

so Caligreen, do you think that i sould built my enclosure to the exact same specs as what you have?\

cause thats like perfect size...

Hey, when i add it up, 34x18x16.5 inch box comes to like 5.5 cubes... the sub displacement is like .2cubes each.... and even if i get 1 cube of bracing. ill still be over 4 cubes...

your welcome, i'm glad im starting to make some sense here. you also have to factor in the volume the port itself removes from the net volume. i was in the same position you are a few months ago, my old amp blew and i was tired of my jl twelves. i really did my research and i think i made the right decision with my setup after a few mishaps and wrong turns (as of now it gets louder than i can listen to). i don't really know that much as the setup i have was my first custom design and install but i have researched the theory of spl design a lot on this forum and other places since my build though. when it comes to designing your box you can ask in the design forums here for help or you can pay like ten bucks and have professionals like thumper and bj fish design your box for you. i recommend the btl because it is the most efficient sub fi makes, so for every watt you put on it, it will be louder than the q, bl or ssd. you don't need the full 2k wrms or whatever they can handle. if you provide what woofer and those dimensions for your enclosure to bj or thumper they will draw you up a perfect enclosure to match your space and the woofer.

[sandsnip3r 0]

ok, but did you get what i said about the sealed? id have the perfect size sealed enclosure if i used about .8-1 cube of bracing...

[seanbw 1]

ok, but did you get what i said about the sealed? id have the perfect size sealed enclosure if i used about .8-1 cube of bracing...

i know what your saying, i just don't think the output of the Q's will match the btl. i also don't think your car can adequately power two 15" q's the way you expect it to, they are substantially less efficient than btl's and jap cars rarely come with more than an 80-110 amp alternator. without adding extra batteries and upgrading your alternator i do not think you can provide enough power for two 15" Q's to attain the output you are looking for. i know that the amperage draw from my sundown 1500 watt amp is enough to damage my 80amp alternator and turn the vehicle off. again i'm no expert, but the situation that you are in specifically is very similar to the one i was in. and i believe i came out on top while spending under $1000 in total on my setup.

[sandsnip3r 0]

man, i dont know what to get...... im leaning more toward the 1 btl.... but idk....

it just seems that the 2 Qs will be fine...

[ShaneSauce 2]

man, i dont know what to get...... im leaning more toward the 1 btl.... but idk....

it just seems that the 2 Qs will be fine...

Well we could answer that.

Do you want sound quality or stupid loud?

[sandsnip3r 0]

SQ is Qs

Stupid Loud is BTL

im gonna go for the BTL i think.....

[sandsnip3r 0]

and for the box... what if i use http://www.reaudio.com/speaker_box/LPort_Box_Calc.html

and what freq do i want?

i listen to like ALL rap....

[ShaneSauce 2]

I would go with 4-4.5ftcuft after all displacements.

All rap I would say 30-32hz.

And BTL's like allot of port so I would go for about 60-70 square inches of port.

[sandsnip3r 0]

i cant get that big for the box.....

go to

http://www.reaudio.com/speaker_box/LPort_Box_Calc.html

and put in

width 34"

height 16"

depth 18"

depth 18"

wood thickness 1"

port width 4"

port length2 22"

for all the blanks in order

and tell me what you think.. cause thats about as big as i can get and the freq i can get

will that work with that port shaped like that and all?

[sandsnip3r 0]

well, everything looks good, gonna order it soon,

do they allow in-store pickup?