Port firing direction question

[BigBadRod 0]

If I have a traditional trunk (large 300c trunk) and I fire the sub towards the back but fire the port up on the passenger side of the car, does the direction of the port make any difference, up, back side? I assume it would a little if there was resistance from say a seatback or side trim but up into the rear window or towards the empty trunk in the back, will there be much of a difference in the cabin as far as sound etc...

Just got my 15 BL today ($105 extra for DELIVERY WTF?!) and can't wait to get it in... I am going to tune it to 33 or 34 hz

PS: How reliable is the ported box calculator at reaudio?

[bigrank916 72]

You can only get that answer through trial and error. Every car is different so its hard to say what will work, which way.

The re calc will give you a very good approximation but it doesnt account for driver displacement. That, among other things people might say. I used it a couple times and its worked out fine. Just lately I think Im tuned a bit lower than I thought originally because of DD. On the other hand, I really love the sound. Its definately not exact.

[BigBadRod 0]

Thanks bigrank,

I understand the trial and error, its just when you are getting custom built boxes you really only have one kick at the can, so I was hoping maybe someone had some experience with firing the port up into the rear window versus back with the sub.

Question about being tuned lower, does that mean you were aiming for 33 and because of the displacement you went to 31 say?

[bigrank916 72]

Thanks bigrank,

I understand the trial and error, its just when you are getting custom built boxes you really only have one kick at the can, so I was hoping maybe someone had some experience with firing the port up into the rear window versus back with the sub.

Question about being tuned lower, does that mean you were aiming for 33 and because of the displacement you went to 31 say?

What I do know about a trunked vehicle is that you will increase dbs in the cabin by venting the sound though the rear deck. I dont know if youve done that already or if thats even where you were going with it. Other than that, its just check and see. Sucks.

Ya, I think I guestimated too little for the tuning change accounting for the dd. Next time I'll have to break down the actual math and get it just right to make my new enclosure.

[BigBadRod 0]

Thats my plan, build a box with sub on the drivers side facing back and the port on the passenger side going up through the rear deck (should it actually go up through the deck or vent upwards towards the deck?)

I was going to tune it to 35 hz and have the dd take it down to 34, 33, 32 or 31 (I assume the dd can't change it more than that, likely only 1 or 2mhz)

[bigrank916 72]

Thats my plan, build a box with sub on the drivers side facing back and the port on the passenger side going up through the rear deck (should it actually go up through the deck or vent upwards towards the deck?)

I was going to tune it to 35 hz and have the dd take it down to 34, 33, 32 or 31 (I assume the dd can't change it more than that, likely only 1 or 2mhz)

Im not sure if the port should go through the rear deck in your case but Ive seen it done here before. I know guys will take out the speakers and/or cut out extra holes in the deck for more spl in the cabin but Im not sure about venting just the port for increasing spl.

Just not sure how much the tuning lowers when volume is taken away though. Its probably a steeper scale than you think.

[BryanTheCEO 59]

Thats my plan, build a box with sub on the drivers side facing back and the port on the passenger side going up through the rear deck (should it actually go up through the deck or vent upwards towards the deck?)

I was going to tune it to 35 hz and have the dd take it down to 34, 33, 32 or 31 (I assume the dd can't change it more than that, likely only 1 or 2mhz)

Im not sure if the port should go through the rear deck in your case but Ive seen it done here before. I know guys will take out the speakers and/or cut out extra holes in the deck for more spl in the cabin but Im not sure about venting just the port for increasing spl.

Just not sure how much the tuning lowers when volume is taken away though. Its probably a steeper scale than you think.

From my personal experience in a trunk, firing everything back yielded the best results. If possible find a way to open a clear passage for the bass to reflect off the trunk and pass through the rear deck or seat. I my old honda, I made it so the seat could lean forward. You also want 4-5+/- inches from the sub to the back of the trunk, to give room for the sound to come out without cancellation.

I am just drinkin my coffee now, hope that all makes sense, lol..

[BKOLFO4 29]

That RE calculator is BAD. Has a lot of problems if the port requires a 90 degree bend.

Post up the dimensions for the box and someone can check them. . .

[BigBadRod 0]

Just an update:

I LOVE MY BL 15! We did a ported box to 4.96 cubic feet tuned to 34hz. I am way underpowering it right now while I wait for my 1ohm stable comes but it pounds. I have to control the trunk ratlle.

THANKS AGAIN TO THE GROUP AT Fi, I WOULD RECOMMEND THEIR SUBS IN A HEARTBEAT!

[porkchop 304]

i am happy for you, any pics yet?

did you decide to fire it to the rear?

hope so.... it is the better, easier way.

we often loose the rear fill.... allowing this area to help vent the bass into the cabin.

[BigBadRod 0]

Fired the sub and the port towards the trunk. One thing that was strange was that when we measured the terminals, they said 5 ohms...

[BigBadRod 0]

Here are some photos:

Picasa Web Albums - rodfriesen.com - Fi BL 15

The guy built the box to 4.92ft3 and tuned it to 34hz. He also neatly tucked the amps in those two little compartments. I am ordering a new sundown as this amp CANNOT handle it!

[Duran 387]

Very clean!

[jcarter1885 995]

Very nice and stealth .