Port tuning on my subwoofer box

[Nikitaaa]

Hey guys, I got measured on a termlab and was upset with my results. I hit a 139.5 with my single hdc3 15 on 1700 watts.

I thought about how I could make my setup louder and my mind crossed my subwoofer box. I thought it was tuned to 35hz when I built it but it turns out it peaks at 42hz. When I was building the slot port, I didn't make sure the ports were 90 degrees.

Basically, I think it's tuned into the 40s now because the port gets more and more narrow into the box. Is this harming my spl?

[Nikitaaa]

Also, the box is about 3.75 cubic ft.

[Dax]

I would think it would mess with the sound, but i don't know about the spl, maybe you could build another box to the same specs as you thought this one was and make sure the port is right this time. See which gets lounder

[Nikitaaa]

I really would like to do this, only problem is money is tight..

I will do it if I'm absolutely sure it's harming me :/

[412 CVX]

well not keeping the port the same width all the way through is a bad thing, but i think it's tuned right. cars usually peak slightly above the box's tuning frequency.

build a new box if you want. maybe a little more port area. i'd think that would help you slightly.

[Nikitaaa]

Okay, so more port and maybe make the box around 4.5 cubic ft instead of 3.75?

[streetfighter]

Are you looking for max SPL, or to have the box tuned to 35 hz? Tuning to 35, may be worse SPL# wise than the 40's you think it is.

Port measurements as far as width, height, and length (centerline of port) are required to verify your tuning question.

Also how much it tapers, 1/8" or 1" and where the taper is. It will change it some but depends on variation of the port size.

[Nikitaaa]

Well the taper is no more than .5 inches. Starting smaller and getting larger and larger as the port extends.

I'm thinking that I make the box larger, and change my port to fire backwards, sub up. And hopefully get a nice increase. I have a Subaru Outback.

[rogue]

Okay, so more port and maybe make the box around 4.5 cubic ft instead of 3.75?

Yeah Id go least 4.5 (and make sure thats what you have after displacement) and do around 75-90 square inch of port. I would keep tuning around 35-40 tho.

[412 CVX]

i can't tell you for sure... it's more of a guess and check thing, but more port area should definitely bring you better scores. i hear AQ subs like big boxes, so possibly somewhere in that volume range. i'd probably do about 4-4.25 cubes if you have the room to spare.

gotta be careful though, you're overpowering the subs some