port noise issue and lack of output - HELP!

[valin 10+ year member]

Specs:

Memphis 4KW - currently wired to 1.8 ohms for sub break in

Two DD9515's - dual 1.8's - fresh recones

Two Kinetik HC2400's

I built an enclosure that measures 58" wide, 17.5" tall, and 23" deep with a double baffle, and 132 sq. inches of port. The box is just over 8.5 cubes after displacement. The port measures 16" tall x 8.25" wide, and 16.5" long. All corners are 45'd.

I am having issues with port noise and output. Since the port is in the middle of the enclosure, and is 16.5" long, there is 4.25" of depth at the end of the port on each side to the rear of the enclosure. I am getting a severe vibrating noise which I am assuming is port noise. It seems to be at higher frequencies, and dissipate at lower frequencies. You guys have any ideas? Also, the output seems to be extremely low.

Here's the pics of the enclosure:

Bracing:

Finished:

Click to read more...

 

[kyleorsini 10+ year member]

Nice box

 

[DNick454 10+ year member]

Looks like it has plenty of port area for its size and volume. What's it tuned to?

 

[skmfkr 5,000+ posts]

15.5sq inches of port area per cube u should be fine.

 

[Rock krusher 10+ year member]

I think the problem is that your port is only 4.25" away from the back wall. I don't think thats good when your port is 8.25" wide. You're choking the port off.

 

[valin 10+ year member]

I must have a wiring issue inside the box. If I run one sub at a time at 0.9 ohms, it sounds great. I am going to pull the subs and check out wtf is going on.

 

[skmfkr 5,000+ posts]

I think the problem is that your port is only 4.25" away from the back wall. I don't think thats good when your port is 8.25" wide. You're choking the port off.

oh yeh i didnt pay attention do that. if u can cut those port walls down like 4" and have them turn i guess about 4" or so on each side that might help. if it was me i would have just done the port and subs up and the port on the driver side. and kept the net volume under 8cubes

 

[valin 10+ year member]

Bingo. It was human error. I wired each sub in the enclosure to 0.9 ohms, and each sub has it's own input on the outside of the enclosure. When I ran that in series, I ran amp positive to positive on one driver, and then amp negative to the positive on the other driver. Then neg to neg on the enclosure outputs. I didn't mark the bolts clearly enought, and thought I read positive when it was a neg. becaues of a shadow. It's all good now.

I'm only giving the subs roughly 2000 watts ATM, and it moves some decent air. The subs are fresh recones, so I'm going to take some time and break them in and not push the system for now. In a month or so i'll bump to 4KW //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif