View Full Version : Box is peaky?

03-28-2010, 06:03 PM
Heres my box design for my single AQ HDC3 15" running 1300w off of a hifonics 2010d.


After displacement I'm tuned to about 38hz with 4.5 cubes. My 45-60hz range is very peaky, anything lower than that rolls of very quickly. Would box rise have something to do with this? I mean when there's a higher note my voltage drops .6v but with a lower note my voltage will drop .2v. LPF is at 30hz. I used to have a 12" hdc3 in a 2 cube box tuned to 37hz and it didn't hit the highs like this box does. Any ideas guys?

03-28-2010, 07:10 PM
Box rise shouldn't be an issue, because as impedance rises as you get closer to tuning, the port helps out and gives you added output to compensate for the power that's being lost due to imp rise. The huge port is possibly the culprit. You have almost 20in^2 per ft^3, which might lead to the peakiness you're describing, as well as the sharp roll-off. With huge ports like that, normally anything below tuning goes to complete **** because the sub just acts like it's in free air...that's the main reason I don't do big ports like that. Smaller ports give you a smoother roll-off and less peakiness in most cases. Personal preference, I guess.

03-28-2010, 07:16 PM
I'd also be nervous not having a 45* piece in the corner of that port, since the design is counting on that port using that corner and turning to make the total port length needed.

03-28-2010, 10:20 PM
Anything I can cut to make the port area smaller?

03-29-2010, 02:10 AM
Add an L to tune to 33 and you will like the result.

03-29-2010, 02:17 AM
Add an L to tune to 33 and you will like the result.

Yes. 33 is absolute *** in my truck. 25-60 is nearly flat, with a little peakiness in the high 30's, low 40's that is sooo nice.

03-29-2010, 02:21 AM
You can slap a 3/4" piece of MDF that's 18.25" long next to the existing port wall to make the port a little narrower and lower tuning a couple cycles. If you're not happy with that, make another one 3/4" longer to drop tuning a couple hz again.

03-29-2010, 03:55 AM
Hmm sounded good tonight for some reason. I'm gonna wait and see how I like it before I do stuff to my box.

Bumpin' Goalie
03-29-2010, 04:02 AM
Is the woofer new? If so, break her in. She'll drop lower with time.

If you do alter the box, I agree with Ryan, add addition pieces of mdf to the internals of the port to reduce size, drop tuning.

Best of luck.

03-29-2010, 04:03 AM
try lowering the SSF first, just to be sure it's not cutting out the lows. Many of them are way off what the dial on the amp might read.

You could also make a port reducer to drop down to around 16^2 of port area per cube.

03-29-2010, 04:06 AM
Woofer is little over a month old, still kinda stiff. I'd say its about 60-70% broken in. What would a port reducer look like?

03-29-2010, 04:15 AM
basically a "box" that fits inside the port and reduces the height to get you down to 16^2 or port area per cube. So it would be as wide as the port and as deep, but you'd need to calculate the height going off your width and net cubes.

You going to the comp in Madison on the 11th?

03-29-2010, 04:33 AM
Run sealed

03-29-2010, 04:41 AM
run sealed


03-29-2010, 05:33 AM

x2....Who the hell runs a HDC3 sealed....

03-29-2010, 09:58 AM
Add an L to tune to 33 and you will like the result.
33 is pretty low for an hdc3. He might not like it. I don't have the hdc, but for my 12s I tune about 5hz higher than normal and still get the sound I like.

03-29-2010, 10:16 AM
Tune it lower, and maybe take away some of the in^2 of port.

03-30-2010, 01:50 AM
Or tune to 27 :) That is working well in my setup!