4th order with JL W6 in car

[russ872]

This if for you gurus out there that have quick and easy access to a 4th order design program. This is for my car, which is a sedan. I already built a sealed box in the trunk for my single 10" JL W6. It sounds good, but is rattleing the crap out of my trunk. My brainy ideal is a 4th order with the port up through the back deck, which means all the sound goes into the cabin. So i have several sections of 11" diameter plastic pipe to use for the two parts of the box. I have a 3-inch port, with flairs at both ends, that is about 14-inchs long, not counting the flairs. The speaker specs:
Qts: 0.497
Fs: 28.5
Vas: 33.4 liters
Xmax: 15.2 mm
Sd: 51.4 sqin
Dia: 25.4 cm
Displacement: 1.9 liters

I need to know the front and rear box volumes and the port length. I can add the required additional volume when taking into account the port area and the driver displacement.

As far as desired parameters, the F3 should be somewhere around, or below 30 hz, with the total box volume as small as possible. Since this is in a car, i think I'm looking for zero Gain from the box design.

I did plug this into a calculator I found. the Vf, Vr and Port length were, 0.51 cf, 0.68 cf and 14.7 in with a F3 of 30 hz and a 1.4 db gain. I'm wondering how close this matches the output of a design program. Thanks!!

Russ

[Volenti]

Bandpass enclosures for cars don't really have an F3 like vented boxes do, at least not one that helps you design one.

Instead you design for a certain "slope", usually one very close what you would get with the driver in sealed.

In your sutiation I came up with a sealed chamber of 0.66cuft, and a vented chamber of 0.8cuft with your flared 3'' vent a mere 2.5'' long (including the flares) I would personally go with a 4'' port (no or mimimal flaring) 4'' long.

This is the raw response (in car response will be different), yellow is sealed in .8cuft, light blue is the bandpass, you can see the bandpass response is similar to the sealed (only louder)

[Volenti]

And for contrast the design from the calculator you found in pink.

[rogermaasen018]

i made this box

[GM]

A couple of things, you say W6, but post specs for the W6v2 except list Qes as Qts, so what do you really have? If v2, then the published Qts = 0.469 and ya'll need to revise your sims.

Also, while some other car audio brands offer 4th order BP alignments on some of their 'subs', JL doesn't for the W6 series, so this gives me pause as to it being a viable option for good performance/long term durability. Only one way to know for sure though.

GM