Building a box for my Audiopulse Axis

[emilimo701 10+ year member]

I'm going for 6 cubes at 20 Hz. 3" x 15.5" slotted port.

I have two main concerns right now. The answer is either yes to both, or yes to one:

1) is 3" x 15.5" big enough to avoid port noise/chuffing?

2) is 3" x 15.5" small enough to mitigate the effects of port resonance? (146 Hz)

Using WinISD pro I have come to these calculations:

Volume: 6 cubic feet

Tuning: 20 hz

Port area: 3" x 15.5"

Port length: 46"

Max port velocity: 28 m/s (19.5hz)

First port resonance: 146 Hz

Subsonic filter: 4th order butterworth @ 17 hz

Excursion peaks (2000w RMS): 15.5 Hz (27mm), 28 Hz (28mm)

Having the subsonic at ~17 Hz evens out the excursion peaks. With flat response down to about 23 Hz, the whole sonic range should be covered, and then some.

Thiele–Small specs for the Axis:

Fs: 22 Hz

Qts: .40

Vas: 126 liters

Xmax: 30mm

Bl (series): 26.2

Re: 4.9Ω

Click to read more...

 

[taylorpro 10+ year member]

please tell me this is for a house.

 

[emilimo701 10+ year member]

please tell me this is for a house.

That was the initial plan. But I decided against it (possibly getting a Dayton reference for my theater) and raised the tuning (yes at first I wanted even lower). Is 20Hz definitely still too low? I want it fairlry flat to (no more than -4db) at 28Hz, and I want at least audible down to 20 (getting some of that 17Hz feeling in some of those super-low bass songs would be a plus). The main application would be tailgating, but I realize even tunes that low 17Hz wouldn't be very "feelable" unless in-car?

Let me know what you guys think

 

[emilimo701 10+ year member]

Bump... want opinions before I start this on Monday