Rate this sealed Kappa Perfect design

[gus6464]

I messed around last night with Box Pro putting a design together for a sealed Kappa Perfect 12 VQ according to TLS' input on another thread and this is what I came up with.

Box is 15x15x13.5in with internal volume of 1.23 cu ft. This is a simulated graph with no internal bracing and heavy fill.

Wanting a pair of stereo subs that will only be used for music and no HT whatsoever.

Box Parts (Square Prism)
1 Top, 1 Bottom: 13.5 (c) x 15 (b) in
0.75 (thick) in
1 Front, 1 Back: 13.5 (a) x 13.5 (d) in
0.75 (thick) in
2 Sides: 13.5 (a) x 13.5 (c) x 0.75 (thick) in

 

[WmAx]

I messed around last night with Box Pro putting a design together for a sealed Kappa Perfect 12 VQ according to TLS' input on another thread and this is what I came up with.

Box is 15x15x13.5in with internal volume of 1.23 cu ft. This is a simulated graph with no internal bracing and heavy fill.

Wanting a pair of stereo subs that will only be used for music and no HT whatsoever.

Box Parts (Square Prism)
1 Top, 1 Bottom: 13.5 (c) x 15 (b) in
0.75 (thick) in
1 Front, 1 Back: 13.5 (a) x 13.5 (d) in
0.75 (thick) in
2 Sides: 13.5 (a) x 13.5 (c) x 0.75 (thick) in

If you are using high power amplifiers, I would recommend 3 or 4dB boost in the low end using a parametric band. If you use a DCX2496, you can use two bands to achieve the perfect flat response, to 28Hz or so, and keep a very good dynamic range available. You may, depending on the excursion models, apply a high pass filter around 22-25Hz, 4th order, Butterworth, to limit excursion. It depends on the specific model though, and I have not modeled your configuration yet. I'll get back to you.

-Chris

 

[WmAx]

Okay, here is my recommendation(assuming you are using minimum 1000 watts per driver) for the 1.3 gross volume sealed system with the 12Vq in mid-Q insert mode:

Parametric Band No. 1: fc=29Hz, Q=2.0, Gain= +4.0 dB
Parametric Band No. 2: fc=70Hz, Q=0.8, Gain= -1.4 dB
Highpass Function: Butterworth, order: 2nd, fc=25Hz

The above filters allow maximum extension and flatness with highly controlled excursion. These settings are easily utilized if you are using a Behringer DCX2496 device.The high power amplifier is needed to insure no clipping occurs in conjunction with the E.Q. boost, in cases you are driving high levels. F3 of above is 32Hz, F6 is 27Hz, F10 is 24Hz.

-Chris

 

[gus6464]

So even without heavy bracing internally it should be ok? I was thinking of adding some bracing internally but I assumed that would decrease the internal volume of the box causing the modeled specs to be inaccurate. Or would lining the interior of the box with dampening material and fill be sufficient?

I was thinking of bracing the box by cutting some small diagonal sections and putting it in all corners since I don't have much room to work with.

 

[WmAx]

So even without heavy bracing internally it should be ok? I was thinking of adding some bracing internally but I assumed that would decrease the internal volume of the box causing the modeled specs to be inaccurate. Or would lining the interior of the box with dampening material and fill be sufficient?

I was thinking of bracing the box by cutting some small diagonal sections and putting it in all corners since I don't have much room to work with.

A 1" x 3" oak cross braces in all axis will be fine. That is, run them from side to side, top to bottom and then run brace from center of back panel to connect to the middle of the other braces. Be sure the braces leave about 1.5" clearance behind the Kappa motor for the motor to vent properly. The braces will be just a little off center, being more towards the back, to account for the motor depth of the Kappa Perfect driver. Use a double thick front baffle; and besides - you can only flush mount a driver of this size if you have a double thick front baffle. Cover the fiber based insulation board with cloth or another filter material to prevent fibers from entering the Kappa Perfect's motor system, which could potentially cause damage to the motor.

You still need to use appropriate dampening materials internally. For an enclosure of these dimensions, cover the interior walls with 2" of high density fiberglass or rockwool board, in the density range of 4-8 lbs./ft^3 will be appropriate. If you are in the United States, and you can't find a local supplier, I can sell you enough to do the cabinets for very low cost. PM me if you need me to supply some.

-Chris