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Discussion Starter #1
Hello - I am brand new to this forum but have tinkering with Home and Car Audio for the last 15 years.

I decided to take the plunge and build my own Home Theater subwoofer cabinet because the subs in my price range were pretty poor quality. The models I really liked were far too expensive.

I found a great deal on a pair of Cerwin Vega VMAX15.2 subwoofers.

The specs are as follows:

No. of Coils: 2
Sensitivity ([email protected]): 87.36dB
Power Handling RMS: 600 Watts
Nominal impedance: 2 ohms
Voice Coil Dia.: 2 1/2" /65mm
Mounting Dia.: 14 3/32" /358mm
Mounting Depth: 7 1/8 /181mm
Spkr. Displacement: .22cu ft /6.2 liters

Fs: 22.6Hz
Qts: .47
Qms: 4
Qes: .53
Vas: 2.9cu ft / 82.32 liters
Xmax: +/-0.8" /17mm
Revc: 1.32 ohms /coil

WINISD shows an EBP of 42.6 so I initially modeled a sealed enclosure but I wasn't really happy with the Transfer Function Magnitude curve below 40Hz. After some tweaking I modeled the following ported enclosure:

QTY 2 Cerwin Vega VMAX 15.2
Internal Volume: 10 cu ft (shared airspace)
Port QTY: 3
Port Diameter: 6"
Port Length: 54.64"
Tuning Frequency: 19.52Hz

I am little leary of porting these subs because of the low EBP but the transfer function magnitude curve looks amazing and with the 3 large long ports (though they would need to be elbowed to fit inside the box) would really cut down on port velocity and noise.

Coupled with the Behringer EP4000 running at 8ohms bridged both woofers should get plenty of power. For the life of me I can't figure out how to get WinISD to model SPL or cone excursion. Could someone with a little more experience building diy subs take a look at this setup for me and let me know if it looks good or if I should go back to the drawing board.

Thanks!!

Brad
 

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For the life of me I can't figure out how to get WinISD to model SPL or cone excursion.
You need the Sd for that, it's not listed so use 800 cm2 which is about right for a 15 inch sub. Modeling shows 2 subs in 12 cu.ft. tuned to 18 hz looks good. Input power is 1200 watts with a high pass filter at 15 hz to prevent over excursion. Porting would be a 8 inch diameter tube 29 inches long to keep the port air speed at 27 m/s.

CV VMAX15.JPG
 

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Discussion Starter #3
Wow thanks for the quick response. I am much more reassurred now that I can see when excursion will attempt go beyond rated xmax. As well the SPL curves look really nice and flat, matching the transfer function magnitude curves. This should be a nice box.

Now how do I go about setting up the 15Hz hpf?

Thanks

Brad
 

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Discussion Starter #5
I just mapped this enclosure out and see that cone excursion goes slightly beyond rated XMAX at 25Hz with 1600 watt rms power. Is this OK?

Generally what is a good port velocity cap. What should I avoid going beyond (When does it become audible noise)?

Thank You

Brad
 
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