New subwoofer project "SuperNova"

[orangeman]

I am using this driver...

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to build my next subwoofer. Basically, It is a dual voice-coil driver that has a whopping 2" peak-to-peak excursion and a magnet that weighs an impressive 150oz. The 5 magnet vent design allows the subwoofer to efficiently cool itself, even at high levels. It also lowers the pressure inside the magnet structure which virtually eliminates air pressure noises that are problematic in many other high powered speakers. The cone is crome-ion deposited with a large rubber surround. Other features include silver flexlead wiring and gold plated binding posts.

I used a couple of programs so I could obtain the desired results and have tuned it down to 24Hz. The net internal volume of this unit is 4 cubic feet and the -3dB point occurs at 21Hz.

 

[454Casull]

What is the driver's model?

 

[ThomasW]

Why would you use such a high tuning point?

 

[sobazz]

I don't quite understand why you would want to go for this alignment (picked from your website):

An externally hosted image should be here but it was not working when we last tested it.

 

[officeboy]

Yeah, after room gain is added in that mid 20's peak could get ugly…
Be interesting to see the in room response.

 

[orangeman]

The driver is a Maxcaliber CA12150. I was not totally satisfied when I tuned lower (spec-wise) however, since I have not yet designed the enclosure, I will attempt to see just how I can accomodate the extra-long port, while keeping the vent mach down to acceptable limits.

Here are the specs...

qts=0.36
vas=56L
fs=26Hz
Re=4ohms
xmax=0.028m
z=8ohms
qms=8.77
qes=0.37
spl=93.9dB
pe=900w
bl=18.00
dia=0.305m
sd=0.048sqm

I was using a 6" port and if I tune it down to 18Hz then I will need a 48" port and I am a little concerned with the 8x ratio of diameter to length of port.

I tell you what, I am open to advice regarding the tuning. If I do tune lower then I may also have to rethink a 6" port and go with multiple (2 or even 3) smaller ports (got to keep the length down to reasonable levels so I can design the enclosure.

I forgot to add that I have 18" sonotube currently. I could port from the top and have the driver mounted at the bottom.

 

[mikee12345]

High power + small box volume + low tune = impossibly long port

use a good woofer on a box its optimal on. If a decent port wont fit,compromises must be made.

Oftentimes carwoofers with tiny box requirements have impossible ports.

My 175L jbl 15" doesnt have this problem

 

[sreten]

Hmm...............

A 2 cuft Vas driver in a 4 cuft box is nothing like optimum design.

My estimations show 60L (~ 2cuft) box tuned to 20Hz is a
big as you should go, which will give -6dB at 20Hz and a far
more room friendly response.

sreten.

 

[orangeman]

I could of course place it in a ~56L box (the designed vas) and tune to 20Hz. Can you guys run the new numbers and see what you come up with. I will do the same as well.

Thanks,

 

[orangeman]

I have decided to go with a smaller 2 cubic ft box for this driver. I will drive it with a nice 350 watt amp I saw that would be nice for this driver/box.

Here

 

[454Casull]

There's always the option of using 2 passive radiators...

 

[orangeman]

Don't have the amp yet. My question. Are there 3" port flares available that don't flare out too much? You see, my two 3" ports are about 1.5" from the edge of the cabinet...

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so anything larger will not work.

 

[johninCR]

From the pic, it doesn't look like there's any bracing in that cab. The baffle could use some reinforcement too. You need both, especially with a driver that has a 2" stroke.