designing a sub enclosure (1 Viewer)

[Matt McD]

Hi my name is Matt, I have been looking over these forums for a while now and have decided to build my own subwooferbut I have a few questions.
1. If using port flares does this effect the port lenth oposed to square ends?

2.Im going to use an Aura force12 woofer for my project as I already have it from my car stereo days. Specs as follows
Qts 0.49 Qms 8.20 Qes 0.52 Vas 139.9 Liters Fs 24
Spl 90db Re 4 Pe 250wrms Z 4 dia 0.305m Xmax 9mm
Is this a good driver to use? I used WinISD to plot it but I really dont know what to look for. I used a box of 200 l tuned to around 19Hz. This is smaller than what the program sugested but is still a big box. If someone can sugest a diffrent/better box size or tuning it would be apreciated.
Im going to power it with a 250w plate amp.

3. Is this a good woofer to use? I know there are better woofers out there but I already have this. Or am I wasting my time with it?

Thanks Matt

 

[Matt McD]

bump Can anyone help?

 

[Ryan Schnacke]

Seems like it should be an okay driver for HT use, especially since its already paid for. But you're right, 200L is a really big sub. It looked okay to me in 140L tuned to 20-21Hz. You lose a little on the low end, but its probably in the tactile-only region. But room gain will help and besides, the slightly higher tuning you can push just a little more power before hitting excursion limits.

Speaking of excursion limits, I found that it reaches them pretty fast - like around 60 - 75 watts with the tunings we're discussing. That's seems a bit early to me. Maybe in my haste to enter the params I messed something up ... but I do get 90.76dB USPL in WinISD pro which is pretty close to the 90dB specified sensitivity.

If you can scrounge up some amplifier to use, at least temporarily, then you could try the sub out for only the cost of the enclosure materials and a bit of your time.

 

[Matt McD]

Thanks for the answer
Where abouts in winisd can you check for excusion limits?
and what about the port lenth with flared ends will it change longer/shorter as oposed to just square ends?

 

[Ryan Schnacke]

The standard WinISD doesn't give excursion graphs. But WinISD pro does.

The rule of thumb for flares is to make the port 1 inch longer than you would when using a straight port. Of course this will vary somewhat depending on how big the flare is, but that's what's recommended for the aeroport sold by PE.