60litre box tuned to 20Hz without PR?

[SkinnyBoy]

basically as the title says.. just seeking sugestions on how to go about it.. in this box the sub gives a -3dB point at 30Hz... and I intend on using it in the car, and house.... problem is ofcourse, the 90cm long port.. lol THANX!!

[kelticwizard]

A 3" diameter port, flared at both ends, is said to give equivalent noise to a 4" diameter port non-flared. And a 3" port will only be 19", (50 cm), as opposed to 36", (92 cm).

[SkinnyBoy]

Originally posted by kelticwizard
A 3" diameter port, flared at both ends, is said to give equivalent noise to a 4" diameter port non-flared. And a 3" port will only be 19", (50 cm), as opposed to 36", (92 cm).

thanks for that... looks like its 3inches then... excpet... thats 75mm... my friend used an 85mm for a 10inch woofer with smaller X-max to the one I am using, and his port chuffs... (no, its not flared) If I do use a 75mm port and flared it, it would really suck if it chuffed

[SkinnyBoy]

for those interested.. this is the woofer...

http://www.advanceae.com.au/car/prod477.htm

check out the recommended enclosures... lol

25litres tuned to 25hz with a 50mm diameter port... 63m/s port air velocity at 20Hz.. :P nearly 70m/s at the fastest point

40litres tuned to 27.67Hz(?) 50mm port AGAIN!!! NEARLY 90m/s AT 22HZ!!! lol

[kelticwizard]

Well, flares on both ends are supposed to give noise performance similar to a non flared port of twice the cross section area, (not twice the diameter-big difference.

So a 3' flared port should give performace to a port of 106 mm diameter. Compared to that, the difference between 75 mm and 85 mm is not much.

I can't guarantee it won't chuff. I can only go by what is generally accepted on this matter.

[kelticwizard]

By the way, when I say flared ports, I am referring to the gradual flared ports by Precision and perhaps other companies. Like the port on the right.

The port on the left has a flare of sorts, but it is short and does not carry the benefits of the flared port.

By flared ports I mean the gradual flare, like on the right.

[mikee12345]

Port compression. Loss of SPL over what is modeled due to tiny port...

dont try the impossible and have a half assed port skinnyboy-

get small box sealed woofers
get large box ported woofers
that way u avoid the problem of 1cubic ft boxes tuned to 20hz while having ports high enough area for low compression while still not being 99metres long

Cheers!

[SkinnyBoy]

but which one would you prefer? (max spl btw)
60litre tuned to 20Hz vs 60litres sealed.... the woofer really suits either... but only if you can tune it low enough.. its actually very similar to the 10inch Sony Xplod... except the woofer has twice the X-max

[rabbitz]

From a B&W sub and only 65mm dia. Got it working with a 10" Peerless XLS and no chuffing here. I reckon the 65mm x 250mm long (including the flare) is probably equivalent to a 102mm x 668mm long port.

[SkinnyBoy]

Originally posted by rabbitz
From a B&W sub and only 65mm dia. Got it working with a 10" Peerless XLS and no chuffing here. I reckon the 65mm x 250mm long (including the flare) is probably equivalent to a 102mm x 668mm long port.

umm... ok... lol thanx.. I think...