atlas 15" port length?

[djblock]

atlas 15" port length?

Having trouble calculating port length (such a newbie). I built an
11 cubic ft box for tuning at around 16hz. Using two 4" ports can
someone give me the lengths of each. Thanks

 

[richie00boy]

For multiple vents, the equivalent diameter is:

square root of ( (d1 * d1) * (d2 * d2) )

I have a vent calculator on my website, but it uses metric units. 1 cu ft is 28.3168 litres. 1 inch is 25.4 mm. www.readresearch.co.uk check the 'utilities' section.

 

[Tweeker]

2 20" long 4" diameter ports would do it. Used this site to calculate. Effective port diameter is 5.66 inches. Would recommend using flared ports.

 

[Collo]

Hi dj,

thats about right. WinISD gives the following specs for the driver in low QTS config with 11 cu ft box, 16 hz tune:

Two 4inch ports @ 20.5 inches long - Port air velocity is 15 metres / sec @ 20hz and 23.5 m/sec @ 16hz. - port resonance 329hz

If you go to Three 4inch ports @ 32.5 inches long , velocity drops to 10 m/s @ 20hz and 15.7 m/s @ 16hz - port resonance 208hz

Collo