atlas 15" port length?

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