Who knows Close Box for 18w/8531g00e ?

Mingo said:
Here are recommendations from some loudspeaker companies:
Akustyk: 14 litres Qtc 0,71 44 Hz -6dB
Eltek: 18 litres 53 Hz - 3 dB
Strassacker: 16 litres 57 Hz - 3 dB/ 36 Hz - 8 dB

Those figures seem out to me, as far as I know the driver hasn't changed since it was introduced.

For me (using WinISD) 14L gives Qtc of 0.809, 16L 0.772 and 18L 0.742, all have f3 roundabout 58-60Hz.

To get f3 down you will need to use a vented box (which the driver is intended for really), QB3 would be 38L tuning to 30Hz with f3 around 32Hz.