http://audioroundtable.com/ArraySpeakers/messages/529.html

Jim Griffin suggested ports to the back but how do I calculate port lengths.

I’ve tried WINISD which for 17 NBS drivers gives me a port length of 125 cm for a 50 mm dia pipe. But is the initial volume the software calculates for one or all 17 drivers if so it’s returning a ridiculously small volume of less than 4 litres for 17 units.

Assuming it’s the volume for one speaker I’d guess that’d be about 3.25 litres so adjusting to this I get the 125 cm length which is not practical/possible in the 300 mm depth, see

http://www.greenie512.net/greenie512/html/future_project.html and
http://www.greenie512.net/greenie512/html/porting.html

Most ports in array designs I’ve see are quite short …. where am I going wrong.

Cheers - Phil