Hi -- I'm going to build the AR.com DIY speakers that Ed designed. I am buying some pre-made cabinets for them and need to know how the port tube affects the sound. At PartsExpress, there are a couple different types -- straight and flared. Here's the flared one that I'm thinking about:


The question is, since this one is almost 4x the cost of their straight 2" ID tubes, is it worth the extra expense?

Secondly, how do you "tune" a port tube? It appears that Ed tuned his design to 55Hz, but I have no clue how/if/why to change that with a different tube. Would this flared tube change the tuning, and if so, how do I measure and adjust that?