Subsonic filter: need one

[stcurell]

Where can I get one, how much $, recommendations?

I was thinking around 10 hz would be appropriate if it were a fixed freq.

I am planning to build one of these which is an A2-300 with slightly more output

Does anyone use the eD EQ.2 and how do they like it? Is two frequencies really enough? It has an adjustable subsonic filter. ($100 or $85 if I can get the package price)

I may go the way of the Behringer Feedback Destroyer with REW, but it doesn't have subsonic filter, may be expensive with $150+microhpone+subsonic.

What is a good microphone to use with the Behringer? (at a reasonable price)