[Sonnie]

You can post a graph down to 2Hz, 5Hz, 10Hz, if you want... several people do... especially in other areas besides the BFD | REW Forum. 15Hz is not mandatory by any means, merely a request for this forum area, as well as the "request" for the stated axis parameters is only posted in the BFD | REW Forum.

In general, our "request" for the stated axis parameters are for those who are using the BFD and asking for help smoothing/taming their response. We are not necessarily comparing graphs in the BFD | REW Forum to see whose sub has the best extension. And as previously stated, most of us can't do anything with the response below 20Hz anyway.

I actually encourage others to post lower graphed responses myself, in the other forums such as the DIY Subwoofers and Home Audio Subwoofers forums. I like seeing extension response graphs.