Originally Posted by
davef
Hi Tomker,
What you are experiencing is simply the bass extension limitations of the 170's. You are asking the speaker to reproduce bass notes that it is not designed to accurately reproduce. With a ported speaker, (any ported speaker), if you send the speaker a frequency below the port tune frequency, the woofer will become unloaded from the cabinet (the internal volume of the cabinet no longer acts like a spring to assist in controlling the woofer cone movement). The woofer then moves back and forth creating a lot of air movement but it is not accurately reproducing that frequency. This is precisely what you are hearing...
Keep in mind these are not full range speakers. If you want accurate reproduction of deep bass notes, you will need to add a subwoofer or go with something like our Sierra-1, which has a much lower port tune.
Sealing the ports will make the situation worse, not better.. The woofers in the 170's are not designed for a sealed cabinet. Best option is to do exactly what you did, limit the deep bass going to the speaker by setting a high pass filter.