Of course, one good measure is to put you hand on the sub and see if things are moving. :)
Homemade sub used with Sonus Faber Olympica III
I have Sonus Faber Olympica IIIs as my main speakers being run from Classe’ CT-M300 monoblocks. I want to add more low end to this system and I have some JBL-L150As sitting around that have the lowest bass I have ever heard that I would like to transform into the subwoofers for this system. I disconnected all of the internal crossovers in the JBLsand added heavy duty gold binding posts as well as good quality, high amperage inductors for a 1st order crossover. (45hz crossover point) I have never experienced this thus far in my life, when I add one of the subs to the system, I hear very little to no difference in total bass frequencies. When I swap the polarity of the sub, I hear very little to zero difference in total bass frequencies. Is this because my homemade sub has a 1st order crossover and the Olympica IIIs have either a second or fourth order crossover meaning the sub is approximately 90 degrees out of phase to my main speakers? And if so, I assume I would essentially “Fix” the siutuation by instead adding a second order network to my subwoofer? These answers have been impossible to Google! Hopefully you all can help shed some light on this one!