Compatibility between speakers and sub.

The SVS application may show you the lower frequency of your speakers.

Maybe someone at the AVS site can help you with your setting up. In the end when you gain some proficiency your setup will reflect your taste.

The SVS guideline is 10 Hz above whatever the -3 roll off is. They weren’t able to be helpful around addressing the minus six question. Also, this seems as though it’s a bit of an arbitrary call since I’ve seen conflicting information from sources just as reliable, albeit not the brand manufacturing my subs in particular. On their site where they have speaker matching, they suggest that I use 63 Hz, but they have that same number for every single Atc Speaker despite the range of different frequencies, and the 10 Hz above the 48 that SVS told me to do would be 58. Perhaps the difference between 58 and 63, or 70 if I take my guess about where the -3 roll off is not significant. I don’t know. That’s why I’m trying to find out more about this. It makes me insecure that I’m just picking a number out of thin air to some degree here.

get an app and some full spectrum pink noise to measure the f3 at your listening spot,  i bet it will be lower than you think.  

after many years of subs i felt they sounded great most of the time but caused some issues and were only useful with a handful of recordings.  

i am happier with the sound of near full range speakers and a robust amplifier.