Subwoofer rumble issue

Wow! This sounds like what happened to me few weeks ago when I moved my equipment around, the higher the volume goes the more rumbles the sub makes. The Preamp and the Phono-Stage Preamp originally were in the same cabinet, w/i 3' from each other. The problem happened after I moved them apart almost 3 times of that distance. I believed the fix was moving both equipment back in the original position. You might also want to look into the cable orientation relative to each other, like power cables and interconnects should be crossed instead of parallel. Good luck in your troubleshooting. 

Hey thanks! 

Glad to hear you got it worked out and thanks for sharing the solution. 

Subsonic rumble filter! All better! I understand it’s a “bandaid” approach but it totally worked and my stereo sounds amazing again! YES!!! Thanks again everyone!

Yes until you figure out how to stop the airborn feedback, it is a band aid, as it’s taking away what stereo info there is below 140hz
Quote: "The circuit "monos" the low frequencies below 140 Hz"
I still don’t understand how this will fix the airborn feedback test I asked you to do though, did you try it again with this filter in place?

Cheers George

Yeah I hear ya. I also built an isolation platform out of two butcher blocks. I sandwiched it with gel furniture pad discs. I wonder if that is contributing to the solution more then the rumble filter. I’ll remove the filter when I get home and give it a shot.