@oddiofyl Every Velodyne sub of that Era will fail. I sent my Dad's plate Amp on his HGS 10 to EBC in NJ about 5 years ago and it's been great since.
If this were the case I would expect far more original owner failure conformation. I replaced an M&K Volkswoofer with a Velodyne ULD-18 in 1983 followed by their F-1800 in 1995, HGS in 1998, DD in 2003 and two DD-12 Plus in 2011 still in service. My only service issue, Velodyne replaced $32 infrared receiver in my second owner out of warrantee Plus, minus the labor and threw in a new remote control for free.
@gotolondon2 ...if you are using the DSP on the Velo, you should stop. I could only get that sub to sound right the old fashioned manual way.
What did your dealer say about remedying this issue?
@kraftwerkturbo FYI, REL are -6dB Sub-Bass Systems. They're extra low frequency output is rolled off to a point so as not to excite a rooms standing wave bass modes.
DSP implementation varies greatly.