Inner groove "Rumble"


All of a sudden, I'm hearing a weird "rumbling" once the stylus reaches the last inch or so of a record. There has been no sudden "trauma" to my table or tonearm. The first 80 % of each LP side still sounds absolutely fine. Any thoughts as to what's happening here ?
adam18
It's definitely not a "hum." The interference is a very irregular "staccato-like" popping type of rumble, which is now starting to bother me even at the outer grooves of a record. I removed and replaced the belt, moved the sub-platter up and down a few times within the bearing, checked the cartridge wire leads, checked the anti-skate, removed - cleaned - re-plugged the phono interconnects, ...... and still the problem continues, now anywhere along an LP's surface. Oy Vey !!
"staccato-like popping" Can you guess in what frequency range? Rumble is very low frequency stuff, as the name suggests.
Once my ground wire fell off and I heard "popping" noises. As a record spins, a static charge builds up on the vinyl surface. Normally it would flow to the spindle, which is connected to the chassis ground and out. In the absence of a path to ground, the static would discharge to the cartridge itself. In your case I think it's a coincidence that it occurs as the cartridge nears the spindle, the record has been spinning for 10 to 15 minutes building up more static electricity with each revolution.
Check your ground wire.
Rich