Need Advice: Vinyl Hum Issue

@lanx0003 

You quoted 

Yes — acoustic feedback is absolutely in play here, and in fact it ties perfectly into the woofer pumping, rattling, and the way the sub changes the behavior.

But my old eyes cannot find this in ChatGPT’s original response, or anywhere else in this thread!  I presume that this was the generated response to a new question like "why didn’t you use the phrase "acoustic feedback".  So thanks for asking this question, as requested, on my behalf.

@viridian noted that:

AI can’t even use the common term "acoustic feedback"?

By the time ChatGPT gave its (his?) second response, lo and behold it included the term "acoustic feedback".

By the way, a decade or so ago, I led a team of IT guys and lawyers to build an application using a legal Expert System.  The primary goal was to assess whether a financial adviser was lawfully able to provide financial advice to a client.

The Expert System (Softlaw) used backwards and forwards chaining inference engines operating on ’facts’.  Softlaw ’facts’ had three potential values - true, false and don’t know.  I introduced a fourth value - haven’t asked yet.  Up to 5000 facts could come into play.

The resulting application was phenomenal at explaining why it reached each assessment, including links to the legislation and regulations.

To all interested, Rega Planar 3 has its ground wire tagged to the signal ground shield of one channel, so it has no “ground wire”.  Like an AR XA/B in that regard.

One question I have…why is OP’s KC62 high level connection to only the L channel?  Does he not care for R channel bass?

A sophisticated sub like this KEF should have a very steep DSP filter to eliminate frequencies below its tuned cutoff, shouldn’t it?  Doesn’t it?

So far as I can tell from a quick scan of recent posts, we still do not know what cartridge was being used in the system as described, AND we do not know whether the symptom goes away when the OP reverts to a bare wire connection. It may make all the difference to do that, but there is also the possibility that the bare wire to spade connector thing is a red herring, that the hum arose coincidentally when the change was made but that the change in connector was not the cause. Also, Grado cartridges, for reasons that are known but which I cannot recall, are particularly prone to hum with the peculiar Rega ground system.

Quick update — the issue is fixed.

Just wanted to follow up in case this helps anyone else. The hum and the woofer/rattle problem are completely gone now. What I ended up doing was removing the spade connectors on the R8 and going back to bare speaker wire, then unplugging and reconnecting the RCA cables between the Alva Duo and the R8. I powered everything down, waited maybe 30 minutes, then turned the system back on. After that, the system is dead silent — no hum, no woofer movement, no rattling, even when I turn the volume up. Not 100% sure which part did it, but my guess is the spades were creating some kind of ground loop with the sub. Either way, switching back to bare wire and reseating everything solved it. Thanks again to everyone who chimed in with suggestions — really appreciate it. 
NOTE: This is me Kevron99 otherwise known as Ron. A human and NOT an AI😊