Hi Neil - Without seeing what's going on first-hand, I can only offer up the following:
First of all the channel drop off - interesting you bring this up as I experienced this with one of my previous project tables. Most notably the "fix" you mentioned was exactly what I did as well - what turned out to solve this for me was switching out the cables from the TT to the phono stage. All I can guess is that the email connectors on the project were too large in diameter and weren't always making a connection. I've since moved up the Pro-Ject food chain and haven't seen the problem since.
The rumble could take more troubleshooting and my suggestions are based on an assumption (not clear from your post) that it's happening even w/ no music playing correct?
If so, I'm going to guess that it's low frequency resonance between the tonearm and your subwoofer at the arm's resonant frequency below 20Hz. An easy test would be to turn off the LF filter on your phono stage, and with the volume up (nothing playing) go thump on your table with the sub on versus off and see if that makes a difference.
If you find that it is your sub, then I would either opt A) not to use it when playing records B) adjust it so it doesn't interfere with the tonearm C) try better isolation for the turntable itself which is always a good idea anyway
Good luck
Greg
First of all the channel drop off - interesting you bring this up as I experienced this with one of my previous project tables. Most notably the "fix" you mentioned was exactly what I did as well - what turned out to solve this for me was switching out the cables from the TT to the phono stage. All I can guess is that the email connectors on the project were too large in diameter and weren't always making a connection. I've since moved up the Pro-Ject food chain and haven't seen the problem since.
The rumble could take more troubleshooting and my suggestions are based on an assumption (not clear from your post) that it's happening even w/ no music playing correct?
If so, I'm going to guess that it's low frequency resonance between the tonearm and your subwoofer at the arm's resonant frequency below 20Hz. An easy test would be to turn off the LF filter on your phono stage, and with the volume up (nothing playing) go thump on your table with the sub on versus off and see if that makes a difference.
If you find that it is your sub, then I would either opt A) not to use it when playing records B) adjust it so it doesn't interfere with the tonearm C) try better isolation for the turntable itself which is always a good idea anyway
Good luck
Greg