I think the whole 6Hz resonance thing is a red herring
Thanks, agreed if you are looking for tonearm / cartridge resonance! I realised last night that it is almost certainly caused by sub-plinth resonance instead.
Now I know that, if I were at home, I could just play the Tacet record louder and find out where the arm resonances are. The only instrument I am using with this record is my ear.
I am assuming the Tacet record relies on acoustic feedback to excite the resonance, which has to be big enough to cause audible mis-tracking? But @billstevenson has caused me to query this assumption?
I am glad the problem is at least ameliorated
The only thing that has changed so far, is that I think that adding downforce makes one record sound slightly cleaner (the music, not the noise) but I doubt if I could pick it in an A/B comparison. Long term, I don't want to keep running an expensive cartridge at 150% of its recommended tracking force.
My original question about varying rumble-like noises from some classical records is still open ![]()

