Tonearm microphonics

Correct me if I'm wrong, I really don't mind. A cartridge doesn't care where it's signal comes from and if any constituent part of a turntable can resonate, it will. Resonance can be either constructive or destructive

@timeltel,  I respectfully ask you to look up the definition of resonance as it relates to vibrations.  It is a condition that increases the amplitude of vibration greatly and as such cannot be constructive.  What's worse is you are using a mechanism where a vibrating stylus is used to reproduce the recorded sound.  If you care at all about accuracy in sound, you do not want a resonance in the audio band. 

Regards, rotarius:

Thanks for the considerate manner of your post. Please consider: "Constructive" and "Desirable" are not necessarily synonyms.

First, neither are resonance or interference technically the same. However, when considering transducers sometimes resonance can generate interference.

Here're a couple of relatively easy to grasp descriptions from:  

Frank Heile, P.h.D. Physics, Stanford University (quote):  
"Resonance is when a driving force is at a frequency that is close to the natural oscillation frequency of a system. This makes the amplitude of the oscillation of the system greatly increase.

Interference is when two waves at similar frequencies are superimposed which results in either constructive interference when the waves are in phase and add together, or destructive interference when the waves are out of phase and interfere with each other."

And:

Bruce Thompson, former Computer programmer at University of California, Berkeley:
"In some systems it makes sense to use either "interference" or "resonance" to describe what is happening. For example in a trumpet, the waves created by the vibration of the player's lips interfere constructively, creating a resonance effect."

 In a paper presented to the AES, Shure technician C. A. Anderson states:
"Resonance exists because the arm and pickup assembly behaves like an effective mass that is coupled to the record groove by means of a stylus assembly with its own mass, compliance, and mechanical resistance".

If a 1kHz signal recorded to vinyl represents a displacement of 80 microns (according to a study by St. Andrews College), it would be difficult to argue that unwanted vibrations of the tonearm have no influence on the signal. The cantilever doesn't discriminate from which end movement originates, sometimes the tail DOES wag the dog.  ;-)  

When a recorded signal matches the natural resonance of our tonearm/cartridge, Mr. Anderson states the recorded signal can be enhanced by 6 to 20 dBl. He doesn't state such but with out of phase  resonances then distortion, diminution or even cancellation of signal at specific frequencies might be anticipated. Resonances can then be considered as constructive or destructive.


Poem.
by Henry Gibson

Her name was Grace, she was one of the best,
Late last night I put her to the test.
She looked so sweet, pretty and slim.
The night was quiet and the lights were dim.
I set everything up as nicely as I could.
I handled her gently for I knew she was good.
She was just one big thrill and the best in the land.
Then she hummed but it was not for joy.
More effective damping was obviously in demand.

Peace,

Sometimes I forget this is not a technical forum.  I realize in the audiophile world things are a bit different from the plain ol' vibrations from electrical and mechanical components I have been dealing with for the last 20 years.  By all means enjoy your constructive resonance.
Cheers.

Infection what I have done is used some of the plumbers teflon tape and wrapped the arm tube. It improved the sound so I left it. I would try that. If it sounds worse remove it or some of it. 
And Raul is right. It is like a microphone and I wouldn't lose too much sleep, tapping on the arm tube while at rest is no indication of how the arm will sound. In fact generally I have found that the better cartridges  are worse for this as they are more sensitive. I have a VDH Colibri that will pick up a fly walking on the arm tube at rest. It sounds fantastic. Higher compliance carts are worse than low for this but that is the same  feature that makes them so detailed and sound so great. 

Dear @handymann : You are using those subwoofers as bass re-inforcement, your call but is not the way to use it and I can tell you that the gentlemans that gave you that kind of advise were and are totally wrong.

You need high-pass filter  for you can use those subwoofers along the Wilson speakers in the correct way. Till you make that kind of set up you can't know what you could need.

My advise is to do it and stop to think on that room treatment of 15 hz filter that only makes a signal degradations.

The " ball " is in your field.

regards and enjoy the MUSIC NOT DISTORTIONS,
R.