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Tonearm microphonics

When I have the volume at my normal level & tap the arm (not whilst playing vinyl) it is slightly amplified... Is it possible to significantly reduce/eliminate this?

Current set up - Roksan Xerxes 20plus, Origin Live Encounter tonearm (thin cork ring at the base) with Lyra Skala.

Apologies if this is a stupid question!
infection
bdp24's avatar
bdp24
10,254 posts
 
To clarify, the relationship between warp and eccentricity demands on the ability of the arm to follow them, and the frequencies involved in those demands, are a matter of the time it takes the arm's headshell to traverse a warp or eccentricity. If a warp takes the arm's headshell a full second to travel up and then back down, the frequency involved is 1Hz. The same for an eccentricity that it takes the headshell a second to follow left and then right, back to where it started; one second equals 1Hz. If the warp or eccentricity take 0.5 seconds to traverse, the frequency is 2Hz, and so on.
timeltel's avatar
timeltel
830 posts
 
Regards.

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, airborne or mechanical. Constructive resonances are typically considered to primarily fall in either the fifth harmonic or at the first octave, The enhancement of these resonances are usually considered pleasant, sometimes even desirable (think piano or strings). Destructive resonances may be generated by extraneous mechanical vibration or reflected airborne energy such as sound reflected from walls, a nearby speaker or other objects close by. This may also be described as  proximity resonance.  

Sources of these resonances can be autonomous, sometimes described in terms of Eigen value. Imagine a large, heavy plinth coupled to a light tonearm. If the plinth is energized it will act on the tonearm to some commensurate degree. The tonearm resonates to it's own value. When these resonances couple to resonate in phase and not disproportionate to the recorded signal these resonances may be said by some listeners to be considered as desirable.

Resonances not in phase are said to be destructive. In this sense and depending on degree, damping can generate either constructive or destructive resonances.

Just when one thinks they've a handle on the phenomena and your turntable is performing in a wonderfully synergistic manner, a change of cartridge or headshell shifts mass, nodes are redistributed, phase goes out of kilter and unanticipated boundary resonances return unwanted signals.

The cartridge doesn't care where the signal comes from.


Peace,


  



moonglum
619 posts
 

Dear Bdp24,

Sincere thanks for your excellent and well written post.

I knew that if we “mechanical laymen” poked the problem with a stick for long enough, someone would weigh in with some actual research ;)

I had completely forgotten about the Rock. It is one of the most well-researched turntables in analogue history. If Townsend says that damping works regardless of adverse conditions then that’s good enough for me. :)

Best regards,

Bill.

larryi
4,334 posts
 

If I understand how viscous damping works, resistance increases with velocity of movement.  As an example, if you put your hand in water and move it very slowly, there is very little resistance to movement.  But, try to move it fast, and the resistance increases dramatically.  When a tone arm has to make large lateral movements (e.g., off center record) , it is forced to move at a much higher velocity than its normal movement, which is quite slow.  I don't know if this added resistance is enough to create excessive strain on the cantilever or the suspension, but, I would guess that fluid damping is not a help in these situations. 

But, some resistance to movement laterally might be a help when it comes to bass response.  Deep bass is often cut monophonically so that all of the movement is laterally.  If the movement is large enough, the whole arm will move instead of the arm being held steady (stead would mean all of the movement of the cantilever is translated into signal).  Thus, movement of the arm to follow the groove results in reduced bass response.  If damping helps to resist such movement, bass response would be more powerful and faithful to the signal on the record.  The Moerch DP9 anisotropic arm does this by increasing the effective mass of the arm in the lateral plane of movement; I bet damping would provide similar resistance as well.

rauliruegas
13,129 posts
 
Dear @larryi : You are rigth about that " resistance " that more than affect the cantilever could " affect " suspension but I think maybe not something to worry about and when this " trade-off ( that we don't know for sure it's a real trade-off. ) goes infavor of that better bass response then we have to go a head with. Remember that the foundation of music belongs to that frequency range.

In the other side the huge forces generated at stylus tip/grooves are of different kind and till we can measure we just can't know if that resistance is really " dangerous ". Could be that's compensated " some way ", maybe not but that kind of damping is welcomed because its virtues in favor of MUSIC.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.
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