"When securing your cartridge onto the headshell or tonearm, it is important to achieve a proper Torque level on the cartridge headshell screws. We have consulted with a dozen of cartridge manufacturers, and found many of them to have not done any research on the effects of proper Torque and its effect on the audio signal. Of all the manufacturers we contacted with, only 2 replied to us, offering insights on the effects of a proper torque level. One came back with some sort of scientific backings. In other words, not too many people have really looked into this except us. There are also a lot of misinformation on the proper torque level.  One Torque tool we found on the market has a setting so high that it will crack the body of ZYX cartridges." 

In conjunction with SEM Powertrain Engineering, AnalogMagik has performed extensive research, measurement and listening tests on the effects of proper Torque on the headshell screws and the resultant sound of the cartridge.  

On a microscopic level, the torque on the headshell screws affect the frequency response, resonant frequency, harmonic distortion, as well as the as well as the inter-modulation distortion levels of the generated signal.  Many of these measurements require sophisticated measuring equipment way beyond the scope of the AnalogMagik software.  Thanks to SEM Powertrain Engineering, we have such equipment in-house, readily available at our disposal.   We have done the hard work so that you don't have to.

If the torque is too tight, it will change the resonance frequency of your setup, acting as an unwanted equalizer, contaminating the audio signal.  It will lead to a reduction in the high frequency response, as well as causing an increase to the level of inter-modulation distortions in the low frequency region.    Sonically, this translates to a sound with smothered ambiance and "air", while instruments will be robbed of natural decay and resonance.

If the torque is too loose, the cartridge will come loose.    

Through hundreds of hours of measurement, trial and error, and listening test, we have discovered the optimal torque level is between 0.60 inch lbs to 0.70 inch lbs, with a slight variation when using different materials (eg. Titanium vs Aluminum Screws).  It is a torque level which is tight enough to secure the cartridge, but not overly tight to the point where it starts to affect the resonance frequency as well as frequency response of the cartridge - the optimal level in our opinion.

The "Stiction" Phenomenon & PTFE Teflon Washers

Logically, one might expect the difference in material will require a different torque level?      This is true assuming you can achieve a precise level of torque in the first place.

The trick, however, lies with the "washer".    We have discovered that stick-slip phenomenon (Stiction), imposes a greater effect on achieving proper torque, than the variation of torque level between different materials choices.

Without a proper Washer in between the Screw and the Headshell, the roughness of the material surface (metal screw rubbing against metal headshell) will not permit a proper torque level to be achieved.   Most manufacturers provide Nylon washers to mitigate this problem, but nylon compress over time, and its friction coefficient is not as good as Teflon..

AnalogMagik has discovered that Teflon (PTFE) washers provides for a much better friction co-efficient to allow for a precise torque level down to nearly 0.01 inch lbs.   It also mitigates the effects caused by material variations.      

However, nobody uses Teflon Washers, and for the size we need it is very hard to find, so we decided to make our own !   

Preset vs Fixed Torque Drivers
A torque drive is a precision tool with an internal mechanism which will prevent the driver from turning further when the proper torque level has been achieved.  Not all Torque Drivers are equal.  Some will come to a hard stop, some will click, and some will disengage very gently to provide an optimal torque level more superior to others.    We have looked at all the Torque drivers on the market and we have found one with the highest quality.

The are two types of Torque Drivers, Variable and Fixed Torque.      

Variable Torque drivers typically cost 2x as much as a fixed torque driver.   It has the advantage where users can experiment with different torque levels.     However, they tend to go out of calibration very quickly, and the level of accuracy is not as good as fixed torque drivers. We have also discovered that it is more important to have the proper washer because the mitigated stick-slip phenomenon has a bigger effect. 

Therefore, AnalogMagik has decided to provide a fixed torque driver for our kit.  The torque is preset at a level which we believe should be good enough for 90% of the cartridges on the market. 

The AnalogMagik Torque Driver Kit comes with:

1) Preset Torque Driver - Precision calibrated with Precision Guarantee Certificate
2) Two drive bits (slot and hex), suitable for 90% of cartridge screws
3) 4 Custom made PTFE Teflon Washers