Establishing Proper Torque on Cartridge Screws

The AnalogMagik Torque Driver Kit

(Discontinued - No Longer Available)

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

Why do we need proper Torque?

When securing your cartridge onto the headshell or tonearm, it is important to achieve a proper Torque level on the cartridge headshell screws.

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 affects the frequency response, resonant frequency, harmonic distortion, as well as the as well as inter-modulation distortion levels of the generated signal.

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 an increase in 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 tests, 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 (e.g., Titanium vs. Aluminum Screws).

The optimal torque level is one that is tight enough to secure the cartridge but not overly close to the point where it starts to affect the resonance frequency as well as the frequency response of the cartridge.

The "Stiction" Phenomenon

& Custom 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. Base on our finding, we find TEFLON to be far superior for our application. Nylon's friction coefficient is not as good as Teflon to provide for the accurate torque level required.

AnalogMagik's custom made Teflon (PTFE) washers are non-standard sized, custom made to our specification. It provides 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.

Preset vs Fixed Torque Drivers

A torque drive is a precision tool with an internal mechanism that 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 superior to others. 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 that 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 more significant effect than the variation caused by different materials. In other words, it is more important to have the proper Teflon Washers than to have a variable torque driver.

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

(Note: Calibration warranty is 3 months. Mechanical warranty on breakage or malfunction, 1 yr from date of purchase. Both warranties are provided for by the original equipment manufacturer, not AnalogMagik.)