Cartridge burn-in

Mijostyn, I’m a car guy too, so you need not teach me about flat spotting. Tires are filled with air, which has a lot to do with the phenomenon. So far as I know, cartridges are not filled with air. The subject is irrelevant.

Rubber Compounds are not a predictable material, the environments these are exposed to will impact on the Elastomers properties.

In general, there is a reaction to ambient temperature, if cold the Rubber Compound will reduce in compliance and could be a Hard Substance, alternatively the ambient Temperature being hot, can cause the Rubber Compound to soften, possibly to the point of being too compliant.

The relationship between the Rubber Compound and how it functions as a compliant elastomer, at an interface between the cantilever/generator, especially for allowing freedom of movement for the envelope of dimensions the stylus requires, is critical to the overall performance and designed in qualities for the Cartridge.

The Rubber Compound as said will be multipurpose in function and will manage Vibration being met from varying sources. Resonance coming from the cantilever, is just one. When a Rubber Compound used a Damper is in an environment that enables the Elastomer Properties to be at their optimum, it also serves to be a preventative for the production off micro jitters from the stylus when in contact with the LP. The Rubber Compound functioning as a Damper will also position the cantilever in its proper place, in relation to the optimised interface with the generator.

The Compliance of the Elastomer is measured (compliance units).

Compliance Units is a mathematical equation and is also to be combined with ambient temperature of the environment, as the 'CU' calculation for Rubber Compound with Elastomer Properties is dependent on ambient conditions to apply a standardisation for the equation. One would like to believe when having information like this made known, that the Manufacturer is choosing an Elastomer Property that is falling into the middle area of Temperatures that are expected to be encountered, or the reality is maybe they are not. Maybe they are using a material that yielded the best for the design in a chosen temperature used for testing the design. 

 Revisiting the Tension Wire, that is in general a part used on MC cartridges only. – A typical configuration for the attaching of the Tension Wire is to attach to the Coil local to the Damper at the generator end, and also attach the Wire to the Cantilever local to the Damper.

The Tension Wire can be pulled to create a tension of the coil assembly against the Damper Elastomer. The selection of tension applied, is critical for controlling the activation of the suspension in relation to the mass and tracking force of the cartridge. This adjustment is a critical adjustment when building the cartridge, it may even define the uniqueness of a particular Cartridge from a particular Model within a Brands range of Models.

If the tensioning is dependent on the compliance of the Damper Elastomer, then the tensioning is also dependent on ambient temperature, and if this is not of the correct Celsius, it is most likely the critical parts are not performing in their optimised condition and the mechanical interface of the critical components is also compromised.

It is not too difficult to achieve a consistent Temperature at the location where the Cartridge is in contact with a LP, it is also not too difficult to create an easy to change Temperature between 10 - 30 Degrees Celsius to learn where the critical items might appear to be at their optimised. 

There is more to consider than the accuracy of the electronic interfacing for a Cartridge to an amplification and the Cartridge > Arm Matching. Either of these are standardised and not a concealed science, so these are most likely the least of the concern, when attempting to achieve an overall optimised set up. Creating the optimised environment for the Critical Parts that enable the Cartridge to function, that takes a little more wizardry.    

Unfortunately, I don't see a Manufacturer revealing the 'Dyne Calculation' for the 'CU' of the Elastomer or inform on the optimised ambient environment, there might be a little too much 'IP' in that as reveal.

If of interest the above does possibly share a Place with Car Tyres and their Compounds Elastomer Properties.    

I have never in my life become accustomed to any kind of audio harshness. 

I could have saved lots of money if that were true.   

This idea needs to be banished once and for all.  

With respect to cartridges- think about it.  It is a vibrating tuning fork like object connected to a voltage generator.  

The simple act of burnishing the newly cut sharp surfaces of the stylus with repeated plays should affect the way it reacts and vibrates in the grooves- for the better.  

Thanks to the suspension in all its parts and complexity the stylus/cantilever ought to act like a tuning fork only when excited at its resonant frequency, which response ought to be rapidly damped. Else we’re not going to have music.