Cartridge burn-in

The only item in the assembly that is looking likely to need to show a change that is perceived as adding an improvement through the change is the Material used for Damper.

A Change to the Stylus is potentially wear only and this will be deemed detrimental as it progresses.

The Cantilever and Pivot are certainly not parts belonging to the assembly that would be wanted to change their inherent properties.

The Damper is a material that is a Compound of materials that will ultimately become a Type of Rubber, the constituents/formulations will vary to produce the Rubber Compound. Designers will select a substance that in many cases will be a unique material, that satisfies the designers need for the elastic and viscous properties of the material, and possibly the known environmental effect on the Compound.

The Rubber Compound selected as the Part, can have a multiple of ingredients and these can vary in the parts added per 100 parts of rubber. The final selection of the Rubber Compound and effects on the Compound of the added Elastomers will undoubtedly produce a Part, when selected that is to have a multifunction role.

One such role which will be for the managing of vibration will be best served from a Compound that has the correct Static and Dynamic Properties engineered into the Rubber Compound. Knowing such information will be critical in the selection process.

It does seem that a Damper is to change its properties through usage and possibly time. It does seem a most likely Damper Selection will be limited to a selected few, who will be qualified in making the choices for these changing in properties materials. 

It does seem a Damper has the potential to be impacted on by the environment it resides in, and through usage can change. It also seems likely a Damper that has been exposed to the environment/working environment for a long period can possibly undergo changes that become detrimental to the Cartridges performance. The question is do Dampers from a production have a uniform property or is there variances across samples, or is there Dampers used that might already be affected by the environment they are kept in. Is this a possibility a Quality Control issue and is contributing to the differences reported for Break In times. 

It is possibly a selection of a Damper Material, that is one, that can make or break a Design and how it is received in the Market Place, so a very big responsibility to get it correct for the end user. Keeping a Damper material as stock item for an extended period in a particular environment might have an effect on the material and change the performance of product as it produced over a period of time.

The Suspension is one I am not sure of, it is known to change its properties through usage, but I am not sure where the detriment to the overall performance manifests due to these changes. It is not uncommon to see a report where a Suspension required re-tensioning, the question is does the tensioning vary between models when new. Is this a quality control issue and can possibility be contributing to the differences reported for Break In times. 

@lewm, flat spotting will occur in high performance tires if left parked for 30 minutes. As the tire cools down it hardens and loses traction. The colder the ambient temperature and the surface the tire is on the faster this occurs. This why tire warmers are used in racing. A cartridge's suspension undoubtedly heats up to some degree and obviously at rest it cools down in a position other than what it is in while playing a record. A theory based on assumption. May not be true at all but it is imminently plausible. On the other hand, I do not hear it. I did not hear the MSL change at all during the first 50 hours but @sksos did in an MSL that is almost identical.  So either my hearing is not good enough to discern the difference or break-in is a psychological phenomenon. Take your pick. I think you would agree that if a cartridge breaks-in the difference between new and say 100 hours is not night and day but incremental at best.   

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.