There is no best cantilever material per se.
The selection of cantilever material and construct will depend on what the designer is trying to achieve with their particular cartridge design.
Typically the designer will want avery stiff cantilever material in order to push the mechanical resonance of the stylus/cantilever as far above the audible frequency range as possible, but they will also want low mass and low effective tip mass on the stylus. The original method of calculating tip mass was a derivation from the resonant frequency, i.e. the higher the resonant frequency the lower the tip mass.
Now here is the kicker - if you factor in not just stiffness, but mass to stiffness then the material itself is only one part of the equation. For example a hollow pipe will typically have a mass to stiffness ratio 6 times higher than a solid rod.
In the Shure V15vxmr they used micro walled beryllium tube specifically to achieve the lowest effective mass and highest RATIO of mass to stiffness..
This high resonance results in low effective tip mass providing better tracking and cleaner high frequency response.
The Technics EPC100 was another example where they used extremely thin walled Boron tube to achieve low effective tip mass and response out to 100k. The manufacturing process for the Technics EPC100 cantilever was to vapour deposit boron onto an aluminium tube and then to remove the aluminium by dissolving it leaving an impossibly thin walled tapered tube. As far as I am aware this process is no longer available due to toxicity and safety issues.
I have seen over the years Boron cantilevers in both rod and pipe form, so you need to be specific. A good example of cantilever types is the Sumiko Talisman range which I used to sell in the 80’s - the Sapphire tube cantilever was the "top" model, the Boron tube cantilever was their 2nd tier model, the aluminium cantilever the lowest. Sumiko describes their cantilever choice as follows
The key point from my posts is that in this forum audiophiles often look for a magic bullet - which is better this material or that, tubes for solid state, direct drive or rim drive or belt drive.
The best answer for any competent engineer to these questions should always be "that depends" - engineering choices are almost always in the context of the overall design, purpose and constraints. Believe it or not cartridge designers often have quite different priorities in mind when designing cartridges, trading off extended response for tracking ability, low distortion, long term stability, wear, and many other factors including ( ug ) cost, just to name a few.
The selection of cantilever material and construct will depend on what the designer is trying to achieve with their particular cartridge design.
Typically the designer will want avery stiff cantilever material in order to push the mechanical resonance of the stylus/cantilever as far above the audible frequency range as possible, but they will also want low mass and low effective tip mass on the stylus. The original method of calculating tip mass was a derivation from the resonant frequency, i.e. the higher the resonant frequency the lower the tip mass.
Now here is the kicker - if you factor in not just stiffness, but mass to stiffness then the material itself is only one part of the equation. For example a hollow pipe will typically have a mass to stiffness ratio 6 times higher than a solid rod.
In the Shure V15vxmr they used micro walled beryllium tube specifically to achieve the lowest effective mass and highest RATIO of mass to stiffness..
The ultra-thin (0.0005-inch) beryllium MICROWALL/Be tube, shown in Figure 1c, has the lowest effective mass and highest ratio of stiffness to mass of any stylus cantilever ever,The Shure has a mechanical resonance of 33khz. I believe my Dynavector Karat Nova 13D with its 1.3mm diamond cantilever has a mechanical resonance approaching 100khz.
This high resonance results in low effective tip mass providing better tracking and cleaner high frequency response.
The Technics EPC100 was another example where they used extremely thin walled Boron tube to achieve low effective tip mass and response out to 100k. The manufacturing process for the Technics EPC100 cantilever was to vapour deposit boron onto an aluminium tube and then to remove the aluminium by dissolving it leaving an impossibly thin walled tapered tube. As far as I am aware this process is no longer available due to toxicity and safety issues.
I have seen over the years Boron cantilevers in both rod and pipe form, so you need to be specific. A good example of cantilever types is the Sumiko Talisman range which I used to sell in the 80’s - the Sapphire tube cantilever was the "top" model, the Boron tube cantilever was their 2nd tier model, the aluminium cantilever the lowest. Sumiko describes their cantilever choice as follows
Sapphire Tube Cantilever - second in hardness only to diamond, the low mass Sapphire tube assures quickest transients with virtually perfect phase and non resonant characteristics due to lack of flexion.I also note from their blurb they differentiate between nude mounted diamond with the Boron cantilever and laser mounted diamond with the Sapphire diamond - so maybe this suggests there may be manufacturing benefits from the use of Sapphire at that time - 80’s.
Boron Tube Cantilever - lowest mass with highest rigidity coefficient.
The key point from my posts is that in this forum audiophiles often look for a magic bullet - which is better this material or that, tubes for solid state, direct drive or rim drive or belt drive.
The best answer for any competent engineer to these questions should always be "that depends" - engineering choices are almost always in the context of the overall design, purpose and constraints. Believe it or not cartridge designers often have quite different priorities in mind when designing cartridges, trading off extended response for tracking ability, low distortion, long term stability, wear, and many other factors including ( ug ) cost, just to name a few.