Shure V15VxMR to be discontinued

Everything has a resonance, especially an electro-mechanical device such as a tonearm. There's no way around it although the Q of the resonance can be played with. Sean
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Sean would have had my agreement up until the last 10 or 15 years, during which my work involved electromechanical systems including many digital servos. (It was a missile guidance system, and had about a dozen servos of one kind or another, but all digital). Given sensors that are accurate, motors that are strong, and a powerful microprocessor, the dynamic characteristics of the controlled member are entirely (well as close as you could want) a function of the algorithms you design and run. It is as if the actual physical mechanical item, in our case a phono pickup arm, no longer exists, and what does exist is a "phantom" item, which "inhabits" the physical device, but which completely defines its properties. This phantom is defined by the lines of code in the control algorithm, and can be just about anything that the designer wants. Lack of resonance would be one of these desirable properties.

And, for those who don't believe in science but would rather go with what actually works, let me tell you straight out that the servo-controlled arm in the Sony PS-X800 turntable exhibits no resonant behavior at all. I attribute this to the servo design. Do you have another suggestion?

El: One would have to have an equal yet opposite controlled reaction that responded on a phenomenally time sensitive basis in order to cancel the type of resonances that we are discussing here. Given that a tonearm has freedom of movement in both the vertical and horizontal planes that responds on a dynamic basis to the modulated grooves being tracked, and i've never seen an arm that had servo controlled motors responding to and driving an arm in both of those planes simultaneously, i'm pretty sure that the arm on the Sony ( along with all other tonearm / cartridge combo's ) has some type of resonance to it.

The only other approach that i know of to address such a resonance is "fluid damping", which several different advanced design tonearms make use of. Even using such an approach, the resonance is not removed, it is just altered in bandwidth and amplitude ( "Q" ). Sean
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Sean...Believe me, sean, it can be done. Analog implementation of the necessary algorithms was not possible, but digital servos can be absolutely phenominal.

You want "fluid damping"? No problem...just a few lines of code. Oh and what would you like the viscosity of the fluid to be. You can make it anything you want, even far beyond the range of any real fluid. Would you like the viscosity to vary with frequency? No problem. In the real world this is called a "non-Newtonian" fluid, and the only one I am familiar with is tomato catsup. (Viscosity goes down with rate of flow, or as Ogden Nash said...

You shake and shake and shake the bottle.
None will come,
But then a lot'l.

:-)

Recently, Shure has added the following bits to their V15VxMR page regarding the discontinuation of their cartridge -

[[
We regretfully announce discontinuation of our legendary V15VxMR audiophile phonograph cartridge due to scarcity of exotic materials essential in the manufacturing of the VN5xMR stylus. These materials are increasingly difficult and costly to obtain, and substitutions of those materials would compromise the performance standards expected of the V15VxMR.

In keeping with the tradition of the Shure phono line, we attempt to provide replacement styli for at least five years after a cartridge model is discontinued. This V15VxMR cartridge must be discontinued immediately so that remaining VN5xMR styli can be placed into our replacement parts inventory.

We strive to continue offering innovative audio products that provide outstanding performance and value, and apologize for any inconvenience that this may cause.
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-- http://www.shure.com/phono/v15vxmr.html, Sun Nov 28 21:10:11 EST 2004

-eric (who recently just bought one of these)