XV-1S and Antiskate

Doug:
In most MC cartridges, the coil former and coils are located at the rear end of the cantilever, and are always being pressed into the dampers. Since the amount of pressure affects things like tracking and frequency response, it is the cartridge builder who sets the net pressure (during the building and adjustment process), and the pressure adjustment is locked down by screws so that the value cannot be reduced (or increased) inadvertently. If it does become reduced, chances are that the cartridge will ride too close to the LP surface (low-rider).

Due to the constant pressure between coils and dampers, "slower rise times" and "attenuated amplitudes" simply describe how most MC cartridges work normally. These are not issues that suddenly appear because the user happens to choose antiskating or VTF values that are higher than optimal.

What excess antiskating can do is cause uneven loading of the stylus profile within the LP groove, angular misalignment of the coil former and imbalances in the forces that act on the same. The antiskating effects manifest themselves in the horizontal plane.

Doug, I agree with you that improper VTF is conceptually similar to improper anti-skating. What's different is that, unlike AS, we need a minimum level of VTF to ensure adequate physical tracking of the groove (but uneven stylus loading in the LP groove is no longer an issue). And since VTF forces are typically 5-10 time higher than AS, compared to AS we get a far greater degree of angular misalignment of the coil former and imbalances in the forces that act on the same. And, it is in the vertical plane that we see the effects.

As problems to be solved, AS is far more intractable than VTF. VTF requirements don't change across the LP, so it is possible to understand in advance what value works best and specify this (although changes in ambient temperature and humidity may require some readjustments). In contrast, AS requirements change according to the LP groove radius and groove drag (caused by groove modulation and stylus profile). It is possible to solve the groove radius issue, but the groove drag issue is more doubtful, unless you are using a linear tracking arm or some kind of electronic servo arm.

I suggest that it is much easier to speak of a "right" and "wrong" VTF setting than AS.

cheers, jonathan

Hi Doug, all:

A bit more explanation on damping inside the cartridge. There is a significant difference between the damping that the cartridge builder applies, and the damping that the user applies during normal playback (including VTF and AS).

Please allow me refer to the following drawing. Sorry for using one of my drawings, but I want to illustrate the difference between pivoted vs linear damper compression, which most drawings don't do. (The same drawing is on our website, but it's a little small and therefore suspension and damper details are hard to see)

http://www.evmag.fr/site.php?page=news97

When the cartridge craftsman adjusts the damper(s) during the building process, he moves the cantilever assembly longitudinally back and forth until he achieves the appropriate amount of damper compression (and therefore damping characteristics).

The suspension wire fits into a larger rod (called the stopper pipe), and this stopper can move back and forth inside a matching tunnel which is drilled into either the magnet (in the case of yokeless designs) or the rear/center polepiece (in the case of conventional designs). The tunnel is drilled so that it is parallel to the stopper pipe (therefore perpendicular to the length axis of the rear polepiece). Usually, the polepiece is fitted with a grub screw to enable the craftsman to lock the stopper pipe in place once the desired damping point has been reached.

The damper(s) are sandwiched and compressed between the coil former and rear polepiece, and it is the degree of compression that defines the total damping amount. Since the stopper pipe can only move longitudinally within the matching tunnel, you can visualize that, when the cartridge craftsman adjusts the damping, the dampers are compressed evenly across their entire surface. IOW, when the cartridge craftsman adjust the dampers, the total amount of damper compression and therefore damping changes substantially.

However, damping that the user applies via VTF and AS during normal playback is a different issue. Again if you refer to my cartridge cross-section drawing, you may note that, when VTF is applied to a conventional cartridge, the cantilever and coil former appear to be angled in comparison to the rear polepiece. This is because the cantilever and coil former are rotating around a pivot point.

The suspension wire is enclosed along nearly its entire length - inside the solidness of the cantilever at the front, and within the (again solid) stopper pipe at the rear. The only place where the suspension wire is unenclosed is a very short length either inside the coil former or right behind it. This place is called the suspension pivot point, and here and here only the suspension wire is free to move.

When the user applies VTF and AS during normal playback, the coil former rotates around the suspension pivot point, altering the distribution of compression on the damper(s) sandwiched between the former and rear polepiece. But since the movement of the coil former is rotary rather than longitudinal, when one section of the damper(s) is more heavily compressed, the section 180 degrees across it will be unloaded by the same amount. The relation is like a see-saw - when one side of the damper become more compressed because the cantilever is forcing the coil former more heavily into it, the other side of the damper becomes less heavily loaded. The total amount of damper compression doesn't change, because any increase in damper compression on one side is counteracted by less compression on the other.

Your analogy with the Land Rover (nice car!) is different than an MC cartridge, because with cars the damper and suspension preloading incorporated by the manufacturer occurs in the same axis as the loading applied by the user. With MC cartridges the damper suspension preloading incorporated by the manufacturer is longitudinal and therefore affects the total amount of damping, while the loading applied by the user occurs in the form of rotation (see-saw), and total changes in damper compression will be far less.

However, Doug, none of the above means that I am critiquing your post. After accounting for the above explanation, we are left with a couple of residual effects which may help to explain why we hear changes with VTF and AS (and I concur that we do). These would include progressive or non-linear characteristics of the damper(s), mis-orientation of the coils, and motional non-linearities due to mis-orientation of the coil former (although the last factor should only affect permeable rather than non-permeable formers).

kind regards, jonathan