I don't own a Dyna, but Raul provides a plausible explanation for some reviewers' preference for higher than recommended VTF's. Reviewers listen to new cartridges. New elastomers contain molecular bonds which prevent a smoothly linear compression. Once the elastomer "relaxes" a bit, from use, the cantilever can accelerate smoother, faster and reach fuller extensions. Design range VTFs now allow the cartridge to react more linearly to groove modulations - especially small, HF ones. This is why the last sonic change during cartridge break in is typically a reduction in HF "grain". The elastomer is finally allowing a smooth response for even the smallest movements.
Thom's observations are spot on, though I think he gives me too much credit. Anyone who lives with high performance cartridges learns how sensitive they are to small adjustments. With our best cartridge, the VTF window for acceptable performance is never more than .04g wide. The window for prime performance is about .01g wide. Larger adjustments bounce us right out of the zone.
As Thom said, these subtle changes have little to do with tracking/mistracking or keeping the cantilever centered in the magnetic fields. VTF has to be badly off before you have those problems. The ideal VTF is one that maintains constant stylus-groove contact while putting the LEAST external pressure on the suspension. The more pre-compressed the elastomer is, the less it can can compress when the cantilever tries to move.
In a sense the "ideal" VTF is a lot like the "ideal" antiskate setting: you want the minimum force necessary for the job. This allows the cantilever/elastomer the greatest freedom to respond quickly and fully to groove modulations. External pressures, whether downforce or sideforce, inhibit this freedom and muffle the sound. Lateral fluid damping of the arm has the same effect and for the same reason - at least on a TriPlanar with any cartridge we've used. That feature may have been a useful bandaid with the peaky MC's that were prevalent when Herb Papier first offered it, but it is not needed with modern MC cartridges.
Thom's observations are spot on, though I think he gives me too much credit. Anyone who lives with high performance cartridges learns how sensitive they are to small adjustments. With our best cartridge, the VTF window for acceptable performance is never more than .04g wide. The window for prime performance is about .01g wide. Larger adjustments bounce us right out of the zone.
As Thom said, these subtle changes have little to do with tracking/mistracking or keeping the cantilever centered in the magnetic fields. VTF has to be badly off before you have those problems. The ideal VTF is one that maintains constant stylus-groove contact while putting the LEAST external pressure on the suspension. The more pre-compressed the elastomer is, the less it can can compress when the cantilever tries to move.
In a sense the "ideal" VTF is a lot like the "ideal" antiskate setting: you want the minimum force necessary for the job. This allows the cantilever/elastomer the greatest freedom to respond quickly and fully to groove modulations. External pressures, whether downforce or sideforce, inhibit this freedom and muffle the sound. Lateral fluid damping of the arm has the same effect and for the same reason - at least on a TriPlanar with any cartridge we've used. That feature may have been a useful bandaid with the peaky MC's that were prevalent when Herb Papier first offered it, but it is not needed with modern MC cartridges.