JMW 10.5 arm / v.d.H. Frog set-up parameters

I use a van den Hul Frog cartridge mounted in a V.P.I. JMW 10.5 arm on a standard Aries turntable, and seek advice about set-up parameters, and in particular, about V.T.A. set-up.

My cartridge was installed by an installer experienced with cartridge set-up, and my turntable has been carefully leveled as measured from the platter surface. I am not much of a tweeker and have resisted the temptation to mess around with any of the set-up parameters since the cartridge was installed over two years ago, but, as the vertical tracking angle can be varied easily with the JMW arm and then returned to its initial setting, I spent the last few nights trying different settings. The installer had the pivot-end up somewhat, the arm tube sloping down slightly toward the cartridge. I brought the arm down to where it is level with the platter, which took +/- four revolutions of the VTA tower and constituted nearly a 1/4" drop in arm height at the pivot (as estimated from vertical movement of the arm base stabilizer post, which I had suspended underneath the arm cradle for purposes of making VTA adjustments).

Moving the arm up and down within this range brought surprisingly subtle changes. Compared to the original arm height, having the arm level with the platter seems to produce a very slightly fuller sound, with very slightly less well-defined images and a somewhat more diffuse center image. Raising the arm back up to the position it was set at by the installer restores the imaging and center image, and seems to take away just a touch of body compared to the level position. I ended up returning the arm to the original, installer-set, position.

I also removed some silicone from the pivot well and now have a silicone level that is +/- 1/4th to 1/3rd full (3/4ths full is the recommended starting point). This seems to have made a more audible difference, yielding a somewhat more lithe presentation which is pleasing to me. As for effects of the weather on the silicone levels, the ambient temperature in my listening room is +/- 70 F. (21 C.)

Nothing I did to the arm over the weekend radically altered the sound or audibly increased distortion.

I know that azimuth and VTA are said to be crucial to proper performance with the v.d.H. cartridges due to the line-contact shape of the stylus (the smaller "v" represented by the shape of the stylus has to be positioned just right to fit and sit properly within the larger "V" represented by the groove). I also believe I have read that, generally speaking, and assuming a cartridge properly mounted in the headshell, a tonearm that inclines toward the cartridge tends to accentuate high frequencies, while an arm that is down at the pivot end tends to accentuate bass (these arm angles, respectively, causing the stylus to lean forward or to recline in the groove as compared to sitting perfectly upright), and that, level to the platter is generally considered the best starting point. I know that actual VTA varies with every LP depending upon disc thickness and several other parameters.

Are there any owners of VPI arms with v.d.H cartridges out there, or people generally savvy to turntables, who have experimented at length with set-up parameters that have advice to share? Any general or specific advice would be welcome. I am reluctant to undo the expert work of the installer who installed the cartridge (for example, I would definitely not try to change azimuth), but wonder whether any of you have found that doing any particular things were really good (or really bad).

I am passing the content of this query to George Stanwick and to Sheila Weisfeld whom, I admit, I have never previously asked about this subject (mostly due to the alleged sensitivity of v.d.H cartridges to set-up, I have deferred to the installer's set-up since the cartridge was installed).

Many thanks in advance for responses.