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Who tweaks VTF too?

I can't say why it took many years for me to suddenly arrive at this point -- although I can identify the precipitating occurance as actually being mistake I made (as I suppose is often the case with many discoveries, large and small) -- but I've recently opened my ears to the practice of tweaking VTF for each record played, to very worthwhile effect. Generally within a range of up to about +.15 above the upper limit of the cartridge manufacturer's recommended setting of 1.35g-1.5g for my medium-compliance, line-contact MC cart -- i.e., up to 1.65g or anywhere in between, depending on the record being played, in about .025g increments.

Tracking a bit heavier accentuates the lower frequencies and tames the higher ones, for records that could use more weight or solidity and/or a reduction in gleam or glare or airy-fairyness, while tracking lighter does the opposite for records that sound overly thick or could use some opening-up (within the bounds of maintaining good groovewall contact, of course -- I never even run in the bottom half of the recommended range, much less below it). This minor revelation has helped significantly to increase my listening satisfaction with records I formerly would've just chalked-up as being slightly but irretrievably problematic, whether that problem might have been a subtly annoying touch of glassiness or peakiness or lightness in the loafers.

Each recording seems to have its own sweet spot balancing control, tonality, timbre and texture (within my system context), and after doing this individual fine-tuning procedure for a few weeks I've now started to intuit appropriate setting adjustments as needed, based on a record's initial sound and my growing experience with the outcomes. So I've definitely crossed over the proverbial Rubicon regarding tracking force and no longer regard the recommended range as inviolable, or VTF generally as a set-and-forget, one-size-fits-all proposition whose 'correct' value is predetermined, to be temporarily increased only in the event that dynamic-trackability difficulties are encountered. It's another thing to be tweaked! But also one of the easiest and quickest to do (at least with my tonearm -- I guess with some others maybe not so much). Anybody out there with me on this?
zaikesman
onetwothreego
54 posts
 
I didn't say I run my cart in the lower region of VTF. More often than not, when the arm is performing up to spec, the sweet spot is pretty much in the middle of the suggested range, as one might expect.

With all the carts and arms I have used over the years, increasing the VTF to the upper range squashes the music, as far as my ears hear it. Bass loses its bounce and become a thud. The highs become almost forced down into themselves instead of breaking away free. All the musicians lose their timing finesse.

The biggest factor in the equation of all this VTF stuff is not the cart but rather the arm and how well it is doing it's job.
zaikesman OP
3,017 posts
 
Possibly. In any case, whether the preferred VTF region happens to fall in middle of the recommended range, or above, my point is that it may be considered as a range, rather than a specific value, with room to tweak as desired. Clearly however I remain in a minority of one with this view.
rockitman's avatar
rockitman
417 posts
 
By adjusting VTA on the fly for each record I play, I am in effect also changing the VTF
zaikesman OP
3,017 posts
 
Again, largely disagree with this contention. Maybe I will try measuring any such change with my digital VTF meter, since some of you are positing not only that it exists but that it is significant. (Maybe some of you will do the same?) However right now I'm guessing that the small angular change effected by adjusting VTA even by several millimeters could only result in the most miniscule of VTF differences, perhaps on the order of one or two hundredths of a gram at most (the limit of most guages' resolution in any event).

But even if changing the tonearm height did more substantially affect the VTF, should you always necessarily want to change the VTA and the VTF in lockstep? Again I would submit that the fact that increasing VTF also has the side-effect of decreasing SRA (or vice versa) must be of more significance than whatever effect changing VTA has on VTF, but probably still not as sonically significant as the effect on the suspension loading and groovewall contact that a heavier (or lighter) tracking force has in and of itself.
jcarr
341 posts
 
Ideally the bearing of the tonearm should be at the same height as the LP surface, otherwise there will be changes to VTF as the cartridge goes up or down with record warps. The greater the vertical distance between tonearm pivot and LP surface, the greater the magnitude of the VTF modulation. The same thing is true for the tonearm's center of gravity, which, if changes to VTF as a function of height are to be minimized, should properly be at the same height as the LP surface.

VTF modulations as a function of cartridge playing height will then cause the angle of the signal coils to change within the field of the magnetic gap, and the SRA to change. Both can be a source of non-linearities or IMD.

Whether the changes in SRA will be audible or not are partly down to the stylus profile - usually a long-footprint line-contact stylus with a narrow side radius will be most sensitive, while a conical may not be sensitive at all.

The change in coil angle with VTF may or may not be so clearly audible - it depends on the cartridge. The reason is that with most cartridges, there are two different VTF "sweet spots", one higher, the other lower in value. The lower value VTF sweet spot will align the signal coils so that they are parallel to the magnetic gap, which gives best linearity (which may or may not be the same thing as maximum output), and the most equal values for horizontal and vertical compliance. However, the lower value VTF will usually not be sufficient for optimal tracking of the LP groove.

The higher value VTF sweet spot will allow optimal tracking of the LP groove, but will push the coils out of alignment with the magnetic gap.

This is why you typically see a quite large recommended range for VTF from the cartridge manufacturer - the wide range signifies that a compromise between two different requirements is occurring.

OTOH, a cartridge that has been designed so that the VTF value which aligns the signal coils to the magnetic gap coincides with the value required for optimal tracking, will have a quite narrow recommended VTF range from the manufacturer.

hth, jonathan carr
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