Hi Jonathan, thanks for injecting some authoritative input into the meanderings on this thread. What you say all makes sense to me, however I would still expect some session-to-session variation in optimal (or preferred) geometry to be probable with any cartridge, based on differences in prevailing environmental conditions affecting the suspension, as well as differences among the way records are cut (or from my perspective and ability to tell, simply in the way they sound). Do you disagree with my take that in all likelihood, there's no reason one should go really wrong as a listener by using the best tool we have available, namely our ears, to tweak these parameters, including VTF within reasonable limits, on a record-by-record basis?
BTW, I do realize (even though you chose for whatever reason not to say so as a disclaimer) that you are involved in the design and marketing of a cartridge line that is claimed to take into account the effect of tracking force on optimal coil alignment within the magnetic gap. This would of course seem to make obviously good sense -- in fact, so much so, that I actually have a bit of a hard time believing either that other manufacturers have never taken this factor into account themselves (whether they said so or not), or else that they didn't determine that it's in reality a relatively unimportant consideration as regards sonic performance. (One can't help but note that by implication, your cartridges too did not previously take this factor into account, or else that you knew about it but considered it to be fairly trivial.) Still, even if it's as much marketing as science, the concept does strike me as being a really good idea for a cartridge maker to tout, so bravo. Please feel free to comment!
FWIW: Yesterday I went ahead and made a bunch of VTF measurements using my digital gauge (the kind commonly selling for $80 from many outlets), for both the lowest and highest VTA adjustment settings possible with my tonearm, which amounts about an 8mm differential in height of the pivot point -- quite a bit broader an angular range than anybody would actually utilize for setup or tweaking of any individual cartridge.
First I confirmed the precision of the gauge (to within whatever limits are imposed by the quality of my tonearm bearings) by making many measurements without changing anything. As I have found before, despite the fact that these gauges have a readout to three decimal places, it's only to the second decimal place that readings are close to repeatable, to within an accuracy of about plus or minus two (i.e., a margin of error of about 4 hundreths).
I was pleasantly surprised but hardly shocked to find that, as I predicted, the variation in VTF (from a baseline setting of 1.5g) which accompanied the widest possible change in VTA, only amounted (on average, over about 30 or so repetitions of the readings for each VTA extreme) to approximately .02g (i.e., about plus or minus one hundredth from the force reading that could be expected at the middle of the arm's VTA range), which is of course within the gauge's margin of error. Despite there being some overlap in the force readings at each arm-height extreme, I do think this small average force differential is nonetheless real, due to the overall trends I observed over the course of the measurements, but that it is probably too small to account for any sonic differences, especially given that in practical use the actual VTA range will be quite a bit less than what I was experimenting with.
So my conclusion is that it's unlikely that adjusting VTA represents, consequentially speaking, a secondary adjustment of VTF as well. But I would welcome what any other posters' findings might be on this issue, if anyone cares to make the kind of measurements I did, perhaps using better tools and a more premium tonearm. Still, at the end of the day I didn't start this thread to get into such technical considerations -- I started it because of what I heard, and to see if anyone else had also heard and was doing the same thing in tweaking VTF to suit their listening of the moment. Continues to seem like not so much...
PS - All the adjusting and measuring I performed yesterday, along with subsequent listening, did have the beneficial effect of prompting to me to slightly raise my tonearm's baseline VTA setting in order to increase the SRA a bit, so as to offset the effect on the rake-angle of the somewhat heavier (on average) VTF I'm commonly running these days. My thanks to those posters who pushed me not to forget such interrelated considerations!
BTW, I do realize (even though you chose for whatever reason not to say so as a disclaimer) that you are involved in the design and marketing of a cartridge line that is claimed to take into account the effect of tracking force on optimal coil alignment within the magnetic gap. This would of course seem to make obviously good sense -- in fact, so much so, that I actually have a bit of a hard time believing either that other manufacturers have never taken this factor into account themselves (whether they said so or not), or else that they didn't determine that it's in reality a relatively unimportant consideration as regards sonic performance. (One can't help but note that by implication, your cartridges too did not previously take this factor into account, or else that you knew about it but considered it to be fairly trivial.) Still, even if it's as much marketing as science, the concept does strike me as being a really good idea for a cartridge maker to tout, so bravo. Please feel free to comment!
FWIW: Yesterday I went ahead and made a bunch of VTF measurements using my digital gauge (the kind commonly selling for $80 from many outlets), for both the lowest and highest VTA adjustment settings possible with my tonearm, which amounts about an 8mm differential in height of the pivot point -- quite a bit broader an angular range than anybody would actually utilize for setup or tweaking of any individual cartridge.
First I confirmed the precision of the gauge (to within whatever limits are imposed by the quality of my tonearm bearings) by making many measurements without changing anything. As I have found before, despite the fact that these gauges have a readout to three decimal places, it's only to the second decimal place that readings are close to repeatable, to within an accuracy of about plus or minus two (i.e., a margin of error of about 4 hundreths).
I was pleasantly surprised but hardly shocked to find that, as I predicted, the variation in VTF (from a baseline setting of 1.5g) which accompanied the widest possible change in VTA, only amounted (on average, over about 30 or so repetitions of the readings for each VTA extreme) to approximately .02g (i.e., about plus or minus one hundredth from the force reading that could be expected at the middle of the arm's VTA range), which is of course within the gauge's margin of error. Despite there being some overlap in the force readings at each arm-height extreme, I do think this small average force differential is nonetheless real, due to the overall trends I observed over the course of the measurements, but that it is probably too small to account for any sonic differences, especially given that in practical use the actual VTA range will be quite a bit less than what I was experimenting with.
So my conclusion is that it's unlikely that adjusting VTA represents, consequentially speaking, a secondary adjustment of VTF as well. But I would welcome what any other posters' findings might be on this issue, if anyone cares to make the kind of measurements I did, perhaps using better tools and a more premium tonearm. Still, at the end of the day I didn't start this thread to get into such technical considerations -- I started it because of what I heard, and to see if anyone else had also heard and was doing the same thing in tweaking VTF to suit their listening of the moment. Continues to seem like not so much...
PS - All the adjusting and measuring I performed yesterday, along with subsequent listening, did have the beneficial effect of prompting to me to slightly raise my tonearm's baseline VTA setting in order to increase the SRA a bit, so as to offset the effect on the rake-angle of the somewhat heavier (on average) VTF I'm commonly running these days. My thanks to those posters who pushed me not to forget such interrelated considerations!