Stylus force digital scales

lewm09-26-2017 3:00pm

Cleeds,
Imagine that you are the stylus tip.  With the arm wand parallel to the LP surface, someone has set VTF for 1.5gm.  Now imagine that you encounter a record warp ...

I understand record warps and the dynamic nature of VTF. That's exactly why I mentioned the differences between statically balanced and dynamically balanced pickup arms.

Imagine that the tonearm has unlimited travel in the vertical plane.  It could then point straight up at the ceiling. What would be the VTF in that case? Zero.

That's absurd, because a pickup arm would never be vertical. The truth is that static VTF - within any normal range of a pickup arm - is not influenced by the thickness of a record.

Do you weigh more when you lie down or stand up?

You don't understand.  And you don't want to understand.  So why bother?  Read a physics book with a chapter on Newtonian Mechanics.

Or simply do the experiment I suggested: Measure or set VTF with the tonearm parallel to the surface of an LP.  Then place a couple of spacers under your digital scale so that the cartridge has to be raised by a cm or two in order to sit on the weigh pan, and the tonearm is now tilted "up" with respect to the pivot, and measure VTF again.  The difference will be very small, but there will be a difference.  (Which is why I suggest using a digital scale; you'd never detect it with a Shure stylus gauge.)  Don't come back at me until you've done this.  If your tonearm bearings are excessively high in friction, it could obscure or enhance the results.  

You don't seem to get that the thought experiment is valid; if the tonearm is completely vertical, VTF is zero, which means that as the stylus traverses the vertical arc of the tonearm between horizontal and vertical, VTF is gradually decreasing.  

By the way, I never said that the thickness of an LP would make a big difference.  The question was does it make ANY difference.  It makes a small difference. Warps can transiently make a bigger difference.

Folfreak, The digital scale that jbny referenced has a non-magnetic weigh pan.  Or at least it says so on the spec sheet to the right of the photo. Thus it should not be influenced by the magnet inside any cartridge, even the stronger magnets in MC cartridges.  That same scale recommended by jbny has evidently been re-packaged to death, in both metal and plastic cases.  I see it all over the place under different brand names, and in fact I own one with a metal case, for which I paid about $50.  I check mine regularly with the reference weights, and it remains very accurate.

lewm

You don’t understand. And you don’t want to understand. So why bother? ... Or simply do the experiment I suggested: Measure or set VTF with the tonearm parallel to the surface of an LP. Then place a couple of spacers under your digital scale ... measure VTF again ... Don’t come back at me until you’ve done this ...

Pardon me, but I’m not obligated to complete your homework assignment as a prerequisite to posting here. I’m sorry if that troubles you.

You seem to enjoy engaging in hair-splitting "thought experiments." You’ll have to accept that such exercises as imagining that I’m a phono stylus don’t interest me.

Two things you either don’t understand, or don’t want to understand:

1. The thickness of an LP has a trivial effect on VTF. Unless you’re playing discs that are an inch thick, the variation in static VTF between the thinnest Dynagroove LP and the thickest MoFi (or whatever) remaster is trivial. And yes, I’ve confirmed this with an accurate digital scale.

2.) Dynamic VTF - which is influenced by such factors as record warp - is nowhere near the absurd plus-or-minus 50 percent range you’ve claimed, provided that the pickup arm and phono cartridge are properly matched and calibrated. In addition, the use of a dynamically balanced pickup arm will greatly reduced the degree of VTF deviation and, as I’ve previously explained, this can easily be confirmed by observing the phono cartridge’s cantilever deflection as it navigates a warp.

Further, to be clear, the actual sonic benefit of using dynamic balance in a pickup arm is hotly debated, with many arguing that a statically balanced arm delivers better performance. Without taking a side on the debate, it’s clear that the enduring debate itself suggests that the consequences of a cartridge’s varying VTF as it navigates an LP is nowhere near as critical as you would seem to suggest - again, provided the system has been properly matched and calibrated from the outset.

Some users of dynamically balanced pickup arms such as the SME V apply VTF by using equal amounts of static and dynamic force. You might want to try it sometime, if that’s an option for you.