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What angle should I set the VTA on my VPI turntable?

I can't believe after all these years, I am asking such a basic "analogue 101" question, but here it goes. I own a VPI turntable that has a "VTA on the fly" knob.  I thought the best VTA setting was for the arm to be 100% parallel to the record surface.  

However, based on some research, I am not so sure that is correct way to set the arm to achieve optimal VTA and correlatively, optimal SRA.  Not sure, ... but I think I have to raise the pivot side of the arm.

Any advice would be appreciated. 

Thanks.     
bifwynne

Showing 4 responses by cleeds

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cleeds
5,694 posts
 
wlutke
When VTA is changed, adjusting the tail up decreases VTF.
Just the opposite: Raising the "tail" (pivot) will increase VTA.
See VTA/SRA diagram here.
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cleeds
5,694 posts
 
wlutke
cleeds,
Wrong. On a unipivot the balance changes and I am correct. You’re comparing VTF and VTA. Two different parameters.
You’re obviously confused.
VTA = Vertical Tracking Angle. Shown here.
VTF= Vertical Tracking Force. That’s the weight (force) on the stylus as it sits on the LP surface.

If you raise the "tail" (pivot) you can only increase VTA. It’s simple geometry - again, see diagram.

I’m not sure why you mentioned VTF but since you did: Increasing VTA by raising the "tail" (pivot) will also increase VTF. It will also decrease overhang. Again, this is all basic geometry and physics.
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cleeds
5,694 posts
 
lewm
... The question then was not "whether" VTF goes up when the pivot point is raised, but "how much" does it go up. Someone did the experiment, and the answer was "not very much", but definitely VTF went UP.
Yes, it goes up, and it's easily measured with a stylus force gauge.
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cleeds
5,694 posts
 
lewm
... you and a friend are carrying a sofa. On level ground, the burden is equally shared. Now you have to carry the sofa up a staircase. Who is working harder? The guy at the top end or the guy at the bottom end? Raising the pivot point shifts the center of gravity toward the stylus. VTF goes up.
Correct. This is basic physics. It’s odd that anyone here would need the explanation, but @wlutke clearly needs some help.
wlutke
I’ve done the work, taken the measurements. Nuh-uh is not a rebuttal. Show me
We’ve explained the geometry and the physics to you. Now it’s up to you to understand.
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