VTF Experiment Help Please

VTF Experiment Help Please

Postby Dizastical » Fri Nov 23, 2018 4:21 pm

Today I received my new digital force gauge. While I was recalibration my VTF I had a thought. The measuring plate of the scale is way higher than the thickness of a record. I though to myself that the difference in height has to effect the actual VTF on the record surface. To try and figure out just how much the difference in VTF is I decided to try a little experiment. First I measured the thickness of 25 records of various weights to get an average of thickness. I know it’s not an exact figure but I wanted a base height for this experiment. I came up with an average of 1.5mm in record height. I then measured the height of the scale plate. It is 6mm high. So the difference between the two is 4.5mm. To see what kind of change the VTF has between these two heights I first set the VTF to 1.6 grams on the scale. I wanted to simulate the height difference of the scale and record surface so I raised the VTA tower 4.5mm (5 full rotations) and checked the VTF on the scale. It came in at 1.4 grams. I knew that there would be a difference but i had no idea it would be that big of a difference in force. My question is...... is it safe to assume that in order to get the proper VTF at the record surface, I need to add .2 grams to the VTF on the scale to compensate for .2 gram loss due to the the height difference of the scale and playing surface? I’m just making sure that my findings are correct. Any help with this would be great.
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Re: VTF Experiment Help Please

Postby JimmyL » Sat Nov 24, 2018 1:20 pm

Interesting observation.
I would think you’re on to something but I guess it would depend on how the recommended VTF was established. IE, what type/height of measuring device was used by the cart manufacturer.

I guess it would come down to your own ear and tracking performance. The .2 variation isn’t hard to to a comparison.
Let us know what you decide upon? Might be worthwhile to play with...
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Re: VTF Experiment Help Please

Postby Golear » Sat Nov 24, 2018 4:54 pm

It's hard to make a generalization because various VTF scales will have different heights, and LPs also have different thickness, and the grooves are cut at different depths.

I suggest:
1. Place the scale on the platter, then put the arm on the scale.
2. Raise/lower the VTA until the top of the cartridge is parallel to the platter. This can, of course, be hard to do. You might need to buy a VTA gauge or make one.
3. Set the VTF. I set to the max. recommended amount.
4. Remove the scale.
5. Put an LP on the turntable and put the arm on the LP.
6. Repeat step 2.
7. Listen to the LP then make fine changes to the VTF by ear. When the VTF was too high, the bass was "smushed down". At the right VTF, the sound opened up, and the bass response went lower. I have a Soundsmith Counter Intuitive, so it's very easy to make fine VTF adjustments.

By doing (2) and (6), you don't have to worry about the height of the stylus gauge, the thickness of LP or the depth that the grooves were cut.
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Re: VTF Experiment Help Please

Postby patagonia » Sat Nov 24, 2018 5:56 pm

I made a plattform made from cardboard to put the scale on, next to the platter with the correct height, problem solved.
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