I'm scratching my records


After carefully setting the stylus pressure using a scale (to the lower end of the Lyra Helikon's recommended setting) on my JMW 12.5, the needle will 'skate' when initially placed on the lead-in groove until it 'hits' the music tracks and makes a horrible and damaging sound...(Now my Norah Jones LP has a minutes worth of 'tic-tic-tic-tic' :(

Is my stylus pressure too low, or too high?

Not all records do this, maybe 30%, and if I'm careful to get the stylus very near the music start and away from the edge as much as possible it helps.

Suggestions, comments, criticism??? All appreciated.

Damn, this analog is hard!

John
Atlanta, GA
jbatlanta
John,

The last individual had it right: the problem is your antiskating force. Since the VPI tonearm doesn't have this feature, you must twist the tonearm wires in the direction opposite to the skating direction, clockwise if you're facing the front of the 'table, and then connect them. If one twist isn't enough, then try two. Also, don't be afraid to increase the stylus force pressure, as too little does more to damage records than too much. Do this before you twist the wires, as the skating force is tied to the pressure. Head toward the upper end of the recommended range.
I agree with SDcampbell that insufficient anti-skating force could contribute to this problem, but I disagree with the suggested method of setting it.

Skating force is a function of friction and offset angle: the record groove moving past the stylus pulls upon it at an angle to the stylus-pivot line, causing the arm to swing inward. If the stylus is not riding in a groove, the friction acting upon it will be much lower, so the resultant skating force will be proportionately reduced. Skating force even varies with the dynamics of groove modulations, because larger modulations result in more friction. Adjusting one's anti-skating to compensate for the much lower force of a flat surface is unlikely to correlate well with the actual skating force that occurs when the stylus is in a modulating groove.

I'm also not sure it's a good idea for the stylus to be run while resting on its point. Maybe harmless, but it wasn't designed to do that and clearly the tip must be the most vulnerable part.
You might also check to make sure you are starting with a LEVEL table. No insult intended; just good to check the basics since what you are experiencing is consistent with a turntable on a slight tilt.
DD is right - you're tacking force is probably set too low, but SDC is also right, because correct anti-skating force is determined by tracking force (more = more), and with a VPI 'arm, chances are you're employing very little to no anti-skating force at present if you haven't made the 'wire-twist' adjustment (or the dealer hasn't). I would second the recommendation for a tracking force in the top half of the specified range - or even just go straight to the very top when in doubt, and then you can experiment with auditioning slightly lighter VTF's, if desired, after your problem has been identified and rectified. I would stay away from trying to track at the bottom of your cart's listed VTF range - in most cases it will sound worse, and can cause far more record (and needle) wear if it's too light than if it's 'too' heavy (the recommended range will never really be 'too' heavy, as you can observe by looking at the degree of deflection exhibited by your cantilever's suspension when the tonearm is lowered - there will still be plenty of vertical travel available even at the max recommended setting).

DD is also right about the shape of the lead-in groove 'shoulder' on some LP's being more treacherous than others, but I wouldn't worry about the impact of groove modulation on skating forces. In fact, the way tracking force is set correctly using a special test record is for the stylus to be lowered during platter rotation, in the middle of the 'arms radial travel (the central area of the record's playing surface, about halfway between the lead-in and run-out grooves), on a smooth, *ungrooved* 'track' included for just this purpose, and the anti-skate is then set so that the needle tracks this grooveless area straight, without wandering toward the record's label or edge (this must be done after the tracking force has been set). Since VPI 'arms do not have a calibrated anti-skate control, I would suggest you should pick up such a test record.

Other than that, I also think it is a good idea to become comfortable and competent with cueing by hand, if you're used to depending on the cueing lever. It's tough to precisely line up the needle over the desired groove area with the 'arm being held aloft via the lever control, but you can also get a 'feel' when cueing by hand - unavailable via the lever - for whether or not you're in the 'sweet spot' of the Track #1 lead-in area just prior to releasing the tonearm, and you can reposition and make adjustments before letting go if it feels wrong. With the lever, you have to actually see the problem occur first, and then there's always a slight delay in the lifting action once you've decided to abort that can prove fatal. It takes a little practice, but once you've gotten adept at hand-cueing, you'll never go back to using the lever except maybe when the phone/doorbell rings during listening.
Nice post Zaikesman, excellent advice. Considerable physical involvement is necessary to play LP's properly anyway. Why not cue manually?

I'd forgotten that a JMW lacks any real antiskate mechanism. If his wires aren't twisted (or worse, if they're twisted the wrong direction) the lateral acceleration on that downslope will be even faster.

Happy New Year to all!