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

Showing 3 responses by dougdeacon

John,

You've actually asked two questions, one about cueing a record, the other about Vertical Tracking Force. A perfect VTF setting will not prevent what happened to Norah. :( The ideal setup is optimized to let your stylus accurately trace a groove it's already in. Decelerating a stylus on a sideways-sloping glaze of ungrooved vinyl would require a very different, and horrible sounding, setup. Let's address these two questions seperately.

SETTING VTF
I don't know the JMW or Helikon, but most top cartridges work best in the upper half of their recommended range. It is a popular misconception that lighter VTF is good for your records. Precisely the opposite is true. It's hard to think of anything worse for a plastic groove than sending a diamond spike bouncing back and forth between the walls due to inadequate controlling pressure. Optimal VTF will control the stylus just enough to let it trace both groove walls accurately without over-damping.

The way to set VTF is by listening to music with a lot of dynamic, HF content. If VTF is too low, HF's will sound shrill or broken up. If VTF is too high, HF's start to disappear altogether.

CUEING RECORDS
The problem is the stupid record manufacturers, who invented raised edges to seperate records from each other in a stack on a changer. Anyone who stacks records on a changer should get the scratches they deserve. Why make the rest of us suffer? (Many 200g audiophile pressings have a nice flat lead-in area and lots of lead-in grooves, not just one or two.)

That little downslope is a terrible risk. ALWAYS look for that. If the record has one then you've already discovered the solution. Place the stylus as near to the bottom of that slope as possible, erring toward the music side if necessary. Better to miss the first few bars than destroy them forever. If the record seems dodgy for cueing accurately I'll control the stylus drop speed myself, not just trust the damping. This is especially important if the record is warped.

Damn, this analog is fun!
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.
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!