tonearm questions

I have had problems with the stylus skating in from the lean in spiral, even though, I seem to have all my adjustments properly set up...

Dave,
This is normal for any properly set up arm with high quality bearings, which your IV certainly has. Four factors combine to cause this behavior:

1. the stylus is more likely to touch down onto bare vinyl than hit the groove, so there are no sidewalls to resist lateral movement;

2. the instant the stylus contacts spinning vinyl, skating forces try to pull the arm inward

3. most LP's have an inward sloping lead-in ramp, so gravity is reinforcing the inward tendency;

4. high quality bearings present little resistance to arm movement (arms with rough, tight or sticky bearings have enough friction to mask this situation, which is why people moving to a top level arm from cheaper ones are often surprised or think they've misadjusted something).

There is no adjustment you can reasonably make to counteract this. Increasing antiskate to very high levels would prevent it, but that would be far too much antiskate for proper performance once the stylus finds the groove.

The "cure" is to cue slowly, carefully and purposefully. Don't just flip the cueing lever and walk away. Maintain control of the arm during cueing and listen for the stylus to find the groove. Once it does it's safe to release or push the cueing lever all the way down. This is especially tricky on edge-warped records BTW. Practice on flat ones first.

Doug

Also, call me stupid, but I always figured that anti skating worked in the opposite direction. It seemed, that if I were a stylus, riding in a groove, centrifugal force would tend to spin me towards the outer edge of the record, so I figured anti-skating would counteract this, by exerting some inward counterbalancing force. What you're saying is that the opposite is true. Yes?

Since you're smart and brave enough to ask questions you aren't stupid. Ignorance is okay. We're all born with that! ;-)

Skating has nothing to do with centrifugal force. In fact, with a properly aligned cartridge there is no centrifugal force. If the stylus is properly tangent to the groove then friction from the groove acts directly along the line of the cantilever. In an ideal setup there is no outward (or inward) force (on the cantilever).

Skating force exists only on pivoting tonearms with offset (angled) headshells. Groove/stylus friction pulls directly along the line of the cantilever, but since the cantilever isn't pointed directly at the tonearm pivot a force vector is created. This force pulls the arm inwards and we call it "skating". Anti-skating devices are intended to counteract this inward force by pulling the arm outward, hopefully with an equal amount of pressure.

Doug

P.S. I doubt I ever recommended the SME IV damping option. I don't own an SME and I've used the V but never the IV. OTOH, if you like it it was *definitely* my idea!