tonearm questions

Nsgarch,

I've got an SME series lV arm (on an Oracle MK V table) that I just purchased a fluid damper for. I don't really know how old the arm is? How should I go about determining if I should send it back to SME for service and new wiring? Any suggestions are appreciated.

Thanks
Rolloff

Rolloff, the internal wiring of the SME IV is a metallized ribbon, not wire. Supposedly, this presents less resistance to the bearings, and is also supposedly more compatible with MC cartridges -- for which this arm was specifically designed. So you wouldn't want to change it IMO.

The arm itself is not that old , maybe 5-8 years? You can find out but it is much newer than an SME V, and unless "you don't know where it's been" it shouldn't need routine service.

As for the damping tray, I can't tell you if you really need it or not because I can't find any info on the compliance of the Shelter 90X. (You probably don't.) Most MC cartridges have low(ish) compliance and are appropriately used in med to high mass arms (like the SME IV.) So the arm doesn't need to be damped as far as resonances are concerned, though it can help to keep the arm from overshooting the lead-out spiral, but that shouldn't happen if the table is level and the arm limit properly set.

Now if you were to use a high compliance cartridge (like a van den Hul, or many of the MM or MI cartridges) in a med/high mass arm, you might find the damping helps.

Here is a quick overview of the issue:

http://www.gcaudio.com/resources/howtos/tonearmcartridge.html
.

Nsgarch,,
As always, thank you for sharing your valuable knowledge. I got the damper, mainly as it give me the ability to more easily adjust the VTA. I'll look at the article you posted. Interestingly, I use a Thorens Q up for lifting the arm at the end of the lead out spiral, and have never noticed a problem there. 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...

Thanks,
Dave

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

Good info here from Neal and Doug. I have found that some of my lp's just defy cuing without falling into the groove with a bit of a jolt.

Just me or do you guys have a few of these records as well?