VPI Tone Arm Wobble when lowering and cueing the tonearm.

@avanti1960, the wobble decays over time, whether the arm is in space or playing a record. It may wobble for the first few seconds an LP side but goes away.

Foot falls, or in my case, a passing train, can get the arm to wobble again but the resonance will once more decay.

In any event, in general it's not audible. I've tried to hear effects of a normal wobble but I can't. Extreme wobbles, yes, but you should see the effects on me when I'm walking with an extreme wobble.

 

If your arm is wobbling from foot-fall or anything externally, you need to isolate it better. A LOT better.

 

@Cliff, I solved the foot fall issue in my house by simply putting a couple of wood blocks between the stereo stand and a built-in bookcase behind it. That bracing solved the problem. Back in my stereo store days, when a customer would come in complaining of foot falls making their records skip, I told them to shove an old coffee cup between the cabinet and the wall.

 

mine does NOT wobble while in play, just while queing

 

Mine never wobbles during playback, just during while lowering the arm. I have a few slightly warped lp's and it doesn't wobble on these either. Footfalls are no issue if you have the table isolated properly. I have mine on top of a 3" solid wooden slab which is isolated from my equipment rack using roller blocks. My granddaughter (10 yrs old) loves to dance and jump around in my audio room when I have certain music on and I have yet to experience any ill effects from all of her movement. Once you get used to cueing with a unipivot arm, the concern is non-existent.

 

I have a Moerch unipivot and it does not wobble at all when damped with correct oil. It behaves as any tonearm. Cueing by hand is the easiest, it does not wobble.

 

My bad, it wobbled both when cuing and in the groove, sorry for the confusion.

 

Pray tell me how you use the laser level device to check azimuth and which one do you use?

JG

 

I have a Classic 2. I don't experience any cueing wobble. I used to get wobble from footfalls until I moved the table to a wall mount shelf.

 

OK those are two separate problems. The more serious one is wobbling in the groove and that is almost always resonance or warpage. Unless your tonearm is not secure for some reason.

Wobbling when cueing I thought was rather a known issue and could be resolved with tweaks.

 

Something's not right with your analysis here - 2HZ resonances while actually playing records would be disastrous, as any large warp would be simply unplayable. The cartridge suspension/tonearm+ cartridge mass resonance isn't at 2Hz either - that's separate to the free resonance of the system when not playing records. It's not as basic as you make out, my friend.
One other bonus of a unipivot may be related to warp tracking - a pinch warp in particular. This is a part of the record that needs a unipivot to track the groove whilst remaining perpendicular to the groove. Gimbals and knife edge bearings don't allow cartridges to roll around their longitudinal axis.

 

John, I am a stereo salesman by trade. We like to tell simple stories. I may be full of horse pitute. It wouldn't be the first time I was on this forum but here is my methodology for saying the resonance of the arm is 2Hz. I've done this experiment before and I just did it again.

1. I place the tonearm down on the record roughly, trying to get as much wobble as I can.
2. Once I can get a good focus on the finger lift, I start a stopwatch when the lift wiggles over to the right. Think of this point as "far wobble right."
3. I count ten of these wobbles and on the tenth time the finger lift moves to the right, its tenth cycle, I stop the stopwatch.

I was able to get four measurements when I thought I did this correctly. It is harder than it seems to start the stopwatch at the exact same moment I see the finger lift move to the right. There were at least ten "do it again" failures for everyone that was successful. The time for ten wobbles were 4.17, 4.13, 4.18 and 4.48 seconds. Throwing out the 4.48 as it seems to be an outlier and adding the other three together, I have 12.48 seconds. Dividing that by 30, the total number of wobbles I observed, I end up with each wobble taking .416 seconds, or with there being 2.4 wobbles per second. The tonearm is wobbling at 2.4 cycles per second. That would be a resonance of 2.4Hz, at least as I understand it.

2.4Hz is higher than I measured in the past. I thought I'd measured it before with the 3D arm but maybe I didn't. Maybe my 2Hz figure was using the aluminum arm. In any case, both numbers are in the same ballpark.

I got this methodology from @missan, when I used it to figure out the resonance of my suspension using the Swedish Discs of Silence feet. That came out to be 4Hz. Here's that thread.

We could have a further discussion on your concerns but that will have to wait until tomorrow. I have to leave in a few minutes to do sound for a string band tonight at a wonderful little club in my area, Leo & Leona's in Newberg Corners, Wisconsin. Come by and say hello.

 

That resonance musn't be an issue whilst playing discs, for what ever reason, I suppose.

 

If my Prime wobbles it is my fault. But your instructions do say (at least mine do) that if it does, it should not effect sq, so as Steve said, might not be anything to really worry about. I have a question for VPI owners though: it's really difficult for me to cue up. When the lever goes down, the arm goes back an inch or more. I'm wondering if it's cart dependent? I just upgraded from a MLX150 to an ART9 and its' much, much better though it sometimes still strays a bit. Didn't experience this at all on any other table I've ever owned. Not a third world problem, just curious. I wouldn't worry about your wobble issue.

 

The arm shouldn't move like that when cueing. Something is off. Too much antiskate or there is too much tension on the tonearm wiring.

 

My guess would be too much antiskate.

 

Anyone how owns a VPI Unipivot should remove the arm, check the Pivot Point, it should be near needle sharp. Also check the 'cup" on the inside of the Tonearm Bell, it should not have ANY burrs or imperfections at all.

A sharp Pivot and a clean cup, and the Arm will be very smooth, at least mine is. Zero wobble on cueing or in the groove. Just an observation.

 

Yup!
M~

 

I'll take a close look...thanks guys for the suggestion.

 

I am a bit concerned about unipivots that wobble like that - how would they react to disturbances in the record and how can azimuth be stable? When I put my Moerch UP-4 with correct damping fluid on the record according to 1, the tonearm just adjusts to the center and is steady. No wobble, and it is not possible to measure any resonance.

 

^ @Thomas_A , I understand. All I can say is I can't hear your concerns. The wobble quickly fades. The VPI arm is stable, just in its own way. But that doesn't say that it's the best way to do a unipivot arm, only that it's a successful one. I'd love to play around with yours.

BTW, you can use damping fluid with the VPI arm. Most people don't.

When you posted, I was writing the following note. I can't figure out how the VPI arm works, either.

Agreed, completely, especially when it comes to implementation of those basic engineering principles. The JMW Memorial Arm is a marvel. For years I was intellectually against it. Of course I hadn't used or even listened to it for any period of time at that point, but, hey, I'm an audiophile. I don't have to have actual experience with a product before having an opinion. The arm simply didn't make sense to me.

How could the tonearm even work? When playing a record, its entire mass is resting on two points, the pivot and the stylus. One of those points is moving rapidly, reading tiny wiggles in plastic coming from two different directions, 90° from each other. With part of the mass of the arm resting upon it, the stylus has to trace those passing waves of plastic perfectly. Just step back and look at what we have here. Picture the tonearm sitting on two needles, with the perfect motion by one of them essential for the tonearm to work right. Just think about that. Harry Weisfeld is an amazing engineer.

 

James, The device I use is a Bosch GLL2-10. Unfortunately, they do not make this model anymore, however, I think the GLL2-50 ( GLL 2-50 | Self-Leveling Cross Line Laser Level | Bosch Power Tools ) is pretty much the same. It is essential that you have a good tripod that you can mount the device on. The tripod I use is from my wife's adventures in photography some 40+ years ago so I cannot recommend a tripod since I doubt that the one I use is still made. I start by making sure that the platter is level by adjusting the leveling devices on the TT until the red line from the laser just touches the top of the platter. Then I put the small rod that comes with the VPI TT on the head shell and adjust the azimuth setting until the laser line paints the entire length of the rod red. It this point I am satisfied that both the platter and the azimuth are level within less one degree.

 

I have noticed that there is some discussion of the effect of anti-skating on tonearm wobble. Just like HW, I do not use any anti-skating device on my JMW tonearms, I have completely remove the supplied anti-skating device from the tonearm.

 

Great information, thanks for that! I definitely have a small tripod that I bought years ago. Now where the hell did I leave it?

JG

 

Keep in mind that the head shell being level may be different than the cantilever being perpendicular. Doesn't that Bosch laser level work vertically as well? I could definitely envision someone shooting it right on the cantilever, adjusting azimuth until it paints it perfectly. Now that would be something I could get behind. I guess it depends how 'fine' the projected laser line is though.