Classic Sig. motor noise

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Hi, sorry to leave you hanging here. Unfortunately, I haven't. I also haven't determined the exact cause (though I now believe it's more accurate to say "causes"). But I DID minimized it somewhat, so I'll share everything I've learned: 1. The problem isn't universal, but it's common across the Classic lineup.

There are threads on several forums, all fizzle without resolution. This one was helpful: https://hifihaven.org/index.php?threads/vpi-classic-iii-noise-issue.9344/ (I actually joined to ask the original poster if he ever solved it. After consulting with Mat, installing a brand new motor and further attempting to isolate it w/sorbothane, the table was eventually sold.) 2. I can't find a mechanical solution. I suspect "lube your motor and bearing" to be VPI's version of "turn your computer off and back on again." Good practice, but it won't solve this issue. Classic plinths are undeniably beefy, but the design simply doesn't impede internally generated resonances. In theory, changing the mass/rigidity to the rack, or adding mass to the plinth itself, should alter its natural frequency. Applying force to the structure that supports the unipivot changed the pitch of the resonance, but NOTHING I tried could eliminate it. If the motor is making noise, the cartridge will pick it up. 3: The noise is acoustic, I think the cause is electrical. After learning that the guy on HiFi Haven installed a brand new motor and still heard the noise, I kinda ruled out internal issues like rotor concentricity and coil winding/air gap irregularity. So I looked at the wiring. My table is older, which means its internal connections are made via plastic twist-on wire nuts. When I went to check those connections, the capacitor between the red and black legs of the motor wiring pulled right out of them. A loose connection there could easily affect the accuracy of the phase shift among the stators in the motor, which is a recipe for noise in an AC motor. So I made sure those wires were twisted TIGHTLY to each other BEFORE twisting them into the nuts. After accomplishing this, the noise was still there -- but it's slightly quieter. (Incidentally, VPI abandoned those el cheapo twist-nuts at some point after my table was manufactured. Motors are now wired up via a small PC board with screw terminals. Perhaps Mat will read this and offer to send me one.) Another improvement - that I'd recommend for EVERYONE. I also made myself a new set of interconnects between the table and phono pre. It's a shielded, twisted-pair cable, terminated so that the signal and return wires are attached to the center pin and outer collar of their respective RCA jacks, but the turntable ground wire is a "pigtail" that connects the LEMO box ground lug to the cable shield at the turntable end, with another "pigtail" connecting the preamp end of the shield to the ground lug on the back of the preamp chassis. This effectively makes the cable shield and tonearm ground one and the same, while the signal return NEVER connects to the cable shield OR the turntable ground. A better explanation here: https://korfaudio.com/blog98

Better connections of the motor wiring and this new grounding setup have seemingly dropped the motor noise closer to the noise floor. Still audible thru headphones, MUCH less so thru the speakers. But it didn't eliminate the problem. I would love it if the VPI folks would share more of what they know about this issue.

Correction: Item #2, above: More fiddling reveals that -- with the motor on, platter steady, stylus on the record surface -- if I place a finger directly underneath the pivot and gently but firmly press upward, the noise changes in pitch. If I adjust the pressure I'm applying with my finger a little, I can make the noise get quieter. But I can't make it disappear. (PS, it's a Classic III Signature, unipivot, no fluid, O.G. tapered 3D arm.) The fact that the noise is only audible when the stylus contacts the record or platter surface made me think the path was motor > plinth > platter bearing > cartridge > signal path. But now I wonder if the oscillation is moving up through the platter, or down the length of the arm from the pivot... or both. Regardless, the motor is the source of the noise. Best to cure it there, right? Again, the motor is solidly mounted. the shaft/rotor don't seem out of place. Wow and flutter isn't out of whack. I feel like it HAS to be electromagnetic in origin: https://en.wikipedia.org/wiki/Electromagnetically_induced_acoustic_noise

Hey, guys. Amazon had a little delay on those super lube products, but over the weekend I found time to clean the old crusty oil off the motor's shaft and then re-lubricated everything as Mat did in the video. The table definitely feels like it's running a little smoother, but unfortunately the motor is still making a noise that's getting picked up by the cartridge. Like I said, it's not loud - it's really only audible under quiet passages, but wondering what else might be done to cure it and get to a truly blacker background. Let me know what you think!

The Classic Signature's plinth is very well damped, but in some isolated instances, the rack/platform in which the table sits can amplify the natural resonance of the motor and reflect it back into the table.

A couple of options:

1. Make sure that the table's feet are snug against the bottom of the table. Do not over tighten them as it will defeat the footer's impedance properties

2. Try a different platform underneath the table. As an inexpensive temporary solution/experiment, try a set of cork coasters under the feet.

3. Make sure that the motor is not loose.

Motor lubrication:

1. Apply a few drops of light viscosity "oil" to the motor shaft located just below the pulley and underneath the brass balance collar. If you have access to a hypodermic needle, filling it with oil will allow you place the oil precisely. If you have a motor controller, run the table at 45rpm for 45 minutes without the belt, otherwise, run it for 60 minutes at 33.33rpm.  No disrespect to VPI, but I am not a fan of their motor lubrication video.

2. If you need to remove the pulley, follow these instructions. The shaft and pulley are secured by a combination of an interference fit along with three grub screws. Loosen all three grub screws and lift the pulley straight up. If you experience resistance, apply some heat (hair dryer) to the pulley to allow thermal expansion. When reinstalling the pulley, tighten "each" grub screw to the point where it just touches the pulley. The next step is to tighten "each" grub screw 1/4 turn. Repeat the 1/4 turn process until each grub screw is snug.

Thanks, Brf. I'll experiment with isloation as a next move. That's definitely a weak spot for me – my gear is in a solid wood credenza that's quite heavy but definitely not "hi-fi approved." Worse yet, I live on the third story of an old, suspended-floor apartment building. Definitely suboptimal, but the view is nice. I may try moving the whole rig to a more massive, rigid spot just to see what happens. In my place, that'll be the kitchen or bathroom counter. I should have mentioned, I did apply the super lube directly to the shaft. (Same applicator Mat used in the vid, the "snout" fits under the brass ring pretty easily.) My pulley is concentric to the point that it's visually difficult to tell that it's moving when the belt is off. No plans to mess with that, except as an absolute last resort. Thanks, will report back!