Hi, VPI folks.
I'm looking for advice on what to do about a background noise issue. In a nutshell, I hear the motor running through my speakers (and more-so through headphones). It's mostly noticable in quiet passages/lead-in/runout. So it's tolerable (I've been living with it a while) but it definitely needs to go away.
Troubleshooting to date:
It goes up and down with the volume control.
Different inputs, amps, speakers vs phones, all investigated. It's definitely the turntable.
It crosses a range of frequencies (according to an iphone spectrum app). There are "humps" around 180Hz and 300Hz (or perhaps, 300 rpm?) but no big spikes at 60 or 120Hz.
It's ONLY audible when the motor is running AND the stylus is down on the record surface.
It's audible REGARDLESS of whether the belt is attached, so that rules out the platter bearing.
I replaced the capacitor to cure the dreaded startup "pop." I lost the old one.
Full disclosure, I'm WAY overdue for routine maintenance. I bought the table used in '19 and I've never lubed the motor. The previous owner clearly did, because a bead of what looks like old motor oil has slowly crept up the shaft and formed a bead between the top of the motor assembly and the pulley.
So... have I let this motor go to hell through neglect? I'm fairly handy -- can I clean/fix it without breaking whatever damping system is (supposed to be) keeping motor vibrations away from the platter? Or is this a repair shop kinda thing?
Thanks!
No worries! Thank you for the extremely detailed and thoughtful reply.
Did you ever resolve this problem? I am experiencing the same thing with my Classic 3.
Thought I'd take a moment for an update. Followed Brf's suggestions... 1. The feet are "just" snug against the bottom of the table. I even loosened them and re-snugged, listening to each position. None of that had an effect on the noise. 2. I tried cork under the feet. Also, no effect. I haven't yet tested the table on the more rigid kitchen counter - I'll probably tackle it over the long weekend. That said... if the theory is the resonant frequency of the motor = the natural frequency of the rack+turntable combo, then changing the mass and/or damping of that system should do.... something. So I placed both palms under the turntable and leaned on it, essentially adding my body weight to the rack --- also, I pressed down on the turntable at various points without touching the rack. None of affected the noise in any way. 3. So... the screws on that round mounting plate are tight. If I try to "wiggle" the pulley there's little perceptible play, if any. (And as I said, without the belt it's actually hard to tell visually if the pulley is spinning. It *looks* very concentric.) If I turn the pulley, it feels a bit like turning the rotary switch for a stepped volume control. I assume this is normal cogging action in a non-coreless motor. So I don't think anything's loose. Now I'm starting to wonder if the issue is acoustic noise that's getting induced electromagnetically. i.e. are the motor's coils humming? I did the capacitor swap to get rid of the "pop." Should I try a different cap? Inspect the MOTOR's ground? Or get in there from below and add additional damping to the motor somehow? If someone from VPI could share a circuit diagram for the motor (it's 3-phase, right?) and include the right value for that cap, I'd appreciate. Other advice is also welcome! Thanks and happy holiday.
Hi Mike, very happy to have you in the VPI family and hoping to get you all squared away. No worries nothing we can't try to fix with some maintance and other fun tricks.
Check this video maintance video first to see if it helps because gunk in the motor could very well be doing it. Let us know and we can keep going from there!