Hey. I have bought an old Pioneer PL-12D turntable, which is i working order, only problem is that there is a bit of hum. Its not the ground wire since it only hums when i play a record. Any tips or surgestions?
A Ortofon FF 15. I think it was born with this model. I have tried to spin the platter manually with a record on and when i do, there is no hum. So it has to be the motor that causes it.
There is no electrical connection between the motor and the tonearm/cartridge. Where is the noise coming from? Is it physically produced by the table? Or, is it coming through the speakers? Does the noise increase in volume as the record plays or is it a constant level? About how loud is the noise? Can you hear it over the system playing or do you have to be close to the table?
I can hear the hum when i'm close to the turntable. But i can also hear it through the speakers between tracks. It's not very loud, and does'nt increase with volume. I have tried spinning the platter manually and "playing" a record, then there is no hum, but when i turn it on, it starts. I can also feel i slight buzzing in my fingers when i touch the plinth during playback. I have tried removing the ground wire and then there is the normal 5 hz hum, so its not that. It's probably the motor itself, but how can a simple AC motor create that much hum?
Usually when you get that sort of noise through a synchronous motor, there is a line voltage problem. Though your situation would appear to be worse than most, the type of line conditioners made for turntables remove spikes and dirt and resynch the line which normally clears the problem. I'm not sure what to suggest first. I think I would take the table to a friend's house on a different incoming AC line and find out if you still hear the noise from the motor when playing a record. If the hum is the same amount, then the situation is falling within the motor. Some motors, particularly on lower priced tables which the PL12 was, allowed a fair amount of hum to be present in the motor. If this is what you are hearing, I have no way to tell. The hum through the speakers is probably not related to the hum from the motor and can probably be helped by a good, thorough cleaning of all the contacts on the table. Start with the cartridge pins and work your way to the RCA's on the arm lead. Make sure you take care of things inside the table also.
In general these issues are "hum loops" in which equipment is powered from different outlets, have complex earthing arrangements or bad contacts somewhere. If you can, make a star for mains power and earth (where everything goes back to 1 point, the star centre; often the amp chassis). That might do it (might not).
Earthing and hum problems are well in the lap of the Gods alas
On my machine the hum only occured when the platter was powered / rotating; that's a sign of current / magnetic induction from internal wiring to the phono leads.
Also - worse - the hum got louder for me if I had the platter turning then gently touched the stylus needle oh no! electrostatic coupling too.
Well, check all joints as being good (and inside the headshell), clean all connectors, remove loops in the earthing by using a common star point; if needs be, secure the platter / arm and take the bottom off the deck (it will simply unscrew).
Hey, it's simple in there! If any phono leads are close by the power - separate them. I did a small rewiring and separated them by another 2 inches; nothing difficult - just take care.
All that dropped my hum by 70% - but that last 30% niggled. Had to use some fancy isolation on the PL-12D's power side (got an isolating transformer). That nailed it.
Thank you both. I have tried it at a friends place, and found that the hum-level didnt change. I'll try the clean-up, and see what happens. Thanks again!
