Hi
Just picked up an SN3. Hooked up my turntable and earthed it to the amp. Sounds fantastic but…
When the turntable is plugged in and the wall socket is switched on - the turntable itself does not have to be switched on - there is an audible hum through the speakers. When I turn the turntable plug off at the socket the hum stops.
Has never experienced this issue with my Uniti 2 but appreciate the SN3 is a far more sensitive creature.
Any ideas on how to remedy this?
Thanks
You likely have an Earth Loop, somehow. What is the Turntable, may we ask…?
You say when you turn the Turntable plug off…? But leave the plug in the socket…? Where are you in the World…?
And following on from that, what else is connected?
Nothing at the moment - I just hooked up the turntable. If nothing is connected to the SN3 and the TT is switched on (but not hooked) at the mains there is a hum.
It’s a Pro-Ject X1 - not cheap but certainly not high end! I plan to upgrade. Would it be that?
I’m in the UK.
Ok, so at least I understand your mains wiring… !!!
Check the Mains plug of the Project TT. Does it have an earth lead…?
Does the TT have a separate earth lead, too…? Unplug the TT and check for continuity between the 2 earths. Is there a circuit…??
The norm on TT’s (such as say, on a Linn LP12), is for the earth from the arm to not be linked to the mains earth. This can then go to the amp/preamp without issues.
The mains plug is not earthed - also it’s an adaptor. The two earths are in the RCA cable if that makes sense so I have hooked up to both turntable and amp. If if I disconnect either earth connection the hum gets worse. Should mention the RCA cable is detachable from the turntable.
Right… Making no sense to me, sorry.
If the TT is new or recent, I would contact the dealer who supplied it. Something is not right…
Can only think that the TT’s cart is picking up interference from the motor. What’s the cart - MM or MC…?
Ok no worries!
The turntable has been fine through a Stageline into my Uniti 2. No hum at all.
Ok, maybe its the SN3 then…?? Again, if new/recent, go to your dealer…
You are still using a Stageline - ? Check all its connections, asap.
A poor or missing earth could explain all this… 
No I plugged straight into the SN3.
Thanks for your advice.
This…??
I have run Rega (Planar 2)and Linn (LP12) TT’s with a range of Naim Preamps, without any such problem. The earth from the arm goes to the pre. The TT motor is earthed via its mains plug. This is in the UK.
Yes that!
You just picked it up…? New…?? Call your Dealer…!!!
It’s a Grade A so might have issue then but new to me.
I think its the lack of signal ground to mains earth connection on the SN3 compared to the Uniti 2. This can cause issues with the switching supply your Project TT uses. Try connecting a piece of wire between the SN3 ground post and the outer of a DIN socket and see if this stops the hum.
Still same. Call your Dealer… Do Not Pass Go, Do Not Collect £200… 
