My vinyl equipment consists of a modified Lenco turntable and a Hagerman Cornet3 phono preamp. I have had a long standing grounding issue that is presented as noise from the speakers when I touch the tonearm. As far as I understand the reason for this is quite simple, the power supply that came with Cornet is a wall wart type, with a 2 prong connection. Meaning there is no ground. I have checked that I have continuity from the tonearm all the way to the mains connector on the phono amp.
I must be missing something, how should I get this grounded if the power supply doesn't have a ground pin?
I must be missing something, how should I get this grounded if the power supply doesn't have a ground pin?
Thanks for the reply! On the back of my amplifier? Do you mean the phono preamp or the speaker amplifier? The one on the phono is connected, my speaker amp (Elekit TU-8200) doesn't have a similar ground screw.
As far as I understand the problem is that while I have connection to the ground screw on the phono preamp, the preamp itself is not connected to any actual ground.
For most home audio, it is sufficient for all "grounds" to connect to each other. Except in severe conditions, connection to dirt or power company may not be needed.
Get a set of clip leads, try connecting metal parts to each other. Specifically that tone arm handle to the main amp case. If it works better with a clip-lead, whatever you think is 'grounding' isn't doing the job. (Bad connection, broken wire, rust, paint....)
if touching your tonearm induces noise the tonearm is likely not grounded properly relative to your preamplifier. The important 'ground' is the preamplifier reference ground, not metaphorical earth or the electrical safety ground in the electricity supply (if there is one).
It is not uncommon for the barrel or other parts of the of the tonearm body to lose connection to grounding wire for one reason or another (or not be connected in the first place or even be not metallic/conductive, e.g. some carbon fibre, and therefore not able to shield the signal wires from interference). Check for continuity between the grounding wire and the headshell, finger grip, and body of the tonearm. Note in the case of Rega and some other tonearms the tonearm body ground is integral to one of the signal grounds and not a separate wire.
If there is an electrical ground through the power lead to the chassis of the turntable, then connecting the sections of the tonearm to the chassis ground may work just fine, meaning it often eliminates the contact buzz you described, just as long as it does not introduce ground noise through an earth loop. In fact in the case of an electrically earthed turntable make sure the tonearm body is only connected to the electrical supply earth OR the preamplifier ground, not both.
In a well sorted cartridge/tonearm/preamp setup, only a tiny bit of low pass broadband noise should be audible with with the gain (volume) control at maximum. Any discernible 50/60Hz hum, or any 100/120Hz ripple, or buzz, sizzle or crackle, is indicating less than ideal wiring or screening from an engineering standpoint. It's much nicer to listen to records au naturel without any of those condiments, and quite normally possible.
It is not uncommon for the barrel or other parts of the of the tonearm body to lose connection to grounding wire for one reason or another (or not be connected in the first place or even be not metallic/conductive, e.g. some carbon fibre, and therefore not able to shield the signal wires from interference). Check for continuity between the grounding wire and the headshell, finger grip, and body of the tonearm. Note in the case of Rega and some other tonearms the tonearm body ground is integral to one of the signal grounds and not a separate wire.
If there is an electrical ground through the power lead to the chassis of the turntable, then connecting the sections of the tonearm to the chassis ground may work just fine, meaning it often eliminates the contact buzz you described, just as long as it does not introduce ground noise through an earth loop. In fact in the case of an electrically earthed turntable make sure the tonearm body is only connected to the electrical supply earth OR the preamplifier ground, not both.
In a well sorted cartridge/tonearm/preamp setup, only a tiny bit of low pass broadband noise should be audible with with the gain (volume) control at maximum. Any discernible 50/60Hz hum, or any 100/120Hz ripple, or buzz, sizzle or crackle, is indicating less than ideal wiring or screening from an engineering standpoint. It's much nicer to listen to records au naturel without any of those condiments, and quite normally possible.
Last edited:
Posting a recording of the noise you hear may likely help with identifying the noise mechanism and hence the noise source.
Thank you for your very helpful and thorough responses! As it happens, the contact buzzes have vanished! It seems that while checking, dismantling and reassembling everything I must have fixed a poor contact somewhere. I didn't expect that, since I have dismantled everything a few times before and each time getting the same noises after putting things back together. So I assumed there was a different problem.
I still have a bit of a background hum, but it is not audible on listening levels unless you put your head next to a speaker. With raised volumes it is easily audible. Since it doesn't bother listening I think I will let it be for now.
Thanks for all the help!
That's great. Sometimes painted or anodised surfaces don't make a good electrical connection unless carefully joined.
Often the last bit of hum in a turntable is due to the unscreened wires where they exit the rear of the tonearm. It is often possible to install a grounded metal shield around the wires that doesn't affect their flexibility but reduces or eliminates the hum field around them and hence the noise picked up.
Finally many (most?) RCA interconnect cables, including those supplied connected to turntables, do no have 100% screen cover and will therefore allow some hum pickup (and other EMI / RFI !) along the cable, and potentially acoustic interference due to microphonic behaviour.