Possibly your cables are not shielded.
What's making my system hum?
I have a Swagman Labs linear power supply feeding the Rega TT-PSU turntable controller. Lately I have noticed a hum audible through the speakers when turned up to about 50 percent of full volume. When I switch the Rega TT-PSU back to its wall-wart power supply, the hum disappears. When I move the power supply away from the TT-PSU, the hum also disappears.
The rest of my system consists of a Rogue Audio Ares phono stage, a VTL IT-85 integrated amp, Vandersteen Treo CT speakers, and various boxes (computer, DAC, linear power supply) to play digital music. There's virtually no hum when the VTL is set to any source except the turntable.
The obvious solution is to keep the power supply and turntable controller farther apart, but I can't help wondering what's causing this. Anyone have any ideas?
The rest of my system consists of a Rogue Audio Ares phono stage, a VTL IT-85 integrated amp, Vandersteen Treo CT speakers, and various boxes (computer, DAC, linear power supply) to play digital music. There's virtually no hum when the VTL is set to any source except the turntable.
The obvious solution is to keep the power supply and turntable controller farther apart, but I can't help wondering what's causing this. Anyone have any ideas?
14 responses Add your response
So you know that the linear power supply is the culprit. Probably from the transformer. Grounding can be a problem with low level turntable cartridges . Your LPS probably has a 3 prong plug whereas the standard ( wal-wart) has only 2. Try reversing and/or lifting the plug of the linear power supply at the wall with one of those 2 prong adapters. ozzy |
Thanks for the suggestions, folks. lowrider57, the cables are all pretty good quality, including the one between the power supply and TT-PSU. ozzy, the cart is a Rega Apheta 2 moving coil. I tried running a ground wire from the tonearm to the grounding terminal on the phone stage and only got more hum. I'm a little leery of flipping hot and neutral on the power supply but may give it a try if I can find a cheater. |
Ozzy is sort of there with lifting the grounds. Look at your systems earthing as a whole, there should only be one earth point to the mains, as earths are carried between all the components via the interconnects. Either the preamp or the source or the poweramp should have that one earth to the mains. You run the risk of an "earth loop" via your households mains cabling if you have more than one earth connected to the mains, this "earth loop" can cause mains hum. Cheers George |
georgehifi3,521 posts03-02-2018 1:04am Ozzy is sort of there with lifting the grounds.Ground loops aren’t caused by multiple paths to ground, they’re caused by different potential between those grounds. The proper solution is to get all grounds at the same potential - eliminating safety grounds isn’t a wise shortcut. An interconnect isn’t intended to serve as safety ground, and that’s why components typically have their own safety ground. |
