Fitting a resistor on the signal ground “lifts” it from the chassis earth. If you can insert a 10-100 ohm resistor between your signal ground and safety/chassis ground, this will stop the hum if it’s that causing the earth loop.
Fitting a resistor on the signal ground “lifts” it from the chassis earth. If you can insert a 10-100 ohm resistor between your signal ground and safety/chassis ground, this will stop the hum if it’s that causing the earth loop.
“Music has always been a matter of energy to me, a question of fuel. Sentimental people call it inspiration, but what they really mean is fuel. I have always needed fuel. I am a serious consumer. On some nights I still believe that a car with the gas needle on empty can run about fifty more miles if you have the right music very loud on the radio”
Hunter S Thompson
Source
SW1X Universal Music Server UMS I Signature with Power Supply Unit PSU I Signature
SW1X USB II
SW1X DAC III Special
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BK Electronics XLS400FF Sub.
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Will still do the same job though, you just need that bit of resistance in the signal ground, doesn’t matter which end of the cable it’s at.
Yes it would be the same with my pre- a wooden box with Tribute AVC’s inside.
“Music has always been a matter of energy to me, a question of fuel. Sentimental people call it inspiration, but what they really mean is fuel. I have always needed fuel. I am a serious consumer. On some nights I still believe that a car with the gas needle on empty can run about fifty more miles if you have the right music very loud on the radio”
Hunter S Thompson
Location: London/Durham
Posts: 6,894
I'm Lawrence.
The interconnect is a cable between two components, in this case preamp and amp. It has two wires, one signal, one ground. The point of this earth lift is to add between 10 to 100 ohms to the ground cable to stop the hum. Think about it, it doesn’t matter which end of the wire you put the resistor, if you measure the cable with a multimeter you will get the same ohms reading whichever end you’ve put the resistor in.
Make sense?
“Music has always been a matter of energy to me, a question of fuel. Sentimental people call it inspiration, but what they really mean is fuel. I have always needed fuel. I am a serious consumer. On some nights I still believe that a car with the gas needle on empty can run about fifty more miles if you have the right music very loud on the radio”
Hunter S Thompson
Location: London/Durham
Posts: 6,894
I'm Lawrence.
'Fraid not, I agree it changes the resistance between the ground at one end and the passive case at the other (which is not earthed), but is the important measure not the resistance between the grounds in each joined component which is still equal to the resistance of the cable?
In fact I don't understand how changing the resistance between grounds eliminates hum anyway, might have to go back to first principles on this...
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Source
SW1X Universal Music Server UMS I Signature with Power Supply Unit PSU I Signature
SW1X USB II
SW1X DAC III Special
Audiolab 6000 CDT transport
Amps
Pre amps -- Hi fi Collective twin mono ladder stepped attenuator, with Charcroft Z-foil and silver wired. And First Watt B1 active no gain buffer.
Power amps -- Welborne 45 SET monoblocks 1.8W / Decware Taboo 6W / Elekit 300B TU-8600SVK plus further improved components 9W / ICE Power 1000W
Speakers
Highly modified Endorphin P17 open baffle speakers containing both vintage and modern alnico drivers and paper cones. All silver wired - 8" Cube Audio FC8 full range drivers and vintage 15" Altec VOTT 416 bass drivers. All sat on Townsend Audio Podium seismic isolation platforms.
BK Electronics XLS400FF Sub.
Cabling
Silver mains cables, interconnects and speaker cables by SW1X
Headphones
HRT HeadStreamer and SennHeiser HD650 headphones
A ground loop is just that: a circular conducting loop, which when threaded by an external magnetic field (due perhaps by leakage from a transformer, or from being in close proximity to mains cables) will cause a 50Hz current to flow in it. Increasing the resistance of the loop by inserting a 10R resistor (so called earth 'lift'), will greatly reduce the size of this induced current and hence the effect it will have on the audio circuitry.
Barry
Also, using a passive with transformers will also break the earth loop.
I had a passive once which did just that.
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I agree, I think Ali is suggesting that the resistor is inserted in the 'ground' connection out to the output sockets.
As far as an earth lift goes in an earthed case system, the extra resistance between the signal ground loop and the earth loop forces any current that is flowing to flow in the earth connections between cases, rather than the signal connections, thus reducing the 50Hz currents to virtually zero.