I have always thought that ground "lift" was in regards to the signal ground. If you had 2 plexis "daisy chained" together, you would lift the input ground of the second amp head, and that would help with noise from a ground loop.
But I read/hear so often about lifting the MAINS ground to alleviate ground loops. Below is a quote from some Dynaco Stereo rebuild/upgrade info. Not only does the guy recommend lifting the mains ground for noise reasons, but he says it really is not necessary. Is this right.? Has my lack of education/knowledge caught up with me again.?
Thank You
"Install ground isolating adaptors (available at any hardware store) on any component
that has been equipped with three prong power plugs. Power up and note the effect. Has
it been eliminated (or reduced)? If there is an improvement keep the adaptors
permanently in place. (Personally, I always remove the ground connection from all of
my components since with high end equipment utilizing power transformers, there is
virtually no danger whatsoever and it eliminates a continual source of hum generating
problems)"
Ground Lift
Moderators: pompeiisneaks, Colossal
Re: Ground Lift
Mains ground is a safety feature, while signal/audio ground only is a reference for the audio signal.
If you lift mains ground you are doing it wrong. Electrical faults that find their way to the chassis will head towards ground in the wrong direction, through the instrument cable and in the users direction, which isn't very good from the users perspective.
The correct way to remove hum would be to use an isolation transformer or like you said lifting the signal ground to amp number two.
It is a good practice to stay critical of things on the internet. Not everything on it is smart or correct when considering health and safety issues.
I hear there's even videos showing people jumping pickup trucks and setting themselves on fire on this here internet thing.
If you lift mains ground you are doing it wrong. Electrical faults that find their way to the chassis will head towards ground in the wrong direction, through the instrument cable and in the users direction, which isn't very good from the users perspective.
The correct way to remove hum would be to use an isolation transformer or like you said lifting the signal ground to amp number two.
It is a good practice to stay critical of things on the internet. Not everything on it is smart or correct when considering health and safety issues.
I hear there's even videos showing people jumping pickup trucks and setting themselves on fire on this here internet thing.
Re: Ground Lift
What was described is more accurately termed "defeating the safety ground." There is only one safe way to do it in permanent or semipermanent installations, which is to remove the ground connection from all interconnected components EXCEPT ONE, then hardwire all the chassis' together using heavy ground wire to DEDICATED ground connections. Electricians are involved.
Interestingly, this alone usually doesn't do the trick. You also need a ground lift in each piece of gear. This DOES NOT lift the safety ground, rather it disconnects the circuit ground from the chassis ground. For that to work, every input and output has to be isolated from the chassis and no ground except the safety ground can be directly connected to the chassis.
Interestingly, this alone usually doesn't do the trick. You also need a ground lift in each piece of gear. This DOES NOT lift the safety ground, rather it disconnects the circuit ground from the chassis ground. For that to work, every input and output has to be isolated from the chassis and no ground except the safety ground can be directly connected to the chassis.