Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums > AC Power and Grounding
Galvanic isolation of all three pins in XLR vs ground lift
Miguel Dahl:
This might be a stupid question, but I'm curious about the difference.
If running a signal line to several active speakers, where one of them is powered from a different outlet with a different ground potential. Is there a difference in using a galvanic isolation between all three XLR-pins and just "lifting" pin 1? on the signal feeding the speaker on a different ground potential relative to the ground potential to where the signal originates from?
Pete Erskine:
--- Quote from: Miguel Dahl on August 21, 2018, 02:09:45 PM ---This might be a stupid question, but I'm curious about the difference.
If running a signal line to several active speakers, where one of them is powered from a different outlet with a different ground potential. Is there a difference in using a galvanic isolation between all three XLR-pins and just "lifting" pin 1? on the signal feeding the speaker on a different ground potential relative to the ground potential to where the signal originates from?
--- End quote ---
Depends on the input. if it is transformer isolated no problem. It is much more likely that you will need to have an isolation transformer in the line.
Miguel Dahl:
--- Quote from: Pete Erskine on August 21, 2018, 02:58:58 PM ---Depends on the input. if it is transformer isolated no problem. It is much more likely that you will need to have an isolation transformer in the line.
--- End quote ---
Thanks, but I feel it didn't answer my question regarding what "answer I seek", the difference between a 3p iso and just a pin one iso.
Pete Erskine:
--- Quote from: Miguel Dahl on August 21, 2018, 03:11:28 PM ---Thanks, but I feel it didn't answer my question regarding what "answer I seek", the difference between a 3p iso and just a pin one iso.
--- End quote ---
A transformer is a 2 pin iso. Lifting pin 1 just disconnects the ground but if your equipment is NOT transformer isolated, pin 1 does not really isolate it, particularly if it is and electrally balanced I/O.
If you have transformer and pin 1 lifted it is a 3 pin iso.
John Roberts {JR}:
--- Quote from: Miguel Dahl on August 21, 2018, 02:09:45 PM ---This might be a stupid question, but I'm curious about the difference.
--- End quote ---
perhaps... do you have a problem?
--- Quote ---If running a signal line to several active speakers, where one of them is powered from a different outlet with a different ground potential. Is there a difference in using a galvanic isolation between all three XLR-pins and just "lifting" pin 1? on the signal feeding the speaker on a different ground potential relative to the ground potential to where the signal originates from?
--- End quote ---
If the active speakers have a well designed input there will be no difference, if they don't the answer is not to float the ground (pin 1), but maybe see if the speakers float in the canal out back.
JR
Navigation
[0] Message Index
[#] Next page
Go to full version