2. amps-preamps
  3. 154659-435

How to guarantee to lower noise- ground loops in your system

I have been through many problem area where noise in the  audio chain was a problem.
my friend Who is a Electrician solved the problem . All too many times people add a dedicated 20 amp circuit 12awg is standard 11-10awg even better lower resistance , also most important 
you need a Isolated dedicated ground, this is totally insulated right back to the earth ground in the 
breaker box this will dramatically lower your noise floor and remove ground loop problems .many people just put a dedicated line and think 
that’s it ,not so, if you are going to go through the trouble, then  for maybe $100 more the isolated dedicated ground  to the dedicated circuit is a must. I can tell you without question .
my Audio has a noticably quieter background .in songs i now hear low level musical artifacts like reverb off a guitar fading cymbals and clearer seperation of instruments .well worth the effort .Hopefully 
this will help others .this is a essential system upgrade .
128x128audioman58

Showing 3 responses by almarg

almarg's avatar
Ag insider logo xs@2x
almarg
9,670 posts
 
As I'm writing this I'm also playing my stereo that has a phono section, a line preamp and dual mono power amps that all have switches to lift the chassis grounds. Those mono amps always play with the ground lifting switches in the lift position, because they sound better that way, in my system that has extremely sensitive speakers.

As far as I am aware what those switches do in all of the audio components which provide them is to isolate their internal circuit ground from the chassis, while not affecting the connection of chassis to AC safety ground.  And consequently setting those switches to the lift position does not defeat the intended purpose of the AC safety ground, which is to cause the breaker to trip if an internal short develops between the AC line voltage and the chassis.

Regards,
-- Al
 
almarg's avatar
Ag insider logo xs@2x
almarg
9,670 posts
 
... your illustration only shows a 5 amp current draw on a 20 amp circuit breaker, there in not any way 5 amps could trip a normal 20 amp circuit breaker.
Yes, and that’s exactly the problem, as page 29 of the reference very clearly explains. In the event that a fault in a component causes the AC line voltage to come in contact with the metal chassis of the component the breaker is supposed to trip to prevent the possibility of someone being shocked or electrocuted. But with the grounding configuration described by you and on page 29 of the reference the breaker will not trip, leaving the chassis of the component energized at 120 volts (or whatever the line voltage is in the particular country). Thus defeating the fundamental purpose of the safety ground wiring.

If however there was a 5 amp short like in the page 29 schematic there is no reason that it would not be safely discharged to ground.

It would be discharged to ground, but not safely because the chassis of the component would continue to be electrified at the full AC line voltage. I’m not sure how that can be explained any more clearly than it is on page 29 of the reference.

Regards,
-- Al


almarg's avatar
Ag insider logo xs@2x
almarg
9,670 posts
 
The previous comment by Cleeds is 100% correct. For further explanation see page 29 of the following excellent paper, written by a distinguished expert on such matters:

https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

Regards,
-- Al

More to discover