2. analog
  3. 166562-151430

Ground Wire

The tonearm cable is plugged into RCA input of the phono stage. The tonearm ground wire is connected to the ground post of the same phono stage. The first RCA L/R outputs of the phono stage are connected to a pair of mono blocks. There is no hum I could hear coming from the speakers connected to them. The second L/R outputs of phono stage are connected to the line input of the integrated amplifier that drives a second pair of speakers. That's where the hum is quite audible. That integrated amplifier also has the ground post. I wonder if I could get rid of the hum by connecting the phonostage's ground post with the ground post of the integrated amplifier. What kind of wire should be used to connect two ground posts of two different preamplifiers? The units are at least 8 feet apart. 
esputnix
mijostyn's avatar
mijostyn
8,227 posts
 
You are probably forming a ground loop somewhere. Try floating the ground on the integrated amp. 
anthonya
126 posts
 
 touch around using bare hand and bare footed until the hum changes that will indicate that area have grounding issues 

possibly 2 amps have ground thus causing a loop. try disconnect rca  the mono block first? and see if the integrated amp still hum

also one possibility.. rca ground is loose try clean or tighten it. or change input channel. or change cable. 

just educated guess. but should be easy to solve with enough fiddling and touching. 


pragmasi
212 posts
 
Connecting the phono grounds may work, but it shouldn't be necessary... are all the amplifiers plugged into the same outlet? If not try that first.
fiesta75
1,378 posts
 
You've definitely created a ground loop. Everything should be to one outlet on the same line. Avoid different power lines at all cost. Ground problems are TRICKY. You might want to look into a ground block. 
itsjustme
681 posts
 
Very likely a ground loop complex topic why don’t you Google and read up on ground loops and then do a bunch of experiments to identify it and eliminate it also how are you driving mono block amplifiers with a phono stage and no volume control in between them seems to me you’re leaving something out of this
More to discover