2. analog
  3. 1381351770

Need Help Troubleshooting Ground Hum

I am finally trying to resolve an issue that has plagued the analog side of my rig for a number of years: I get a nasty buzz/hum when I play records. Although it gets louder as I crank up the volume, it is not subtle. It sounds something like the kind of buzz you sometimes hear on PA systems. I am assuming it is a ground issue, although I don't know how to solve it.
You can look at my system page to see my rig. Relevant details: I have a SOTA Sapphire turntable feeding into a Bottlehead Seduction phono preamp. The preamp, in turn, is connected to a Manley Shrimp preamplifier.
If memory serves, I did not always have this hum in the system. I think that at first cropped up a bunch of years ago when I physically rearranged my electronic components.
The hum is always there, but only on the analog side. It gets louder when I switch the turntable on. A couple of days ago, I tried rearranging some of the components and moved the preamp further away from the turntable. It didn't get rid of the hum, but I noticed for the first time that the hum actually gets softer (while the turntable platter is rotating) when I touch the top plinth (nonmetallic) of the turntable!
I understand that these kinds of hum issues can be notoriously difficult to resolve, but if somebody can suggest troubleshooting steps I'd be extremely grateful.
Thanks, guys!
rebbi
jameswei
883 posts
 
I used to have a VPI turntable with a PLC power line conditioner that generated enormous interference (hum). I could only use it be placing it as far away as the turntable's power cord would allow.

Where is your turntable power supply located?
williewonka
3,072 posts
 
When you changed the components around did you change the power cables on any components? One of the power cables might have a less than optimum ground that can cause hum. Is connected to the phono stage.

One thing I did on my system was to ground every component chassis/case to one single ground point on my power supply.

Even though I did not have a hum at the time, the resulting reduction in noise was noticeable.
fromunda
146 posts
 
Try lifting power cords off of speaker cables. Also touch all connections in back of your system. You can sometimes isolate the problem doing this. Sometimes wires are just crossing over each other or are just too close to each other.
hevac1
812 posts
 
I had to move my Phonostage away from my preamp and my dac both caused a loud hum when playing records. It all stared when I purchased a new dac and had to make room for it. I moved equipment around to make it more convenient and keep my analog separate from digital. That ended up giving me your same issue. I placed my Phono on top of my TT dust cover turned all on and no hum so I put it on its side next to the TT where it now live happily with the rest of my system.
rebbi OP
1,326 posts
 
Mattmiller,
Do you mean run a wire from the phono pre to the preamp unit, or something else?
More to discover