Tips requested to remove (earth) hum in my system.

flez007

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Aug 31, 2010
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I am getting some residual hum comming out from both a RtR deck and turntable that share a common preamp - I already had a ground wire from the Technics 1500 to my previous tape preamp to solve this, but now it is more audible thru my new preamp.

I will try re-routing cables and place this preamp in different positions to try to solve it, any other tips you all think I should try? (I have all Sunday to fix it) :)
 

mep

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Apr 20, 2010
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Fernando-Have you tried running a ground wire from your preamp ground back to the the screw that holds the wall plate on your ac recepticle?
 

flez007

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Aug 31, 2010
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Fernando-Have you tried running a ground wire from your preamp ground back to the the screw that holds the wall plate on your ac recepticle?

Nop..will try that, thanks mep!
 

ack

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May 6, 2010
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I am getting some residual hum comming out from both a RtR deck and turntable that share a common preamp - I already had a ground wire from the Technics 1500 to my previous tape preamp to solve this, but now it is more audible thru my new preamp.

I will try re-routing cables and place this preamp in different positions to try to solve it, any other tips you all think I should try? (I have all Sunday to fix it) :)

Hum usually implies a ground loop; star-grounding goes a long way (all components plugged into the same strip that actually implements star grounding), as does making sure there is actually good ground contact on all components' IEC receptacles; to a lesser degree, a good idea to run shielded power cords to and around sensitive components.
 

Robh3606

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Aug 24, 2010
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If you have a cable box in there somewhere also check the outside ground spike connection. I had maintenance done and the tech for some reason disconnected the ground wire from the splitter to the spike. All was fixed when I reconnected the ground. Like the others have said star grounding to a real hard ground can work wonders.

Rob:)
 

mep

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I picked up on Roger's take on grounding by buying a piece of copper buss bar, drilling and tapping some holes, and then running all grounds to the buss bar with one wire from the buss bar going to the screw on the outlet where the preamp is plugged in.
 

Ki Choi

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May 13, 2010
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Hi Fernando:

If your hum-fest started with addition of the KC preamp, I would suggest you try to lift the ground of KC's power supply by use of a cheater plug. You might find you also need to do the same to your preamp.

Ki
 

flez007

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Aug 31, 2010
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Hi Fernando:

If your hum-fest started with addition of the KC preamp, I would suggest you try to lift the ground of KC's power supply by use of a cheater plug. You might find you also need to do the same to your preamp.

Ki

It does Ki, actually, floating the earth plug is my number 1 test, problem is that I am listening to the Mach2/Stello/Havana setup and can't get started :)
 

ack

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Be careful about lifting ground; see the following article on ground loops: http://en.wikipedia.org/wiki/Ground_loop_%28electricity%29

Low current wiring is particularly susceptible to ground loops. If two pieces of audio equipment are plugged into different power outlets, there will often be a difference in their respective ground potentials. If a signal is passed from one to the other via an audio connection with the ground wire intact, this potential difference causes a spurious current through the cables, creating an audible buzz at the AC mains base frequency (50 or 60 Hz) and the harmonics thereof (120 Hz, 240 Hz, and so on), called mains hum. Sometimes, performers remove the grounding pin from the cord connecting an appliance to the power outlet; however, this creates an electrocution risk. The first solution is to ensure that all metal chassis are interconnected, then connected to the electrical distribution system at one point (often referred to as a "single-point ground"). The next solution is to have shielded cables for the low currents, with the shield connected only at one end (this, however, increases the possibility of radio frequency interference (RF) since the shield may act as an antenna).
 

flez007

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Thanks all for your feedback, Looks it is a defective part in the preamp that will be shortly replaced :)
 

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