Bottlehead Forum
Other Gear => Phono => Topic started by: booangler on January 11, 2011, 01:46:58 PM
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Hi all,
Basic question regarding grounding wire on modern turntables.
So we have the left and right channel cables that exit the turntable to connect phono inputs on the pre-amp, the receiver, or the integrated amp. At the same time there is usually a ground wire that exits the along side the outputs. Where does the ground wire connect to?
Thanks, Alan
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to the chassis of your receiver /preamp or intergrated amp-there should be a grounding nut of some sort on your preamp it may be a knurled nut or a pushbutton style with a hole in the side that traps the wire or 1/2 of the spade-some preamps did not have one such as the dynaco pas 3x scott intergrated amps and others--if you don't have a obvious place to hook the ground wire you can loosen a screw and attach it there-i have temporarily used a wire with alligator clips on both ends--thats temporarily--you can make one easily -go to the hardware store and get a knurled nut /a screw to fit and a nut and lock washer-drill a hole and install -
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Ok,
So I worded my original post completely wrong. I am wanting to know where the other end goes. Does it connect to the tonearm, the motor, or the the two ground wires coming off the cartridge?
Thanks again
Alan
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If the tonearm is grounded to the chassis of the TT your grounding wire can go to either. Mainly it should be attached to the arm. Some arms have an integral ground were the ground wire is attached to one of the RCA jacks' outer conductor.
With grounding problems try one at a time then combinations till you get the lowest hum possible. Maddening but it works.
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If the tonearm is grounded to the chassis of the TT your grounding wire can go to either. Mainly it should be attached to the arm. Some arms have an integral ground were the ground wire is attached to one of the RCA jacks' outer conductor.
With grounding problems try one at a time then combinations till you get the lowest hum possible. Maddening but it works.
Grainger, I am not having a grounding problem, I am trying to understand the system a little better. If I understand this correctly the grounding wire goes to the arm. But what happens to the grounds coming off of the cartridge?
Alan
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The idea is that there will be current between the chassis of the preamp and the turntable. This is usually due to capacitance between the power line (connects to the turntable motor and wiring, and to the preamp power transformer primary) and the chassis. You want to keep this current out of the signal grounds from the cartridge, so you connect the chassis to each other with a heavier wire, and you run the signal grounds to a single point, usually right at the input of the preamp.
If this current ran through the "ground" of the interconnect, its non-zero resistance would create a hum voltage that the preamp would see as part of the signal - it can't tell the difference. We call this a "ground loop" but it's not usually due to magnetic fields as the textbooks say, it's usually the capacitive coupling to the power line.
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The cartridge generates a balanced output. The right and left do not have a common ground. As the right positive lead swings positive the negative lead swings the opposite. So the positive and negative of each channel are wired to the center and shield, respectively, of the RCA cables of the arm or table.
There is a ground often from the table chassis that needs to ground to the phono stage. It can be from the arm as well.
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Alan, the short and quick answer!
The tonearm ground goes to the chassis of the preamp, the signal goes to the center of the RCA connector and the signal ground goes to the outer shell (ground) of the RCA connector.
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Alan,
I see that you have the Rega P1. This TT doesn't have a grounding wire, it is apparently grounded internally (though I've never understood how).
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i have a acoustic research AR XA-- the ground wire from the tone arm is connected through the left common-i have changed it as i rebuilt the plinth etc but it had no hum issues and caused me a short period of puzzlement as i was looking for the ground wire-but after removing the" high tech cardboard bottom" i saw the answer--