Ground cable from turntable, where does it go?

[Cygnus]

Hey guys I want to buy a Technics SL1200MK2. I have a phono preamp from TheSource which has two sets of RCA jacks, one for in and one for out. That's all that's there.

Now, I want to buy the turntable, and the cartridge, but I am wondering where the ground cable goes from the turntable, since I don't have a ground plug or cap, whatever you call it, on my Denon AVR.

 

[Cygnus]

Uh oh, I may have made a mistake when I bought that preamp didn't I, since it doesn't have a ground post?

 

[highfigh]

Uh oh, I may have made a mistake when I bought that preamp didn't I, since it doesn't have a ground post?

If you have a multi-meter, measure the resistance from the cable shield to the metal case of the preamp. If it's not connected, look on the bottom for a ground screw, tab or something like that. Also, you can get a ground tab and mount it on the Denon receiver, using one of the unpainted bottom screws. The painted ones aren't the best choice. Don't just use a longer screw if you use one of the screws on the Denon unless you remove the cover to make sure the added length won't reach the circuit boards or other electronics.

 

[Cygnus]

If you have a multi-meter, measure the resistance from the cable shield to the metal case of the preamp. If it's not connected, look on the bottom for a ground screw, tab or something like that. Also, you can get a ground tab and mount it on the Denon receiver, using one of the unpainted bottom screws. The painted ones aren't the best choice. Don't just use a longer screw if you use one of the screws on the Denon unless you remove the cover to make sure the added length won't reach the circuit boards or other electronics.

I got basically a response on another message board that I could take the ground cable from the Tech 12, and just hook it on to one of the screws on my denon as you have also suggested.
1. Why does the screw length matter?
2. Why would I not want said screw to touch any circuit boards?
3. Could I use a screw on the side of the pre amp instead of one on the receiver?

 

[highfigh]

I got basically a response on another message board that I could take the ground cable from the Tech 12, and just hook it on to one of the screws on my denon as you have also suggested.
1. Why does the screw length matter?
2. Why would I not want said screw to touch any circuit boards?
3. Could I use a screw on the side of the pre amp instead of one on the receiver?

As I posted, screws that are too long could possibly come into contact with the circuitry in the receiver. If that includes the power supply, it will damage that and could be dangerous. It will also void your warranty. The chassis is the ground reference and any connection to another connection is a short circuit.

2. Why could it be OK for a screw to touch the circuit boards? If they had designed it for that, it would have been made that way.

3. The ground path needs to be continuous from the source to the receiver in order to reject the most noise. If the case of the preamp isn't connected to the audio ground (the cable shield), you haven't actually grounded it because the ground reference is the receiver's chassis.