Grounding A Preamp

Licoricepizza,
Question:
If you select, say, CD for the listening input on the preamp, is the buzz present?

If not and it is only present when the preamp listen selector switch is set to phono..... there may very well be a problem with the preamp.

I have a NAD 1155 preamp with a nasty buzz in the phono stage.

It's not a phono grounding issue, because I checked that.

How did you check that?

If you disconnect the TT from the NAD (ics as well as TT ground wire) is the buzz still present?

Should I just run a wire from the preamp to a electrical outlet screw, or what? I am at a loss.

If the NAD has a 2 wire cord and plug I would not advise that. And I do not believe it will make any difference in regard to the buzz.

01-29-09: Licoricepizza
The TT does have 2 prong plug.

How about the NAD preamp?

To this untrained ear, it sounds like a 60Hz buzz, like you'd get from a fluorescent light, or a wall-wart transformer.

Is the buzz sound being heard from the speakers?
Or is the sound, a mechanical sound, coming from the preamp itself?

01-30-09: Licoricepizza
The preamp also has a 2 pronged plug. The buzz is coming from the speakers, and is volume dependent

Well if I understand you correctly at on point in your trouble shooting you isolated, disconnected, everything from the inputs of the preamp and the buzz was still present. Correct?

The buzz varies with gain of the volume control.

Did you check the ics that connect the preamp to the power amp for corrosion both ends RCA plug to RCA jacks of the equipment?

Unplug and plug them back in several times and see if that helps.

Try a different pair of ics.

When the ics are plugged in try gently moving the ics plugs at the jack connection at the preamp first then at the power amp.

When you touch the preamp with your hand and the buzz goes away, jmho, that sure sounds like a signal ground problem to me.

Your body is not acting like an earth ground. I think it is working more like a capacitor. Maybe an electronics EE will comment more on that one.