fixing the pre-amp noise

Hi Ching,

I have bought a Mcintosh C28 (110V).  When I connected it to my gears, I found that there was a electrical noise coming from right speaker.  The left speaker is quiet.  I can still hear the noise when I stand back around 4-5 feet.  Any idea can reduce that noise.  Thank you.

yes, exactly what you said.  It is deeee...deee sound.  But it is a Mcintosh pre-amp.  How do I ground it?

I did diy amp before.  But I am a diy beginner.  So it is hard for me to trace the source.  Well, now I am testing different senario which part cause the noise.  let me update later.  thanks Alcat