Buzzing noise from T400 on advanced dock

[elthinkpado]

Hi.
I just received a new T400 and for some reason, when I dock it into my advanced dock (which i'm also using with no problems with my other T60)
I can heart a faint buzz from the speakers connected to the output.

Has anyone experienced anything similar?

thanks

[Chiana]

I have the dock as well on my T400 and have no buzz from the speakers. Do you have anything plugged into the audio jacks on the advanced dock?

[elthinkpado]

yeah, I have my amplifier and speakers.
but I had no buzzing from the T60.

yesterday I did a windows update and got the latest audio drivers for the T400
I haven't really checked well, but it gave me the impression that the buzzing from the speakers stopped after the installation of the new driver.

I'll check properly and post, it all might have been a problem with the drivers i was using.

[elthinkpado]

no luck.
I install the latest drivers provided by MS on windows update
and still buzzing.

I later downloaded the official drivers from the lenovo website. and still noise.

I changed the cable from the computer to the amp.
still the same.
(besides the T60 didnt do this)

The buzzing is quite low, and seems to come and go, it kind of an interference from the computer as sometimes when it loads it does it, some other times it doesnt, depending on what the computer is doing at the moment.

ideas?

[Harryc]

What happens if you plug the speakers/amp into the T400 undocked but plugged into the same outlet as the dock? Unplugged?

[elthinkpado]

I unplugged the amp from the dock audio out, and plugged it directly to the headphone out on the front of the T400
Seems to be no noise

any ideas?

PS:sorry for taking ages to respond.

[Harryc]

I am guessing there''s a ground loop at the outlet that the dock is plugged in to. Run a long extension cord to another outlet as a test.