[gooberdude]

I hope this is adequate for the lab.  If not, please move it to the appropriate circle.

A new tube preamp has been in the system a few weeks, hasn't given me any problems until i come home from work today and a kinda loud high frequency hum is audible thru my co-axs with no music playing.  Made sure all the connections were tight, reset everything but still it persisted.

Swapping the power cord with my amp's cord has solved the issue 100%.  The preamp did not have a grounded pc before.

Does this make sense, and if so why hasn't this been an issue the last 2-3 weeks.  I live in a downtown location, pretty heavy EMI/RFI.  At first i thought the tube had gone whacky.   

any assistance is appreciated.

matt

[max190]

Matt, this is a new preamp with a detachable PC?

[cheap-Jack]

Hi.

Swapping the power cord with my amp's cord has solved the issue 100%.  The preamp did not have a grounded pc before.Does this make sense, and if so why hasn't this been an issue the last 2-3 weeks.  I live in a downtown location, pretty heavy EMI/RFI.  At first i thought the tube had gone whacky.   

matt

Check up the PC socket of yr new pramp if it is a standard 2-pin or 3-pin there.

For EMI/RFI noisy areas, RFI noises can come & go!


c-J