2. misc-audio
  3. 181882-152262

Weirdly Specific HUM issue

I have a pair of KEF LS50 Meta's driven by (2) Schiit Audio Lidar amps configured as monoblocks, coming through a Schiit Freya+ preamp. I use an Ompower EM1100 conditioner and Audioquest shielded power and interconnect cables.

I get a slight but noticeable hum in the Left speaker only (farthest from the preamp), but ONLY under these conditions:

Plugged into (powered on) power amp only (no source connection) - NO HUM
Preamp connected (balanced XLR) and powered ON - HUM
Preamp connected (balanced XLR) and powered OFF - HUM persists
Hum only stops when I physically disconnect the input from the preamp (same with both preamp output channels)
Thoughts? Why would the hum persist even with the preamp powered down?

Thanks in advance.

gwilmot

Showing 1 response by gwilmot

gwilmot OP
6 posts
 

Thanks for the replies - I forgot to mention I am testing with no inputs currently connected to the preamp. Also, the monos are not plugged into the same receptacle (in fact the right channel is disconnected completely).

 

I do have an iPurifier plugged into the same receptacle as the power amp, I’ll try switching it to the preamp receptacle.

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