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Krell KAS amplifier hum

The amps are directly plugged into their own dedicated 20A outlet.  Is there a "conditioner" I can use to minimize/eliminate the mechanical hum I'm hearing through my MBL 111f speakers.  I'm not looking for a multiple outlet item, rather, one which plugs directly into the wall and into the back of each monoblock.  Please advise and thank you in advance.

Best,
Jose
jg2077
jea48
4,449 posts
 
jg2077 OP47 posts

12-13-2019
11:43am


It would be easy to plug the 5.0 into one of the unused 20A outlet, as would be to move the Pre. Having to Move everything would require MUCH work. Could I use a long heavy-duty power cord plugged into one of the 20A outlet to power the 5.0 distributor where it sits without moving it?

How long is the heavy duty power cord?
25ft or less? If yes that would be fine. Just don’t coil up any excess cord.



jg2077 OP
159 posts
 
Update:

1.  All was left as initially, I only powered up the amp; very low hum from the speakers (ear against the speaker).  Could not be heard from 1 ft. away. 

2.  Unplugged pre from back of distributor and turned ON the distributor.  No change from above. 

3.  Plugged in Pre, the hum increased significantly. 

4.  Unplugged distributor from common 15A outlet.   Ran a 10ft cord from unused 20A dedicated outlet to the distributor  and powered on.  Same outcome as noted above; maybe...slightly less hum.

I will try another Pre and report back.   I have to take my son to pitching lessons. 😀

Regards, 
Jose 
jg2077 OP
159 posts
 
Update:

I replaced the 6L6 tube and left all else the same; the hum can only be heard from 18inches away, without any music. Also, the hum is of a lower frequency.   I can tolerate this for the time being. 

I am going to replace the ARC Ref3.  I haven't made up my mind as to my next preamp choice. 

Thank you all for helping. 

Happy Holidays, 
Jose
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