Posted by Dave sK (A) on March 18, 2003 at 18:07:43

Hi all,

I have a Reveille line stage that I recently assembled and its been checked out at Welborne's shop. It works just fine on their bench. I am unable to eliminate the low level hum when its in my system. The CD player is grounded and I added an external strap between the CD chassis and the AC line ground but it didn't do anything. All ground connections measure zero ohms on my DVM. There are no other sources hooked up. There was no hum with the previous preamp (AE-1)so I have a baselined system that was hum free.
Any suggestions would be appreciated.

Thanks,

Dave

• Re: help with Reveille line stage hum - Chris O 05:33:24 03/19/03 (1)
  In Reply to: help with Reveille line stage hum posted by Dave sK on March 18, 2003 at 18:07:43:

  Like Ron says, it is likely that this is a system ground loop. However, someting else to try is moving the unit to a slightly different location.

  Because the Reveille has a input transformer it may be more likely to pick up a bit of radiated hum from a power amp transformer in close proximity. Try moving the preamp to a different shelf or position. Sometimes moving a component only an inch or two is enough to get it out of the field.

  My old AE-3 radiated enough EMI to hum my phono preamp from 6 inches. 7 inches was dead quiet.
  
  

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  • Re: help with Reveille line stage hum - Dave sK 06:09:29 03/19/03 (0)
    In Reply to: Re: help with Reveille line stage hum posted by Chris O on March 19, 2003 at 05:33:24:

    It was a ground problem. It went away after experimenting with different grounding points on the CD player. I had it down to residual that could only be heard with my ear against the speaker (not my normal listening position). I then was able to remove the residual by changing interconnects between the pre and amp. Looks like 4.5' Kimber PJB's don't have enough shielding for the environment. I'll need to make up a pair with a different wire - something with a full shield. By the way the MQ-100 main amps don't have an AC ground. Adding one really made things hum.

    Thanks for the suggestions.

    Dave
    
    

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• Re: help with Reveille line stage hum - Ron W 20:16:04 03/18/03 (0)
  In Reply to: help with Reveille line stage hum posted by Dave sK on March 18, 2003 at 18:07:43:

  Try lifting the ac ground of your amplifier.

  Ron
  
  

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