2. amps-preamps
  3. 188545-177823

A persistent hummmm...

I have a Zesto Bia 120 all tube, Class A amplifier. I am currently using it with a pair of Volti Razz speakers - pretty efficient horn speakers. My problem is a hum that is audible from the listening chair. Most music masks the sound, but in the quieter passages, there it is. It hums the same way when nothing else is connected to it - just amp to speakers, or when the preamp is hooked up. I have had an electrician out to the house to check the ground. It was good, but he put two more 8 ft. copper bars in the earth - no difference. I had sent it out to George Counnas, the designer/owner of Zesto. He checked it out (and upgraded it while it was there). He couldn't make it hum. 

I have tried using an extension cord to other power outlets in the house, and the hum was no different. I have changed speaker wire in case my regular wire (no shielding or conventional insulation) was acting like an antenna. I have used a iFi DC filter. Obviously, I have changed over the tubes (KT88's). I use a PS Audio Power Regenerator, and it hums less when the amp is plugged into that device than when it is plugged directly into the wall.

 

When I use a high powered Class D amp, I do not get hum. When I use an old Scott 299A all-tube integrated, I do. That makes me think something is making the transformers hum, and the Class D doesn't have them in the same way.  

 

I remember reading that Michael Fremer had a persistent hum with his gear, and finally changed out a lot of his house electrical set up. My two electricians can't see a problem, but clearly, there is one. Anyone have any suggestions for other things I could try?

 

I live in the Boston area of Massachusetts - does anyone know electricians or audio experts who specializes in these kinds of problems? 

 

Thanks,

 

David

dtorc

Showing 1 response by andym23456

andym23456
11 posts
 

I recently experienced a slight hum and a slight intermittent bacon popping sound from my recently rebuilt Adcom GFA-565’s into my Polk SDA SRS 1.2tl’s.

Turns out that I’d also placed a Bluesound Vault 2i in the room, which connects to my network downstairs via a Ethernet over Powerline adapter.

First thinking it was my closet florescent ballasts, I changed to LED.  Partial problem solved. No more popping when the closet light was turned on or off.

Took everything out of all wall outlets one at a time. When I got to the Netgear Powerline adapter my hum and pops went away.

Now I  have to figure out an Ethernet run through the walls to go directly to the Bluesound Vault.

induced my own problem. But problem solved. Good luck with yours.

 

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