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Buzz, hum, graveyard

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Posted on December 25, 2020 at 09:18:17
AudioDwebe
Audiophile

Posts: 1908
Location: Pacific Northwest
Joined: November 12, 2001
Why do some of my amps cause buzz through the speakers, have their transformers hum or are dead quiet using the same damn system?

I've got a few amps and, for the life of me, can't figure out why it is one causes buzzing through the speakers and a few have the transformers humming along easily heard from the listening seat berween songs while others are dead quiet. This with no change to the rest of the system.

I think I've got ground loop or other issue with the electrical circuit in my music room as I've got a transport that also has a humming transformer in the room but in another room of the house it's quiet as it should be.

Is it the way the amps are designed that causes them to handle the juice in this room in a different manner?

It's a bit frustrating.




"Man, that mouse is Awesome." - Kaemon (referring to Jerry, of Tom and Jerry fame)

 

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Could be DC offset on your powerline..., posted on December 25, 2020 at 18:54:55
jbrrp1
Audiophile

Posts: 483
Location: Minnesota
Joined: April 24, 2007
Different transformers behave differently in the presence of DC offset, and it may just be that the affected equipment is susceptible. That's one hypothesis. if you have a good VOM meter, you could check for DC on the power feed. I've had troubles with that in my house from time to time, and I solved it by going to a PS Audio regenerator.

 

RE: Buzz, hum, graveyard, posted on December 26, 2020 at 06:19:00
mlsstl
Audiophile

Posts: 1072
Location: Midwest
Joined: September 1, 2015
You should also check all of your wall outlets in the room to see if they are correctly wired and grounded. You can get an outlet tester for as little as $5 or $10.

 

RE: Could be DC offset on your powerline..., posted on December 26, 2020 at 08:53:02
AudioDwebe
Audiophile

Posts: 1908
Location: Pacific Northwest
Joined: November 12, 2001
Are you saying to put the test leads into the wall outlet?

How do you check for DC offset?

Thanks.
"Man, that mouse is Awesome." - Kaemon (referring to Jerry, of Tom and Jerry fame)

 

RE: Buzz, hum, graveyard, posted on December 26, 2020 at 08:55:40
AudioDwebe
Audiophile

Posts: 1908
Location: Pacific Northwest
Joined: November 12, 2001
Thanks for the tip. I only checked the outlets my gear was plugged into.
"Man, that mouse is Awesome." - Kaemon (referring to Jerry, of Tom and Jerry fame)

 

RE: Buzz, hum, graveyard, posted on December 26, 2020 at 10:55:47
6bq5
Audiophile

Posts: 4363
Location: SF Bay
Joined: August 16, 2001
Notwithstanding the comments above/below-

Yes, the design/execution of the circuit can affect the amp's ability to generate hum-

There are lots of tricks used as the power comes into the unit - Thermistors, Caps, and Inductors -

But there is also the issue of how the transformer is made-
How tight is the stack (E-I)
The pack of the windings
Is it Varnished or Potted?, How?

And that is all added into the mix...
Quality of your Mains Power
Shields on Interconnects
How many circuits are you powering the system with-
What else is on you Mains Power - a variety of equipment can introduce noise or hash into the mains power - which can be exacerbated by design choices...
Not to mention orientation of equipment and transformers/inductors within the equipment -
Happy Listening

 

RE: Buzz, hum, graveyard, posted on December 26, 2020 at 11:09:10
I suspect there's trouble with his long runs of 'balanced' interconnects

it makes me suspicious that something is not actually 'balanced' in the signal chain ... just from the description of the set up and trouble shooting performed so far ...

solution? I've no clue

regards,

 

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