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DC Offset Blocker/Killer - where to buy in the USA

   I have McIntosh MC8207, the first unit I bought from an authorized dealer came with a loud buzzing coming from the left transformer, and was replaced with a new unit which came with even a louder buzzing. The buzzing can be heard from 8 feet away. Then I was told to have install new 20 amp outlet that has its own isolated grounding.
   That was done professionally by an electrician who installed two isolated 20 amp outlets, two 20 amp circuit breakers, two copper polls for grounding for each outlet, each outlet has its own neutral and power line. After all this done the buzzing sound was still there.
   I was then told to buy a power conditioner which I did (Audio Quest Niagara) which was like $4000 and that did not help. Called back McIntosh and was told that I might have DC offset in my AC line and was told by McIntosh that I would need a DC Offset Blocker/Killer to which when I asked them where to buy one they told me to go on the internet and search to find one, to which I cannot find one.
  This bothers me a little bit, if you as a company think that I have dc in my ac and i need a dc blocker wouldn't you need to sell one as well. I brought this amp to my friends house and it was the same no improvement, so my guess is that he has dc in the ac line as well.
   So If anyone of you knows where to buy a DC Offset Blocker/killer please let me know, but even if this helps kill the buzzing wouldn't you guys think that this expensive somewhat hifi amp/brand should be silent from the factory. I mean this is two units in a row all purchased brand new.

My house is 5 years old, everything is brand new, the whole neighborhood is about 8-9 years old, my electrician says that I have perfect power coming to the house and everything looks fine.

Thank You

tomiiv30
jea48
4,439 posts
 
@ stereo5

As I said in an earlier post tomiiv30 needs to hire a Power Quality testing company to check the quality of the power in his home. Some electrical contractors may have the needed test equipment to preform the test, but most don’t. For many electrical contractors it is cheaper to hire a Power Quality company than buy the testing equipment. In my area a certified, qualified, power quality testing company charges about $125 an hour. A good single phase power quality analyzer can run around $10,000. And then you need a tech that is trained, certified, for its’ use. The tech will explain the problems, if any, and then recommend the solutions to solve the problem/s.

If the power quality problem/s is coming in on the electrical service entrance conductors the tech will provide the necessary, certified, print out test results for the customer to give to the utility power company.

Jim



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cleeds
5,951 posts
 
jea48
tomiiv30 needs to hire a Power Quality testing company to check the quality of the power in his home.
Agreed. And if the OP seeks a definitive assessment of the unit itself, he'll need to send it back to McIntosh or to an authorized service center for a complete evaluation. That's something his dealer - which he for some reason won't identify  - apparently isn't equipped to conduct. Simply plugging it in to see if it buzzes isn't the equivalent of a proper bench test.
twoleftears's avatar
twoleftears
5,318 posts
 

Agreed.

And furthermore: just because a unit doesn't hum (or whatever) in one location (be that the dealer's or elsewhere), it shouldn't hum in most domestic locations.  Humming there is an indication of either an imperfect design or a faulty unit.  Consumers should have a reasonable expectation of a unit working properly in their home, rather than manufacturers having an unreasonable expectation of utterly perfect electricity in every home.

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jea48
4,439 posts
 
cleeds1,989 posts02-08-2019 10:48am


Simply plugging it in to see if it buzzes isn’t the equivalent of a proper bench test.

Agree.

The AC mains voltage might be 115Vac - 117Vac at the wall outlet at the dealer’s store. The OP’s mains voltage might be 123Vac, maybe 124Vac. At the lower voltage the buzzing problem with the transformer may not show up.

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