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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
4,486 posts
 
tomiiv30 OP21 posts01-05-2019 12:47pm


And this is what I get from the dealer:

"Ron from McIntosh says he might hear of this buzzing issue 5 times a year. It is an amp that is 14,000 watts so it is sensitive to DC being present in the lines. He said it has to either be the electrical coming from the pole or something within your house that is introducing DC in the AC of the lines ie. Faulty/poorly designed dimmer switch or something similar. So it is certainly not the amp or us, it is something going on at his specific home. It could be something as little as 1 volt of DC that can cause this issue."

Does this look like the McIntosh is siding with the dealer and not me, is it my f’ing problem that I spend over $20K on Mac product to be told that I am in the wrong.

It is an amp that is 14,000 watts so it is sensitive to DC being present in the lines.
I think you meant 1400 watts.



He said it has to either be the electrical coming from the pole or something within your house that is introducing DC in the AC of the lines ie. Faulty/poorly designed dimmer switch or something similar. So it is certainly not the amp or us, it is something going on at his specific home. It could be something as little as 1 volt of DC that can cause this issue."

No,.... there’s nothing wrong with the AC power in your home. You measured for DC offset on the AC mains using your DMM and measured 0.9mv. You measured for DC offset exactly as McIntosh told you to do it. Exactly!

tomiiv30 OP21 posts01-05-2019 10:40am


@jea48 When I called Chuck at McIntosh and told him my problem he said and these were his words" Get a multi meter and stick probes one into the neutral the other into the phase and measure for DC mV, and that’s what I did. I am not going to do anything more than what they suggested.
Chuck is the man, he should know. He is McIntosh’s expert on the subject. You followed his instructions to the letter. Can’t get any simpler than that.
There is nothing wrong with the AC power in your home. The power transformer in the amp is defective. Period!


.
erik_squires
16,290 posts
 
Agreed.

If you measure that little, you need to take the amp back and prove it there.

Best,
E
jea48
4,486 posts
 
erik_squires4,643 posts01-06-2019 11:54am


Agreed.

If you measure that little, you need to take the amp back and prove it there.

Best,
E

erik, keep this just between the two of us. Chuck is just plain ignorant when it comes to how to measure for DC offset on the AC mains.
Jim
erik_squires
16,290 posts
 
Balanced power conditioners also work.

But seriously, the best way to tell if this is a power issue or defective manufacturing is to take the amp somewhere else.

Best,
E
tomiiv30 OP
65 posts
 
After some serious thinking I will just return this unit for a full refund, I shouldn’t be the one obligated to do all those things since everything else works perfect in my house I know that I don’t have problem with my power and it has been checked so many times, I don’t have to invest anymore time and money in any kind of aftermarket equipment to silence the buzz, I would try with the DC blocker like the Emotiva CMX-2 that was shipped to me by a forum member but that’s that, it will just mask the problem and nothing else. Yes taking it to the dealer and having no buzz there means that they use all kinds of power conditioners and dc blockers and what not would not prove anything to me, this unit does not work at my place and at my friend’s, I have taken this unit to two others and still buzzed.
If McIntosh does not want to invest in a proper circuitry that will fix this problem that they are having and they do have this problem for a long time I can see that since there were many people on forums saying the same thing that I am saying and we as consumers should not be held accountable for it.
There are some threads that I red about the MC462 being dead on arrival which is another thing that tells me that quality check is lacking, since I am also having issues with loose parts on mine.
McIntosh you better get your sh$t together otherwise you would start losing some serious sales or maybe you already have.

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