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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
tomiiv30 OP
65 posts
 
@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. 

I would try the other methods too but I feel like I have done everything they told me to do or was told to do, and I don't feel comfortable to spend any more time and money on this matter. I have other equipment in the house that does not buzz, hum or make any sounds out of the ordinary. I think that their amp is poorly design and that they should be the ones making sure this amps are not buzzing by maybe installing their own DC blocker/killer or whatever you want to call it in their amps so none of us consumers would have to deal with this what I am dealing right now. Not many have my patients.

Also I have turned off all the breakers except the one for the whole house and the one for the outlet where the amp is plugged into, the buzz was still there and you could still hear it 6-8 feet.


erik_squires
16,884 posts
 
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.

That’s pretty smart. :)

I never thought of that, as I was worried about the meter being damaged, but reading around the net it seems safe to do with a digital, and with a mechanical, just set it to the highest range first, then come down.

Glad you tried turning everything off.

One other thing you could do, is try moving your amp to another phase. Usually the circuits breakers alternate phase going down.  So if your amp is now on the top breaker, try the second fourth or sixth down.
jetter
3,117 posts
 
You have been great, but now its time to take it back.  If it hums at the store take your refund and look for another unit.  I am assuming the problem is not your electricity and that you have run another unit in the past without the hum.  Sorry, don't want to reread all.
tomiiv30 OP
65 posts
 
@erik_squires I tried every possible combination and nothing worked. The only thing left to do is wait for my DC blocker which a member of another forum shipped it to me and it is the Emotiva CMX-2 to come in and see if that will help and even if it does I would still be not satisfied with this amp, it should hum/buzz at all.
tomiiv30 OP
65 posts
 
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.
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