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

Showing 6 responses by twoleftears

Audio by Van Alstine make a relatively inexpensive but excellently built model.  They also have a generous return policy.  If McIntosh can't or won't help, it would be worth trying (if only to eliminate the possibility).
It's a story as old as the hills.

A company spends decades establishing a really good name.

A conglomerate swoops in and buys it up--and they're buying the name much more than the factory or the know-how.  They proceed to try and squeeze every last drop of profit out of it--and then they'll throw away the dry husk when they're done.

The attitude you've gotten--it's your problem, we really don't want to take it back (=we've already made our profit off of you)--is a classic demonstration of this.

@tomiiv30I

I went through something similar with an amp.  I tried dozens of fixes, from cheater plugs, extension cords, turning off all the breakers, different outlets, inexpensive filters, expensive filters, ground loop eliminators, DC blockser, power conditioners, power regenerators, isolation transformers, you name it.  Nothing worked.  Ultimately, sometimes it comes down to the electricity coming into your house and how it interacts with the component.  I hope you have an experienced electrician, because most don't measure/don't know how to measure/don't believe are important, the kind of things, to vanishing small levels, that can be causing the problem.  And if he does identify it, good luck getting your local electricity company to address it.

I'm also here to tell you that if you buy a similar priced amp from a different company, there's every likelihood that it won't hum.

As much as we like solving a problem once it's been identified, sometimes the expedient thing is the best route (i.e. I hope you haven't exhausted the store's return/refund policy).

Because the toroid isn't manufactured properly; probably not wound properly.  More than one example hums because whole batches probably made with sub-par QC.  It's all down to the sub-contracted company that M. buys their transformers from these days.  Evidently not the same QC, and probably not the same company, as in the old days.  Once you stumble over a product that hums regardless of whatever else you do to remedy it, the only thing to do is get rid and move on to a different (and hopefully better) manufacturer.  That's what I did.  The monoblocks I own now (admittedly not massive) are absolutely silent.
All the emphasis is on McIntosh's famous output transformers.  Little mention of the IE power transformer.  Search Audiogon for McIntosh + hum.  There are threads going back years.

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.