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
Thanks for the explanation Erik.  So I have two issues to figure out...  I wonder what the odds are of the buzzing issue persisting if I upgrade to the Mac 462...  I’ll be demoing the 452 shortly so I will find out then.  If the buzzing continues i’llbe in the same boat as the OP....


Well,  If you find yourself in the same position as the OP, then demand a full refund, and find unit that does not have this problem. Been there, done that.
@ nyev



See page #17. It appears the power transformer is an EI type. EI type power transformers as a rule are not affected by DC offset on the AC mains

https://www.manualslib.com/manual/1460643/Mcintosh-Mc462.html?page=17#manual

Question is why would you still want to buy a McIntosh product after hearing the way they have treated the OP? Ron ( McIntosh representative) said maybe 5 complaints a year about torid buzzing power transformers. You want to beat the number of complaints is actually higher than 5?

How much would it have cost for McIntosh to incorporated a DC blocker in the MC8207 amp? I would be willing to bet the design engineer first designed the amp with a DC blocker. No doubt the design engineer new that a large torid power transformer would vibrate/buzz if there was DC offset on a customer’s AC mains.
How much you think them pretty covers cost that cover the transformer and DC power supply inside the MC8207? Or them big pretty blue front meters?
They sure look pretty though don’t they?

Charlie Randall (top USA dog now) is already starting to make ARC equipment look like McIntosh.

.
jea48
... why would you still want to buy a McIntosh product after hearing the way they have treated the OP?
Because we don’t know how McIntosh treated the OP - it’s just hearsay from an anonymous poster. On the other hand, I have years of first-hand experience with Mac.

Charlie Randall (top USA dog now) is already starting to make ARC equipment look like McIntosh
ARC doesn’t look at all like Mac - ARC has rack width; choice of silver or black finish; no blue meters or logo in a Gothic font ...

Would you guys be surprised if I told you nothing happen out of this situation. I get to keep this amp the way it is, it’s been over their return policy period and nobody cares to even take a look or find a solution to a problem that not just me but others are having and it is very common within McIntosh amps.
I can tell you that nobody gives a flying f$%k about the consumer anymore, they just want your money and that’s that. Once you pay you are alone and that’s how I feel.
The salesman could do just so much, he is there just like a middleman without having any authority over anything except to sell and make management happy. Even he admit it that this place sucks balls so what would you expect from place like that.
Learnt from my own mistakes but I ain’t getting screwed again after this kind of treatment that I got from Manufacturer and Dealer.

$30K in the hole and not one phone call to me. I was better treated when I bought a $200 item and was make sure I was happy with my purchase.