DC Offset Blocker/Killer - where to buy in the USA - for MC8207

TomIV

Member
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
 
I have never heard of there being any significant DC offset in the power out of the wall. Your electrician is probably right and whoever told you you need a DC Offset blocker is yanking your chain, especially considering you already tried a power conditioner that should be filtering the snot out of your power and outputting nothing but clean 60 cycle AC.
 
I was told that by Chuck Hinton who works for McIntosh who is a tech from what I know. I still haven't checked for dc in my ac line but after all I have done that is the only thing left to try, but why would I need to try that, why would I need to spend any more money to make their non working properly transformer silent or quieter. I feel like I am getting the run around. But I would like to give it a try if I can find one to buy here in the US.
 
I have similar DC issues. But here are 2 off the top of my head.

https://avahifi.com/collections/used-demo-and-quick-ship/products/humdinger-dc-line-blocker

humdinger-iec-side-800x600_480x480.jpg
 
I have never heard of there being any significant DC offset in the power out of the wall. Your electrician is probably right and whoever told you you need a DC Offset blocker is yanking your chain, especially considering you already tried a power conditioner that should be filtering the snot out of your power and outputting nothing but clean 60 cycle AC.

I even have it on dedicated ac lines. I use a Burmester 948 conditioner that can actually show you how much DC is present. Push the button and watch it disappear to noting. The sound of my system gets noticeably better engaged.
 
Hello TomIV

1) DC in AC power line do not exist because if it is the case the DC generator will be immediately destroyed by your AC line
2 ) I know the problem with toroidal power transformer only . This is coming from switching power supply really bad made, and do not garanty you to keep your AC line free from pollution
3) it is not necessary to buy something to "clean" your AC line
4) you can do it very easely with diodes and capacitors . The components necessary to build this depend of the maximum power consomption of your "singing" power transformer
the noise that you can hear is coming from the core of your toroidal power transformer which is saturate and can't work normaly
you have to see from where it is coming from. Most of case it is coming from bad quality switching power supply like power supply for lighting or separate switching power supply from small units sometime
5) do you have such separate switching power supply at you ?
 
Hello TomIV

1) DC in AC power line do not exist because if it is the case the DC generator will be immediately destroyed by your AC line
2 ) I know the problem with toroidal power transformer only . This is coming from switching power supply really bad made, and do not garanty you to keep your AC line free from pollution
3) it is not necessary to buy something to "clean" your AC line
4) you can do it very easely with diodes and capacitors . The components necessary to build this depend of the maximum power consomption of your "singing" power transformer
the noise that you can hear is coming from the core of your toroidal power transformer which is saturate and can't work normaly
you have to see from where it is coming from. Most of case it is coming from bad quality switching power supply like power supply for lighting or separate switching power supply from small units sometime
5) do you have such separate switching power supply at you ?

I do not have any of those items you described, the only things that i have in the house are 3-TV's, Fridge, Microwave, Dishwasher, Oven, couple of computers, phones and ipads, Dryer and Washing, Furnace, Boiler and Central AC, and a Sump Pump that has a second Back UP Pump and were all bought brand new when we moved in our home 5 years ago.
I also had a printer that worked on 220V so I had two 220V outlets installed but they don't seem to interfere with anything.
 
Can this symptom re-produce at the dealer?

When I returned it they were too busy to check it but I never heard back from them so I guess it did the same. Should I care if it reproduces the same sound at the dealer, I mean come on they run freaking $50K-$100K power re-generators, conditioners, transformers and whatnot probably they can hide the buzz but that is not the point, the point is why when spending this much money on this kind of equipment have a buzzing problem.

I already installed isolated 20 amp outlet with it's own grounding, neutral and power line. I bought power conditioner that cost as much as the amp to no help, and it did the same buzzing sound at my friends house. I am testing this amp in normal homes because as far as I know this amps are for the home consumer right?
 
If the linear power supply in a $400 receiver a $100 vintage receiver can handle your mains power, there is absolutely no reason that the supply in your megabuck McIntosh gear shouldn't. The fact that they couldn't be bothered to test it's functionality for you when you took it in is a huge red flag in my book.

The other reason I question the DC in the mains power theory is that your $4000 power conditioner most likely has a big ass toroidal transformer inside of it. Part of what most power conditioners do is use a big transformer to isolate the connected devices from noise on the mains. That transformer by definition does not pass DC.
 
But why does McIntosh insist that I check for DC in my Mains and buy a DC blocker, after I installed a 20 amp isolated outlet, why wouldn't they say and admit that there is a problem with this amp or the whole 8207 line.
 
Some amps are just more susceptible to the problem. Can you bring it to a neighbor and try it? I've tried other fancy conditioners and AC re-generators and the problem on some amps persisted. My McIntosh gear is dead quiet but some others vibrate.

My Burmester takes care of it nicely.
 
Some amps are just more susceptible to the problem. Can you bring it to a neighbor and try it? I've tried other fancy conditioners and AC re-generators and the problem on some amps persisted. My McIntosh gear is dead quiet but some others vibrate.

My Burmester takes care of it nicely.

I already did bring it to my friend and another friend and it does the same.
 
I already did bring it to my friend and another friend and it does the same.
Tom, that's unfortunate. However, your McIntosh dealer should be ready, willing, and able to help you sort this out. Your responsibility was to buy it, connect it, and listen to it - which you've done. You shouldn't have to carry an amp to multiple locations in an effort to troubleshoot a problem as this.

I've found the words I'd like a refund to be very powerful in convincing a reseller that they have a responsibility to me after I've made a purchase. Good luck.
 
Tom, that's unfortunate. However, your McIntosh dealer should be ready, willing, and able to help you sort this out. Your responsibility was to buy it, connect it, and listen to it - which you've done. You shouldn't have to carry an amp to multiple locations in an effort to troubleshoot a problem as this.

I've found the words I'd like a refund to be very powerful in convincing a reseller that they have a responsibility to me after I've made a purchase. Good luck.

The dealer was easy to work with to replace it and they want to replace it again to what I said I don't want another if it does the same I want to find a resolution to this problem, and if this is McIntosh's problem than they should admit to it and not blame it on my power, why my other equipment and appliances don't make any strange noises. I hate when a manufacturer tells me that I might have bad power when the problem could be in them. I am already few thousand dollars to make their problem go away but that's all it is masking a problem. I don't feel like I should be installing a DC Blocker or whatever the heck it is, all it's gonna do is mask the problem, what if the transformer is bad I would never know right?

I don't know man I am exhausted.
 
DID you try the amp when you picked it up from the dealer after the repair. I would have insisted on trying out the amp before taking it home. If it worked all right at the dealer OK. But if it didn't I would want a new amp!. At least remove the amp and plug it in some where else off the property and make sure. I know its a pain, but you have to do what you have to do. You have already spent to much money..
 
Back
Top Bottom