Ok, so from reading all this and assuming that everyone did the best that they could, I would be wary of buying a Mac unit, period. All the other equipment he owns has no trouble, but this unit, and even another replacement unit does.
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
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
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- 225 posts total
Try adding large paper/oil caps in series with one of the AC line wires, the type used for running AC motors and compressors, to see if it removes the hum. If does not resolve the problem the toroid could have enough of a magnetic field to excite some nearby ferrous object. Most likely the extremely toroid has shaken loose in shipping and/or is misaligned. Check the center mounting bolt for torque. If it really is a DC issue, then you could look up some ultraisolation transformer. I doubt you are using much the 5KVA of the transformer. Check the efficiency rating of your speaker and measure SPL one meter from your speakers and estimate how much power you are actually using. You can also plug in a Killawatt meter from Home Depot and measure power draw. This will help find a rating for an isolation transformer. As the problem appears with no output very little power is used. 90 dB SPL average is more than my ears can tolerate and with 90dB 1W speakers very little average power is actually used. 20 dB peaks will be at 100W. Most of the music energy is in the bass, where powered sub does the heavy lifting. Low frequency sounds are mostly non-directional and are mixed to mono on vinyl. So the need for stereo at low frequency is just not there, minimizing large speaker requirements, if you have a sub. This could lead to improved domestic happiness and possibly more flexible speaker placement. |
clearthink607 posts01-24-2019 10:50am The unit IS NOT defective, When the OP took the amp to the dealer it was taken to the service department. There it was plugged in, turned on, and the torid transformer did not buzz/vibrate. The OP said the torid transformer was quiet. The OP was in the room during the test. Again, the torid DID NOT buzz/vibrate. It was quiet. So what good would it do to send the amp back to the factory? The amp is not defective. It works as it was built to function. If the consumer has DC offset on his AC mains the torid transformer will buzz/vibrate. The more DC on the mains the louder the buzz. Should the manufacturer have incorporated a DC blocker on the line side of the torid transformer? Yes. But the manufacturer chose to save a few bucks. Ron, a McIntosh representative, said they get maybe 5 complaints a year about mechanically buzzing torids. His advice to fix the CUSTOMER’S PROBLEM is to buy a DC blocker. Probably most manufactures that use fairly large torid transformers, in their equipment, install a DC blocker. McIntosh does not. . |
- 225 posts total