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

Discussion in 'McIntosh Audio' started by TomIV, Jan 2, 2019.

  1. joeinid

    joeinid AK Subscriber Subscriber

    Messages:
    909
    Location:
    NY
    Already done as of 12/1/18

    But the increases are relatively small. $500 on single items and $1K per pair of mono blocks.
     

     

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  2. sregor

    sregor AK Subscriber Subscriber

    Messages:
    3,648
    Location:
    Mass
    May not have any bearing, but one of my friends had a problem with a big SAE amp mechanical hum - turned out to be interaction with the steel table it was sitting on. About 1/2 inch spacing and problem went away. Another similar issue had to do with wavy lines on a CRT - problem was due to large (5 KVW) transformer on the other side of the wall....) My 2 cents
     
  3. TomIV

    TomIV Member

    Messages:
    78
    All the suggestions are very welcome, I appreciate everyone on this forum weather their comments are negative or positive, at the end it would help me and hopefully would help others as well.

    Knowing that this is a dealer that sells high end electronics one would think that their store is completely treated for this kinds of problems, they would not want to have a customer hear a buzz or any noise while they are demoing their equipment, am I not right.

    Right now I am going to relax because my head is spinning and it's about time I enjoy my stereo system and listen to some quality music.
     
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  4. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,275
    Location:
    France
    Hello TOM

    Went to the dealer today with the MC8207 and right away I was taken upstairs to their tech department where they plugged this amp and the result was a dead quite none buzzing transformer and I mean dead quite not even a small buzz.

    You see , your amplifier is perfect

    Now I don't know if their outlets have been treated since this is the tech department and not any other place in the store, it was the only place that we tested it.
    no , without to be there I can tell you that no , nothing has been treated

    I am a person that do not give up and would like to find a solution to fix this problem no matter what it takes as long as it is fixable.
    thank you for your honesty
    That's good news that you did not giving up !

    And if anyone from here ever had to deal with their electric company would you be kind to share the steps taken to convince them to come out.

    I will suggest you to build "my filter " (see the schematic I have posted many days ago) ! I honestly think that will clear your problem .

    build one here in France and ship to you in USA will cost you much more
    Ask somebody able to do it and you will see !
    Keep us informed
    Everybody is watching
     
  5. c_dk

    c_dk Addicted Member

    Messages:
    6,419
    Location:
    West Michigan
    Patrice,

    I have no idea what the situation is in France but here in the USA we have a very litigious society, lawyers are lurking around everywhere looking for cases to bring to court.

    So while any number of us could build either your or Rod Elliot's circuit I do not think anyone would really dare to get involved.

    In any case since my research shows that Philton, the transformer manufacturer, and Rod's posting dates from 2008 this issue has been known for a long time now.

    Have other manufacturers who use these very large toridal transformers built in solutions? You seem to state that this is a relatively common issue in France........beyond RonC's caviler condemnation of "cheap" light dimmers and hair dryers, what are the more continuous sources of these DC invaders? Are there industrial processes that will cause issues in the main supply trunks lines that you know of?

    I would hope that Mac's engineering team will step up to get to the bottom of this now known issue and offer some solutions to it's dealers and end users.
     
  6. joeinid

    joeinid AK Subscriber Subscriber

    Messages:
    909
    Location:
    NY
    I discovered my dc issues more than 10 years ago. I’ve never been able to discover the source. Some amps are/were worse than others. Between my current (no pun intended) power conditioner and some dc blockers, I’m under control enough to realize a wonderful sounding stereo. Amplifiers now, both McIntosh and others are quiet transformer-wise. I commend Tom for following through and trying to totally root out the problem.
     

     

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  7. TomIV

    TomIV Member

    Messages:
    78
    @c_dk
    @joeinid
    @clinic-audio

    just like c_dk said that this problem has been known for at least the last 10-12 years and I would like to hear it from McIntosh an explenation of why they have not came up with a solution yet, since they decided to use this kind of transformers, I think we the consumer should at least hear their opinion on the matter.
     
  8. EngineerNate

    EngineerNate AK Subscriber Subscriber

    Messages:
    3,467
    If such a simple DC blocking circuit as the one clinic posted were the solution, why is that circuit not built into the amp or alternatively built into one of the DC blocking/power conditioning devices Tom has tried.

    There may be nothing "wrong" with the amp. But it's certainly not a robust design if it needs the AC line of the gods to run quietly.

    I design things for a living. If one of my designs worked in the clean room in the lab but failed to function in the field, I'd get fired. Failing to engineer fault tolerance into the design is a problem even if the amp is working as intended.
     
  9. c_dk

    c_dk Addicted Member

    Messages:
    6,419
    Location:
    West Michigan
    I was just a rookie in 1978 but i do remember DOB speaking of the MC2205 and MC2200 relay issue that caused much concern with channel dropout that just seemed to be happening in the NYC area. Turns out the power company for the NYC metro area was purposely dropping the voltage causing the speaker relay to not fully latch. A service bulletin was finally issued, modifications were made to the circuit for production but ultimately who knew.

    Outstate NY is on a different grid much closer to the Niagara power station......but finally someone figured it out.

    Did I not just hear in the news that a federal judge has ordered PC&G to cut back on their power output during certain windy conditions to prevent wildfires, with possible brownouts to come back to California?
     
  10. damacman

    damacman Blown and Injected Subscriber

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    So, has the dealer scheduled a service call to your home in an effort to help you resolve?
     
  11. c_dk

    c_dk Addicted Member

    Messages:
    6,419
    Location:
    West Michigan
    I am sure the dealer is at wit's end not knowing what to do. It is really time for the factory engineering team to step up and offer more guidance than what tom is reporting.....that said a tech from the dealer should be on hand when the electrical contractor doe his more extensive tests......probably with the dealer picking up the tab.
     

     

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  12. TomIV

    TomIV Member

    Messages:
    78
    @damacman

    They wanted to charge me to come out to the house to diagnose the problem but when I asked them how they would do it I did not get a clear answer so nope they won't be coming to my house. I am keeping the amp as is because at the store was dead silent and that's that you can't argue any further, I was shut at that moment and it's back to my house. And if it's from the outside than it is out of my hands and it would be very hard to get ComEd to come out which is our electric company here in IL. to fix it, I have to talk to my electrician when he comes here as to what my options are or if he has somebody form ComEd that he works with to have them come out here.
    At least my stereo system works and is dead quite with no other anomalies.
     
  13. joeinid

    joeinid AK Subscriber Subscriber

    Messages:
    909
    Location:
    NY
    On one set of amp where I first discovered my dc problem, it took 2 dc blockers in series to make them dead silent.

    I was going to send Tom two that I had on hand, I wish now that I did to see if that would have temporarily or permanently fixed his issues.

    I only sent one to him and wish I had sent both. At least for a test to see the level of correction that he needs.
     
  14. TomIV

    TomIV Member

    Messages:
    78
    @joeinid

    Go ahead and send me the other one if you are not using it, I will test it out and see what happens.
     
  15. joeinid

    joeinid AK Subscriber Subscriber

    Messages:
    909
    Location:
    NY
    Great, I’ll box it tomorrow and drop it off Monday. Should have it Wednesday, no strings attached. Seriously, my curiosity is piqued as well.
     
  16. c_dk

    c_dk Addicted Member

    Messages:
    6,419
    Location:
    West Michigan
    Joe

    If you get a chance and can, pull the cover off the Emotive before you ship it and post a picture. Inquiring minds want to know to compare it's circuit to Rod's and Patrice's.

    I can not fathom the cockeyed idea that the dealer gets to earn his profit by just taking a order.......Mac's national sales manager should place a foot in the proper place.

    I am sure Mr. McIntosh and I know the Gordon Gow I knew are rolling in their graves.
     

     

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  17. joeinid

    joeinid AK Subscriber Subscriber

    Messages:
    909
    Location:
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    Ok, give me a little while. I’ll do it now.
     
  18. joeinid

    joeinid AK Subscriber Subscriber

    Messages:
    909
    Location:
    NY
    Hmmmm, not sure which screws will open it up and which will just loosen parts inside.
     
  19. joeinid

    joeinid AK Subscriber Subscriber

    Messages:
    909
    Location:
    NY
  20. joeinid

    joeinid AK Subscriber Subscriber

    Messages:
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    Location:
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