McIntosh Transformer causing noise in speakers while disconnected.

[Golf]

@ClassG33: What frequency is the local power, coming from your wall mains? 50 Hz or 60 Hz?

 

[ClassG33]

@ClassG33: What frequency is the local power, coming from your wall mains? 50 Hz or 60 Hz?

I would assume 60, it being U.S. or is that not definite? I have audio engineering knowledge, but not much electrical knowledge.

 

[Doodski]

I appreciate the certainty. I could imagine this being a typical thing, it being such a high powered amp, but something did not sit right with me about it. Your assessment was amazing to read haha I did not expect such in depth answers, I am going to have to stay with ASR this is most impressive.

@Zapper is a working electronics design engineer with vast experience from what I am aware of. It is very fortunate for ASR that we may attract peeps with such a broad wealth of fundamentals and principles knowledge. I am acquiring all sorts of tidbits, details, terminology with new theories that I will use to expand and broaden my knowledge base. The recent RF theories stuff is a perfect example of me having holes in my RF theory understanding and I can now progress into subject matter never before realized. So we all are learning here @ClassG33. This thread has been a real treat for me.

 

[ClassG33]

@Zapper is a working electronics design engineer with vast experience from what I am aware of. It is very fortunate for ASR that we may attract peeps with such a broad wealth of fundamentals and principles knowledge. I am acquiring all sorts of tidbits, details, terminology with new theories that I will use to expand and broaden my knowledge base. The recent RF theories stuff is a perfect example of me having holes in my RF theory understanding and I can now progress into subject matter never before realized. So we all are learning here @ClassG33. This thread has been a real treat for me.

Glad to hear it's been a treat!! You 100% led this thread and helped it catch the fire of all the great contributions. Your assessments were well thought out and provocative, brilliant stuff for real. I really appreciate it all!!

 

[Doodski]

Glad to hear it's been a treat!! You 100% led this thread and helped it catch the fire of all the great contributions. Your assessments were well thought out and provocative, brilliant stuff for real. I really appreciate it all!!

Yeah it was a big blast rehashing those principles of electron flow but @Zapper really changed the entire premise of what is occurring when he made comment about the energy transfer requirements... LoL. I need to re-evaluate all my ideas.

 

[Golf]

Guess I would do one final test: Moving the two suspects, amp and center speaker, to a different location. Another room, maybe even another house. If I could reproduce the phenomenon there, I would no longer hesitate to contact McIntosh. (Maybe B&W too.)

 

[Doodski]

Guess I would do one final test: Moving the two suspects, amp and center speaker, to a different location. Another room, maybe even another house. If I could reproduce the phenomenon there, I would no longer hesitate to contact McIntosh. (Maybe B&W too.)

I think that is not required.
The theory(s) is sound, the test method is solid, the fault is clearly defined, the effect is obvious and even more importantly it is repeatable.

 

[Zapper]

I agree this is totally bizarre and I've never heard of this before.

Possibly dumb question from a rank amateur: if the Mac amp has such an enormous toroidal transformer, and the amp itself seems to make a low-level noise when on (albeit one the OP has to listen closely to hear), is there any possibility that the amp is emitting a powerful EM field because dirty AC (aka DC in the AC line) is saturating the toroidal and the sheer size of the toroidal is generating a field sufficient to excite those speaker drivers?

If that's at all plausible - which it might not be! - then a DC blocker could test the theory and possible eliminate the symptoms, even if it would not solve the root cause.

I was thinking about this possibility too. It's a plausible hypothesis that could be tested.

@Zapper said that there must be a very high frequency fundamental for the power transfer to occur across the air gap.

I don't want to overstate my level of certainty. I put out a hypothesis that I think best explains the observations. But I could be wrong! A hypothesis only value is it gives you something to test. I'm not sure how to test this one without test equipment though. Any ideas?

 

[mhardy6647]

How would one go about reaching out to them specifically?

Short answer -- I don't know.
Better answer -- nose around at the McIntosh forum at AK. They do seem to be, as I mentioned earlier, well connected.

This being said, and as mentioned by @Golf overnight (Eastern time) Mac is justly renowned for their service and support. One could do far worse than to call the company directly in Binghamton, NY and ask for service support.
EDIT: It was @radix that made the comment I misattributed to @Golf. My apologies to both!

Somebody asked about the OP's power supply. I am pretty sure he (they) are in the US and it's 60 Hz -- but not 100% sure.
OK, I am: https://www.audiosciencereview.com/...while-disconnected.53114/page-10#post-1920590 Thanks @ClassG33!
Yes, all (AFAIK) of, at the least, the continental US domestic (household) power is 60 Hz.

I think the sample is not from a absolute peak of the distorted sinusoidal waveform and are taken from a very distorted section and as result the proportions of the fundamental frequency versus the odd and even order harmonics are not as they would be with a non-distorted sinusoidal waveform. Maybe try a clean pure 60 Hz sine wave and then compare that to your FT analysis image here<?>

I did do that @Doodski

McIntosh Transformer causing noise in speakers while disconnected.

THAT sounds like good old power supply hum being induced into and detected or just transduced by the driver voicecoils.

www.audiosciencereview.com

OK, gang Some other thoughts (a bit scattered and perhaps even tangential, but not entirely pointless!).
As @Doodski and I have - ahem - hinted broadly with our comments about speakers and phono cartridges picking up radio signals , the fundamental (no pun intended) issue here seems to be RFI. RFI takes two -- a transmitter and a receiver. The transmitter, of course, is something in or about the amplifier.

The receiver is @ClassG33's B&W center channel loudspeaker. Since it is a "multi-way" loudspeaker -- it contains a crossover. I wonder if components in the crossover are the true bad actors in terms of picking up the "signal" from the amp? Not that this changes anything symptomatically, but perhaps it is unique to this combination of loudspeaker and that Mac amp? I'm just musing, mind you.

Grumpy old man aside: In the old days, the US FCC put the onus on the RFI emitter (e.g., a ham radio operator) to control RFI in response to complaints from the "interfees" [EDIT] those with receivers suffering interference. Nowadays many consumer products have a disclaimer about being potential sources of RFI. There are, of course, ways to control RFI impact on "receivers" (shielding, traps, physical location with respect to the source of interference). The same, of course, remedies could be applied to the "transmitter", too -- but the modern model seems to be to inform the end user that "interference comes with the territory, deal with it".

I think that's all I've got for the moment -- still waitin' for the coffee to kick in!

This is a fascinating challenge -- at least from the perspective of a just-savvy-enough-to-be-dangerous participant like me!
I feel like we're on rounds in a teaching hospital.

 

[Zapper]

I restricted it to the clean channel so I have enough samples (doesn't work with too few) :



View attachment 357823

Hmm. That shows a null at 60Hz.

 

[mhardy6647]

Guess I would do one final test: Moving the two suspects, amp and center speaker, to a different location. Another room, maybe even another house. If I could reproduce the phenomenon there, I would no longer hesitate to contact McIntosh. (Maybe B&W too.)

THis would control for the specific circuit in the house wiring -- which would be (could be) useful information.
We assume all electrical wiring is done correctly. That assumption's not always valid, though.

 

[Golf]

This being said, and as mentioned by@Golf overnight (Eastern time) Mac is justly renowned for their service and support.

No, that wasn’t me I believe.

 

[Doodski]

I was thinking about this possibility too. It's a plausible hypothesis that could be tested.

I don't want to overstate my level of certainty. I put out a hypothesis that I think best explains the observations. But I could be wrong! A hypothesis only value is it gives you something to test. I'm not sure how to test this one without test equipment though. Any ideas?

Introduce more RF energy into the energy power transfer path from the McIntosh to the speaker(s) and see if the waveform changes @ the transducer(s)?
That would require a RF energy source like a radio transmitter with variable frequency output.
Alternatively a RF detection circuit a la' a multi band radio might pickup whatever is coming out of the McIntosh.

 

[Golf]

I think that is not required.

If I was the McIntosh person confronted with this case, that would probably be my first inquiry: »Are you sure that neither your room nor your house is causing this problem?«

 

[Doodski]

I think that's all I've got for the moment -- still waitin' for the coffee to kick in!

I still go to Starbucks daily for my vente dark roast 3 cream 4 sugar but otherwise I am now using caffeine extra strength tablets through the day to maintain alertness and prevent dozing. It works well.

 

[Zapper]

As @Doodski and I have - ahem - hinted broadly with our comments about speakers and phono cartridges picking up radio signals , the fundamental (no pun intended) issue here seems to be RFI. RFI takes two -- a transmitter and a receiver. The transmitter, of course, is something in or about the amplifier.

You can read my dissertation on the topic back at #144 if you're so inclined. Get a mug of coffee first!

 

[Doodski]

You can read my dissertation on the topic back at #142 if you're so inclined. Get a mug of coffee first!

It seems your #142 link is corrupted.

 

[Zapper]

It seems your #142 link is corrupted.

Thanks. Could you refresh the page and try it again?

 

[Doodski]

Thanks. Could you refresh the page and try it again?

The link that you provided works properly now although it is actually post #144 and not #142.

 

[Sokel]

If someone wants to narrow it at a specific point in the video let me know.