McIntosh Transformer causing noise in speakers while disconnected.

[Doodski]

Exciting this.

It's just a matter of trying to find the source. Mix more speakers into the whole thing and experiment with them. Preferably one more amp. Experiment with different combinations. Move the stuff around physically and see what happens, change rooms, change houses and test. All to see when the phenomenon occurs.

See if you can record how loud it sounds and at what frequency or frequencies the phenomenon occurs.

I admire your science minded enthusiasm although there is pure applied science at play here and it is all provable stuff.
As per post #187 of this thread the solution is not to create more facts & more ideas but to solve what is before us.

 

[DanielT]

Okay. I hadn't read the whole thread. Just got curious about the phenomenon. The reason for it arose.

For another thread, a theoretically knowledgeable person is welcome to explain the phenomenon in general. Then describe the energy required to make an object move with frequency X at distance Y. That then of course, without a dedicated transmitter-receiver for the purpose.

 

[Doodski]

For another thread, a theoretically knowledgeable person is welcome to explain the phenomenon in general. Then describe the energy required to make an object move with frequency X at distance Y.

If you want action you must provide information, link the location, ask the question(s), detail the attempts to Google the information and make it easy for the experts to assist.

 

[Golf]

If it's audible on the centre speaker drivers, it's measureable.

That is sort of a nifty approach.

Even before during this thread I had the impression that high quality speaker sets should really have something like an OBD port, like cars, as for On-Board Diagnostic

 

[mhardy6647]

I admire your science minded enthusiasm although there is pure applied science at play here and it is all provable stuff.
As per post #187 of this thread the solution is not to create more facts & more ideas but to solve what is before us.

The difference between scientists and normal people...

The Difference

xkcd.com

Spoiler

(I have a signed copy in my hifi room -- I would)

Meanwhile, I'm hoping that @ClassG33, the OP, instead of moving loudspeakers around -- or posting to this thread -- is listening to on hold Muzak while he waits for Mac's tech support! Actually, I hope he's talking to them. I guess it's a little early in Binghamton, though.

 

[mhardy6647]

Please do not do that. I am embarrassed at some things in this thread. sigh* LoL.

Right-o. Both @Doodski and I would need to practice a little revisionist history first. Nobody needs to see me trying to teach myself how to use Audacity's "analytical" tools in real time.

I have just about talked myself into getting a copy of REW, though.
Now I am wondering how I could use the calibrated mic I have rather than buying another one -- given that it needs phantom power.

 

[JayGilb]

Buy a new stereo cabinet that has a bottom shelf wide enough to fit the McIntosh. In the mean time use a metal baking sheet and place it between the McIntosh and speakers to see if it interferes with the magnetic flux lines that is causing your problem.

 

[mhardy6647]

Buy a new stereo cabinet that has a bottom shelf wide enough to fit the McIntosh. In the mean time use a metal baking sheet and place it between the McIntosh and speakers to see if it interferes with the magnetic flux lines that is causing your problem.

For $1400, I am pretty sure McIntosh will sell him a black and stainless baking pan with McIntosh silkscreening, LED illumination, and a VFD status monitor.


After all, they stock these...

LB200 Light Box

Removable rear panel provides access to a large storage compartment where you can place unsightly components to declutter and beautify your home audio system.

shop.mcintoshlabs.com

The back of the LB200 is what makes it very unique. A removable panel provides access to a large 16.1" (41cm) wide x 4.4" (11.25cm) tall x 13.4" (34.2cm) deep storage compartment inside the LB200 where unattractive components can be placed to both declutter and beautify your home entertainment system.

Not unique. Very unique. That costs extra.

 

[mhardy6647]

Of course, the irony (no pun intended) of the @ClassG33's problem, referencing @restorer-john's work, is that (as I understand it) minimizing stray flux is one of the nominal advantages of a toroidal transformer. If so -- imagine how it'd be with a traditional E-I core power transformer!
Of course, this amp with the additional weight of a traditional PT definitely would be too much for that equipment shelf!

 

[tmtomh]

What you'll need:

• Decent size vertically mounted toroidal transformer with attached power supply, preferably CT split rail (not nnecessary but I wanted a rectifier, duals caps etc). I had a Definitive Technologies subwoofer I bought for parts with such a bracket. Still on the plate amp.

View attachment 358037

• A random centre speaker, but decent. The OP's is an expensive B&W. (Preferably with a reasonable crossover, particularly for the bass/mids/treble- this is an important clue)

View attachment 358038

View attachment 358039

• A DMM and a couple of leads. (that is not a reading BTW)

View attachment 358040

• A random woofer inductor and a few random electrolytic/film caps maybe

View attachment 358041

• Optional: audio analyzer to look at the spectrum.

Basically, we have inductive coupling from the giant McIntosh toroidal to inductors in the loudspeaker crossovers, which will be 2nd order networks or higher. The other thing with expensive speakers, is they of contain large and high quality inductors of all different values in various configurations. Plenty end up across the drivers themselves or in series with resistors in parallel configs.

I'd say the McIntosh toroidal is mounted with it's internal bracket mounting-bolt facing horizontally to the left of the amplifier. The random toroidal I have here is only about a ~300W unit and virtually unloaded, so the huge McIntosh, idling 5 channels and all the other circuitry will have a much greater effect at a greater distance.

I can't make videos/recordings with sound right now as we have gale force winds drowning out my 'hum' (and making me really angry), but it's quite audible in the centre speaker with a small woofer inductor acting as a pickup coil at 7" away from the barely loaded transformer.

I'll get a few recordings when this wind dies down.

Wow, amazing work John! Thanks - this is fascinating.

Dumb question: Since the vertical mounting of the toroidal seems to be of some relevance here - yes? - does that mean that it's worth @ClassG33 trying an experiment where he does not move the Mac and the speaker farther away from each other but instead just turns the Mac on its side? (Of course it wouldn't be practical to keep it on its side and use it that way - just an experiement.)

 

[anotherhobby]

Wow, amazing work John! Thanks - this is fascinating.

Dumb question: Since the vertical mounting of the toroidal seems to be of some relevance here - yes? - does that mean that it's worth @ClassG33 trying an experiment where he does not move the Mac and the speaker farther away from each other but instead just turns the Mac on its side? (Of course it wouldn't be practical to keep it on its side and use it that way - just an experiement.)

I think you'd need to tip the Mac up on it's face plate or back on it's binding posts to get the toroidal oriented the way you'd want.

 

[tmtomh]

I think you'd need to tip the Mac up on it's face plate or back on it's binding posts to get the toroidal oriented the way you'd want.

Ah, I see. thanks!

 

[DonH56]

What you'll need:

• Decent size vertically mounted toroidal transformer with attached power supply, preferably CT split rail (not nnecessary but I wanted a rectifier, duals caps etc). I had a Definitive Technologies subwoofer I bought for parts with such a bracket. Still on the plate amp.

View attachment 358037

• A random centre speaker, but decent. The OP's is an expensive B&W. (Preferably with a reasonable crossover, particularly for the bass/mids/treble- this is an important clue)

View attachment 358038

View attachment 358039

• A DMM and a couple of leads. (that is not a reading BTW)

View attachment 358040

• A random woofer inductor and a few random electrolytic/film caps maybe

View attachment 358041

• Optional: audio analyzer to look at the spectrum.

Basically, we have inductive coupling from the giant McIntosh toroidal to inductors in the loudspeaker crossovers, which will be 2nd order networks or higher. The other thing with expensive speakers, is they of contain large and high quality inductors of all different values in various configurations. Plenty end up across the drivers themselves or in series with resistors in parallel configs.

I'd say the McIntosh toroidal is mounted with it's internal bracket mounting-bolt facing horizontally to the left of the amplifier. The random toroidal I have here is only about a ~300W unit and virtually unloaded, so the huge McIntosh, idling 5 channels and all the other circuitry will have a much greater effect at a greater distance.

I can't make videos/recordings with sound right now as we have gale force winds drowning out my 'hum' (and making me really angry), but it's quite audible in the centre speaker with a small woofer inductor acting as a pickup coil at 7" away from the barely loaded transformer.

I'll get a few recordings when this wind dies down.

Good work, John. I think mounting the toroidal transformer vertically is key, so the radiated field is to the sides instead of up and down as it would be when mounted horizontally. Someone forgot basic EM theory and radiation patterns.

 

[mhardy6647]

Good work, John. I think mounting the toroidal transformer vertically is key, so the radiated field is to the sides instead of up and down as it would be when mounted horizontally. Someone forgot basic EM theory and radiation patterns.

Not to defend McIntosh -- but they probably never expected one of these amps to be in such close quarters with an abutting loudspeaker.

 

[ClassG33]

Interesting evaluation and charts. Hope that classG33 solved the noise issue by putting the McIntosh in a fair distance to the loudspeakers. It is known that the magnetic field from the mains transformer can be picked up by nearby speaker chassis. I had this at an Fender Combo guitar amplifier. In order to know what happens

In full disclosure -- because I think the phenomenon that precipitated this thread is very interesting -- I posted the basic question Somewhere Else (Polk forums -- again, I am all about disclosure ).
One of the stalwarts there offered a great suggestion in terms of understanding the phenomenon better (even though it won't really help @ClassG33 much if he's devoted to the B&W loudspeaker suite): If another kind (!) of loudspeaker is available in the house -- does another loudspeaker manifest the same effect or is it specific to the B&W -- maybe even to just the B&W center channel loudspeaker?

I do realize that not everyone runs a shelter for wayward loudspeakers as do, ahem... umm... I.
Still seemed worth puttin' out there.

I have Active HS8 studio monitors. I'll try that tonight. Can you run it by them whether the variable of a powered speaker with an internal amp would throw off the scientific method?

 

[ClassG33]

Inductive coupling, if that is what it is, will have resonant frequency(-ies) based on the inductors and capacitors of the two systems (amp and speaker).

The question is why is the McIntosh emitting so much. Maybe it's because there's no load? Maybe something is loose inside that's not grounding? Maybe something else is wrong.

Really appreciate your input and suggestion. Even when there is a load (that is, when speakers are connected and content is playing), it can still be audible between audio. I've played music in stereo and can still hear it thru the center, I've played it in surround, and the buzz is there when sound is playing thru it, which of course has to be very quiet audio in order not to mask the buzz. but I don't know if there is a human way to know if the sound is there when there is a significant load, i.e. higher volume. But it's always there.

 

[ClassG33]

This particular issue is arising in a 100% valve-free context. Pencil tapping's a great diagnostic tool (I usually use a chopstick ) but probably not gonna add much value here.

@ClassG33, another suggestion (very tangential to the topic of this thread but well worth passing along) from the Polk folk -- this isn't meant to be critical, but that equipment stand looks a bit insubstantial for that big momma amplifier. How much does the amp weigh and how sturdy is that "lowboy" shelf?
I will - humbly and with the best of intentions - suggest that you put that amp on a sturdy stand close to the floor.

True, I have a salamander archetype on the way. But it fits the cabinet and the supports double the existing weight. Haha I know, but it's temporary

 

[ClassG33]

In regards to the proximity of the amp to a speaker, like @OldHvyMec, I have a SS Mac amp (MC2205, 200 wpc, 85lb) about 3" from an L100. Zero issue with induced noise on the speaker. Though I've never tried it without the speakers hooked up.

I'm sure McIntosh service will be very happy to help the OP and resolve the problem.

That's a great comparison, thank you! It happens with or without any connection. The only variable change is proximity to the amp.

 

[ClassG33]

News to me. Can I assume that the Mac is powered up? How close is close?

I have measured as far as three feet from the Power supply side (R). However, the Transformer side (L) is the side with the most significant noise creation. In other words, the Speakers to the left pick up the noise considerably louder than speakers on the right, at equal distance.

 

[ClassG33]

I haven't read all the pages of posts but I can say 1) that amp shouldn't be turned on without speakers connected to it 2) the amp probably needs to be serviced. If its generating enough magnetic noise to be picked up by a speaker driver it's probably not healthy for you to be near it.

As @GXAlan replied earlier, I discovered this while I was troubleshooting the noise, isolating each variable one by one. I had the center disconnected, then powered the amp on with only the left and right speakers connected to test them with the center's designated interconnect - that is when I noticed it was still making a noise even while disconnected. So I never had it powered on without speakers connected until I had already discovered this.