McIntosh Transformer causing noise in speakers while disconnected.

[ClassG33]

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

The videos show me moving the speaker toward the amp and away from it. I have tested this at greater distance than in the video, however.

 

[ClassG33]

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.

I will try the baking sheet tonight and report back.

 

[ClassG33]

I will try the baking sheet tonight and report back.

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.

I do have a dedicated stand for the amp on the way, by the way. It will be in the same spot, and the cabinet will be slid over to the left.

 

[ClassG33]

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

I disagree. Go into any Magnolia and you'll find mono blocks exposed less than a foot away from 800 Diamonds, or Martin Logan Expressions on a 462 stereo amp.

**Edit
I agree about not expecting it to be side by side (kind of) The long term plan was never to have it stay side by side - always had the plan to move the cabinet over, once I receive the Salamander Archetype stand.

**Another Edit with screenshot:
The McIntosh Manual describes proximity to other objects, with regard to proper ventilation. It advises clearances of "2 inches [...] so airflow is not instructed.

 

[Golf]

So a conclusion so far could probably be like this:

• As @restorer-john demonstrated: The presence of some portly transformer, if powered, can very well make nearby passive and crossover network equipped loudspeaker sets hum/buzz, even if they are not cable-connected.

• Questions on the above:
– What can an amp’s developer be asked for in order to avoid this?
– What can a speaker sets’ developer be asked for in order to avoid this?
– What can a respective customer/owner be asked for in order to avoid this?

 

[DavidShe]

@ClassG33 It would be interesting to see what happens when you short the terminals on the speaker.

 

[ClassG33]

@ClassG33 It would be interesting to see what happens when you short the terminals on the speaker.

@DavidShe . How would I go about that? Sounds risky lol

 

[ClassG33]

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.

Two baking sheets did not make an audible difference, that I could notice. Tried convering various combinations of sides of the speakers and amps. Checked for change in left and right speakers placed farther away as well, but they still make noise as well.

 

[radix]

I would suspect if the toroid is on its side, then moving the amp below the speaker would significantly reduce the interference.

I'd still be interested in hearing what Mac support says about the situation. It seems like you should not be the first person to have this happen if it's normal for that specific amp.

My amp (MC2205) likely does not have toroidal transformers, so maybe the anecdote that it's 3" from an L100 speaker does not matter much.

 

[ClassG33]

I would suspect if the toroid is on its side, then moving the amp below the speaker would significantly reduce the interference.

I'd still be interested in hearing what Mac support says about the situation. It seems like you should not be the first person to have this happen if it's normal for that specific amp.

My amp (MC2205) likely does not have toroidal transformers, so maybe the anecdote that it's 3" from an L100 speaker does not matter much.

I did raise the speaker above the amp and held them up to my ear, and there was still noise. I'd say I listened as high as maybe 2ft. Above the amp. I have tried 360° around the amp, EXCEPT for directly beneath the amp, because obvious reasons lol

 

[ClassG33]

where they aluminum or steel? Aluminum might not make a difference. Steel should make a difference, but not sure how much. Maybe not an audible difference.

Guess I don't know haha!

I guess my goal here is to determine if this is indeed a problem - I am gathering that it's 95% sure to be a problem, based on experience from other people much more intelligent then me, plus the fact that I have listened to, setup and worked on many systems with McIntosh amps of even higher toroidal power (MC611, MC462), tube amps like the 275, ma352/252, etc.that have easily been within a foot of other B&W speakers, and do not have this issue. Also other brands with powerful toroidal amps, and never had the issue.
I consider the possibility of "maybe I just didn't notice at the time?" However this is too loud not to notice.

I have had this setup with an Arcam AVR20 which is toroidal, albeit lower power...

 

[DavidShe]

@DavidShe . How would I go about that? Sounds risky lol

Connect the positive speaker terminal to the negative speaker terminal using a short wire.

 

[ClassG33]

Connect the positive speaker terminal to the negative speaker terminal using a short wire.

Forgive my naivety, but wouldn't that be a good way to destroy the speaker and/or amp?

 

[Doodski]

Forgive my naivety, but wouldn't that be a good way to destroy the speaker and/or amp?

-If the amp's speaker terminals are shorted the amplifier will fry.
-If the amplifier is connected to the speakers and the speaker terminals are shorted the amp will fry.

-If the amplifier is not connected to the speakers with speaker wire then the speakers and amp are not electrically affected by each other.
(Except in your rare case with the mutual induction occurring.)

So... Do this. >>>
-Make sure the speaker is not connected with speaker wire to the amp.
-Then take a small piece of wire (Maybe several inches in length with bare metal ends.) and connect the speaker's positive to the same speaker's speaker negative terminal and that only shorts the speaker and the amp is not in the circuit in any way.
-Then power ON the amp and see if the speaker makes noise from mutual induction.

 

[DavidShe]

Forgive my naivety, but wouldn't that be a good way to destroy the speaker and/or amp?

Take care, as the magnetic field from your mighty McIntosh could cause sparks to fly when you short your speaker terminals!
(no that won't happen)

 

[Golf]

Here’s the last entry in ClassG33’s journal:

›After wasting two days with approaching the problem in a theoretical manner, tomorrow I shall short-circuit some inoffensive connectors.‹

 

[restorer-john]

The other interesting thing to consider is the induced signal in the speaker from the Mac's transformer could be very partially fed back to the input via the NFB loop and it could be modulated somewhat, depending on the fluctuations in the field due to currents flowing in all the channels whilst playing robust content.

I don't blame the McIntosh at all and it's not faulty IMO. Plenty of amplifiers have stray radiated fields from large transformers. Back in the vinyl and tape deck days, much time and effort was spent by me and millions of other audiophiles, carefully arranging HiFi components to ensure their transformers didn't induce noises in EQs, cassette decks and turntables. Knowing where the transformers were and moving things from right to left in cabinets, spacing and order of stacking was extremely important. But to get it in a unconnected loudspeaker is pretty awesome in my book.

You should simply move the amplifier to the other side of the cabinet, that will cut down the noise significantly I would expect, as the TXF is further away from the speaker and its internals (depending on where the inductors are inside), or preferably into its own cabinet or stand. You bought a beast of an amp and its letting you know that. I think you should also reach out to McIntosh service department and relate your experience- see what they have to say.

I remember once, years ago putting a loudspeaker on top of an amplifier I was testing and heard what I thought was a buzz in the unconnected speaker. I blamed the magnet assembly and the top panel of the amp and promptly forgot about it. I'll bet it was the same thing, but I dismissed it at the time as "impossible".

I've definitely had sensitive headphones that have picked up radiated mains and the concept is the same- but they were terminated.

Your experience, @ClassG33, encouraged me to investigate and work out just WTF was happening in your case.

If anyone wants some analyzer FFTs of the induced mains in the centre speaker drivers, from the toroidal in my pics I can do that in the morning? It is just a proof of concept that it could happen and be audible, not indicative of the OP's actual severity.

 

[Doodski]

If anyone wants some analyzer FFTs of the induced mains in the centre speaker drivers, from the toroidal in my pics I can do that in the morning? It is just a proof of concept that it could happen and be audible, not indicative of the OP's actual severity.

Yes, please! I want that very much. What is the input impedance of your spectrum analyzer? Just curious.

 

[Doodski]

@restorer-john. Oh! ...and. What is with all the storms you have where you live? You seem to have nasty ones too and often.

 

[Golf]

If anyone wants some analyzer FFTs of the induced mains in the centre speaker drivers, from the toroidal in my pics I can do that in the morning?

Your local mains frequency is 50 Hz? Would be interesting to see any difference based on the fact that ClassG33’s is 60 Hz, I believe.