I Googled a random power supply image for the peeps to see the layout and bridge. It is a 240 V AC + and - output supply for viewing purposes only. Not the actual power supply.
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McIntosh Transformer causing noise in speakers while disconnected.
- Thread starter ClassG33
- Start date
Take a look at the McIntosh marketing info at #62. A 30lb transformer and six 27,000 uF, 100V caps. NOT a SMPS! That's an old fashioned brute force linear power supply.
Yeah, I saw all that and was impressed of course... It's for sure low frequency stuff with high current mutual induction and @ what voltage I don't know. I'm interested in the audio power output and I'm going to hazard a estimate of maybe 25% more power supply voltage when unloaded than RMS power output will indicate ..brb... afk.
@ 250 Watts RMS @ 8R @ 7.9 A peak @ 63.2 V DC +/- (loaded).
+ 25% voltage when the power supply is unloaded = ~79 V DC +/-
For the AC secondary side of the bridge I don't remember exactly how to reverse calc that.
Can that induce energy power transfer across the air space to a speaker's crossover coils?
Is that enough energy to create mutual inductance power transfer of 60 Hz or does it have to be high frequency power transfer?
+ 25% voltage when the power supply is unloaded = ~79 V DC +/-
For the AC secondary side of the bridge I don't remember exactly how to reverse calc that.
Can that induce energy power transfer across the air space to a speaker's crossover coils?
Is that enough energy to create mutual inductance power transfer of 60 Hz or does it have to be high frequency power transfer?
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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 possibly eliminate the symptoms, even if it would not solve the root cause.
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 possibly eliminate the symptoms, even if it would not solve the root cause.
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A DC voltage and current flow would develop a electromagnetic field around the transformer primary but it would not be the AC signal we hear in the recording. It would be incapable of transferring energy like AC energy does. It would be a steady state EMF around the toroidal that does not collapse and then develop again like a AC voltage and current does.
@Zapper said that there must be a very high frequency fundamental for the power transfer to occur across the air gap. He said the 60 Hz energy from the McIntosh power supply will not transfer power the way things are transferring at this time. My RF theory is at best lame and so I have no ideas about that.
Extreme_Boky
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Yeah... but then we won't know what's causing it... that'd be an easy way out.
radix
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Have you verified your outlet has a proper ground? You can get an inexpensive socket tester.
A really good chunk of the $ for that amp is the fantastic McIntosh service. Have you called them or your dealer? I'd definitely call them before trying to move that thing and re-box it.
A really good chunk of the $ for that amp is the fantastic McIntosh service. Have you called them or your dealer? I'd definitely call them before trying to move that thing and re-box it.
Golf
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What about restricting your analysis to a portion with mostly hum only? Like somewhere here:
Sokel
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I restricted it to the clean channel so I have enough samples (doesn't work with too few) :
If the sample location on the signal sweep can be set anywhere on the signal sweep then one needs to ensure that they get the sample at a sample waveform slope where the frequency is the fundamental of 60 Hz as it has been confirmed to be by the FT analysis graph provided by @mhardy6647.
The issue of the varying and distorted sine wave irregularity creates a problem for metering the 60 Hz fundamental because the slope of the distorted 60 Hz waveform varies randomly.
The fundamental frequency of 60 Hz is calculated from the slope of the rising edge or the falling edge of the waveform.
In this Frequency Analysis graph the fundamental is 60 Hz and anything to the right are odd and even order harmonics.
Because the measured waveform is randomly changing slightly and distorted the proportions of harmonics are not textbook picture perfect as you might be accustomed to.
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- Thread Starter
- #177
I have moved the speakers but haven't taken the amp off the cabinet. I can carry the center speaker in my hands, and it will produce this sound as I hold it within range of the amp. I've slid the tower speakers closer to the cabinet, and they begin to make the noise as well, again 100% disconnected.
- Thread Starter
- #178
It does not change. You can see in the video I do not even have them turned on. I considered that as well.
- Thread Starter
- #179
How would one go about reaching out to them specifically?
- Thread Starter
- #180
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.
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