McIntosh Transformer causing noise in speakers while disconnected.

[ClassG33]

Did you use a standard power cord?

Yeah that's how I started, as per the manual. My Panamax and Marantz normally use the AQ cables, but I switched to the AQ cable from the Marantz first, then I tried into the Panamax. No results so switched back.

 

[ClassG33]

It is a serious issue as @Zapper stated. It is not a natural thing as you say. It is a fault.

In other words, send the amp back for replacement and should be good to go?

 

[Doodski]

In other words, send it back for replacement and should be good to go?

Sounds very good. Be safe.

 

[ClassG33]

Sounds very good. Be safe.

To Clarify - it is definitely an issue with the amp, and not the speakers, right? Just want to make sure I am not crazy and take the advice 100% before packaging this 120lbs. Beast

 

[mhardy6647]

"When the only tool you have is a hammer, all of your tools look like nails."
I just ripped a bit of it with Audacity -- here's what it looks like: I am not skilled at pulling real information out of their data, but I am sure it can be done
EDIT: Pay no heed to the absolute time on the x-axis! I didn't start the capture at time zero.

 

[DonH56]

Sounds like 60 Hz and harmonics from the power supply to me. The amp has a toroidal transformer which should reduce its radiated field, and is enclosed in its own shield (box), but there are power supply rectifiers and such that will generate high-frequency hash. I agree with the others; I would contact McIntosh. Hopefully just a shielding problem, like paint/plating over case screws preventing good grounding of the case.

There are materials you can buy for shielding but they are likely to be expensive, difficult to install, and you should not need them in a consumer installation. That said, I would look for a different console, or a separate stand for the amp, just in general to get some space and better airflow around the amp.

IMO - Don

 

[DonH56]

View attachment 357697

I just ripped a bit of it with Audacity -- here's what it looks like: I am not skilled at pulling real information out of their data, but I am sure it can be done

Can you run an FFT on that? The spectral information would be useful to us and to McIntosh.

 

[Doodski]

To Clarify - it is definitely an issue with the amp, and not the speakers, right? Just want to make sure I am not crazy and take the advice 100% before packaging this 120lbs. Beast

It's the amp... @Zapper would know better than I if the power supply has a issue and is emitting/broadcasting a distorted 60 Hz sine or if it might be a distorted 120 Hz sine. Could the amp section be amplifying and broadcasting at a high voltage? @ClassG33 you have used the amp for listening to audio and it sounded OK?

 

[ClassG33]

View attachment 357697

I just ripped a bit of it with Audacity -- here's what it looks like: I am not skilled at pulling real information out of their data, but I am sure it can be done

Nicely done. You'd need a EQ Plug-In that can show you frequency output. Like FabFilter. Idk if there are any free ones for Audacity.

I'll take a moment later and count the amount of cycles between 10.320 and 10.520, but it looks like there are about 6.0 peaks per .010 seconds, which is a divisible of a 60 hz cycle lol soooooo

 

[ClassG33]

It's the amp... @Zapper would know better than I if the power supply has a issue and is emitting/broadcasting a distorted 60 Hz sine or if it might be a distorted 120 Hz sine. Could the amp section be amplifying and broadcasting at a high voltage? @ClassG33 you have used the amp for listening to audio and it sounded OK?

According to his sample, it's about 600Hz, or a distorted 120Hz and harmonics of it.

But playing audio sounds fantastic.. the audio output is louder than the noise, but I've listened to a lot of Mono Block setups, etc. set up right next to 800 diamond series, and never had this issue with other amps I've used.

 

[Doodski]

According to his sample, it's about 600Hz, or a distorted 120Hz and harmonics of it.

Because the waveform is distorted it lends it that clicky sort of buzzy sound to the sine wave. A pure and nicely rounded 60 Hz, 120 Hz or a 600 Hz sine waveform sounds very different and is smooth sounding. I have experienced the overall sound of this distorted waveform before from faulty amplifiers but never when the speaker is disconnected from the amp. That is actually very concerning for me. Return it and get a new one for sure.

 

[ClassG33]

Because the waveform is distorted it lends it that clicky sort of buzzy sound to the sine wave. A pure and nicely rounded 60 Hz, 120 Hz or a 600 Hz sine waveform sounds very different and is smooth sounding. I have experienced the overall sound of this distorted waveform before from faulty amplifiers but never when the speaker is disconnected from the amp. That is actually very concerning for me. Return it and get a new one for sure.

I have a background of Audio Engineering, just not electrical engineering, so that is all lingo I can relate to. I'm so bummed man.

 

[Doodski]

I have a background of Audio Engineering, just not electrical engineering, so that is all lingo I can relate to. I'm so bummed man.

This is a rare circumstance and McIntosh gear is usually infallible and reliable as can be. So no fear...

 

[GXAlan]

This is amazing. Maybe the McIntosh is broken, maybe not. This does make me wonder if there's some sort of perfect storm where cable lifters or something crazy like that can actually work.

The good thing is that McIntosh will either know it's a problem or have an answer for you. Besides reliability, they have good customer service. I often see McIntosh gear close to speakers at Best Buy and I don't hear that kind of noise, so I imagine it's a glitch.

 

[Extreme_Boky]

In other words, send the amp back for replacement and should be good to go?

That will not help, the issue will still be there.

That amp is a solid state amp and I could not find any information on its power supply. I hope that McIntosh would not do silly things... like use SMPS. If they did (use SMPS), get rid of the amplifier as fast as you can, and buy something else that uses a linear power supply.

The root cause is the magnetic coupling between the mains transformer inside the amp, and the crossover inductor coils (iron-cored, or one would hope -> air-cored) and/or speaker coils inside the speaker cabinet.

The solution is (much) better magnetic isolation - mu-metal iron sheets/ribbons, wrapped around the transformers inside that amp.

You can't change the above... so your only hope is to either:
- provide more space between the amp & speaker
- place a large mu-metal sheet barrier between the amp and speaker (very ugly.... unless you wrap it in leather or something and make it a decorative piece... that may work!)
- place the speaker crossover inside the mu-metal box.. that's inside the speaker.... but there are still speaker coils that you can't isolate from magnetic radiation...

So, more space is the solution... or get a different amplifier, but check the inside photos first to see if they isolated the transformers properly

The bottom line... both manufacturers failed miserably at isolating their products from magnetic interference... speakers (drivers) can be isolated too !!!

 

[Golf]

Trying to »visually count« some peaks, I’d tend to say it is 150 Hz. 15 peaks within one tenth of second

 

[Doodski]

I hope that McIntosh would not do silly things... like use SMPS.

The PWM would be maybe ~20 kHz, ~50 kHz and maybe up to ~hundreds of kHz if a super high frequency PWM so I don't think it could cause a 60 Hz or 120 Hz buzz in the speaker. Unless you have more info I am not aware of...<?>

failed miserably

This is twigging my curiosity. To release a product that in all units has the fault would be a horrible faux pas.

 

[ClassG33]

The PWM would be maybe ~20 kHz, ~50 kHz and maybe up to ~hundreds of kHz if a super high frequency PWM so I don't think it could cause a 60 Hz or 120 Hz buzz in the speaker. Unless you have more info I am not aware of...<?>

This is twigging my curiosity. To release a product that in all units has the fault would be a horrible faux pas.

SMPS? PWM?

 

[Doodski]

Trying to »visually count« some peaks, I’d tend to say it is 150 Hz. 15 peaks within one tenth of second



View attachment 357709

As you say 150 Hz seems a close timing approximation then it must be a 120 Hz distorted sine. That's the only way this could go down is it's the energy @ the bridge if 120 Hz. But @Extreme_Boky has very solid ideas about this as well.

 

[Doodski]

SMPS? PWM?

SMPS = Switch mode power supply.
PWM = Pulse width modulation.