Hum in Anthem MRX 700

AcuDefTechGuy

AcuDefTechGuy

Audioholic Jedi
- MVW and I have the same problem with our Anthem’s. Were on this post to see if anyone has had the same problem, what resolved it and what it cost to have it fixed.

- I actually have an Electronics Engineering Degree and nearly 50 years experience, I do know what I’m talking about.

- Mgood's problem is different than the original post, his sounds like the TV produces EMF radiation (or EMI: Electro Magnetic Interference) getting into the Anthem. Could be the proximity of the TV to the Anthem or cabling locations. It has nothing to do with “Harmonic Resonance”.

Here’s the lesson you must have missed when you went to college:

Electromagnetic Field (EMF) Radiation Spectrum
EMF radiation can be classified from very low frequency (long wavelength) to very high frequency (short wave length) as show below.
View attachment 33960
I'm out of here!
So in your 50 years of experience and knowledge with the Electronics Engineering Degree (is this the same as Electrical Engineering Degree?), what is the problem with Anthem? And do other AVR brands have this same problem?
 
W

WMH

Audiophyte
So in your 50 years of experience and knowledge with the Electronics Engineering Degree (is this the same as Electrical Engineering Degree?), what is the problem with Anthem? And do other AVR brands have this same problem?
Back in the 70’s it was called an Electrical Engineering degree, my elective coursework concentrated on analog and RF design. I’ve always worked on the Electronics side as opposed to Industrial.

I’ve set up the unit with just one speaker connected, but of course since the problem is intermittent, I could not get the hum to start. Tapping on the circuit boards had no effect. My intention was to isolate problem to a circuit board with an oscilloscope and then look for cold solder joints or possibly a bad component.

From what I’ve heard, Anthem doesn’t share/sell their schematics so troubleshooting could be difficult. It’s most likely the same sentiment as they only sell product though authorized dealers.

I’m surprised MGOOD even has his problem in Norway since EMI standards are much stricter in Europe than the US.
 
P

PENG

Audioholic Overlord
I think we are just guessing at this point..

mgood said:

- the hum is in coming from the unit itself, is constant regardless of the volume position (ref post#30), a real pain when he installed a LG OLED TV. I take it that it would hum even without any speakers connected, but that's just my guess.

- the he reported that "The receiver hums with the TV off, but now the noise goes up and down and is not as loud. ..." (ref post#47)

- he attached an audio clip of the hum in post#46, it did not sound like the typical grounding related 60/120 Hz or 50/100 Hz in part of Europe hum. It sounded like higher order harmonics

So again, it could be EMI related, but I do doubt EMI from that TV (even when it was off) would be so strong to make the transformer (again, his post#30 indicated the noise did not come from the speakers) hum that loud.

I remain curious about the real culprit and hope he will let us know when he eventually narrow things down.
 
AcuDefTechGuy

AcuDefTechGuy

Audioholic Jedi
Back in the 70’s it was called an Electrical Engineering degree, my elective coursework concentrated on analog and RF design. I’ve always worked on the Electronics side as opposed to Industrial.

I’ve set up the unit with just one speaker connected, but of course since the problem is intermittent, I could not get the hum to start. Tapping on the circuit boards had no effect. My intention was to isolate problem to a circuit board with an oscilloscope and then look for cold solder joints or possibly a bad component.

From what I’ve heard, Anthem doesn’t share/sell their schematics so troubleshooting could be difficult. It’s most likely the same sentiment as they only sell product though authorized dealers.

I’m surprised MGOOD even has his problem in Norway since EMI standards are much stricter in Europe than the US.
In my 30 years in this hobby, I've only used AVRs from Sherwood, Harman, Denon, Marantz, Pioneer, Sony, and Yamaha. And I have never seen a case where these AVRs would produce any kind of HUM noise like the 3 cases here with these Anthem AVRs.

I've had cases of ground loop hum noises with various amps in my previous homes, but never with an AVR.

Definitely gives AVRs a bad name and more ammunition for @TLS Guy race against the AVR-machines. :D
 
P

PENG

Audioholic Overlord
In my 30 years in this hobby, I've only used AVRs from Sherwood, Harman, Denon, Marantz, Pioneer, Sony, and Yamaha. And I have never seen a case where these AVRs would produce any kind of HUM noise like the 3 cases here with these Anthem AVRs.

I've had cases of ground loop hum noises with various amps in my previous homes, but never with an AVR.

Definitely gives AVRs a bad name and more ammunition for @TLS Guy race against the AVR-machines. :D
So AVRs are machines now:D:D, thanks to TLS?
 
M

mgood

Enthusiast
I think we are just guessing at this point..

mgood said:

- the hum is in coming from the unit itself, is constant regardless of the volume position (ref post#30), a real pain when he installed a LG OLED TV. I take it that it would hum even without any speakers connected, but that's just my guess.

- the he reported that "The receiver hums with the TV off, but now the noise goes up and down and is not as loud. ..." (ref post#47)

- he attached an audio clip of the hum in post#46, it did not sound like the typical grounding related 60/120 Hz or 50/100 Hz in part of Europe hum. It sounded like higher order harmonics

So again, it could be EMI related, but I do doubt EMI from that TV (even when it was off) would be so strong to make the transformer (again, his post#30 indicated the noise did not come from the speakers) hum that loud.

I remain curious about the real culprit and hope he will let us know when he eventually narrow things down.
I'm planning a barrage of tests and will keep you posted. Still waiting for the DC blocker, and will probably try and Isotek and maybe a Furman as well. The Anthem is in fact due for retirement soon, so I will also be borrowing a NAD T777 v3 (toroidal transformer) and a Denon X6500 (e-core transformer) to see how they behave. Will also try connecting to a different power socket.

About proximity to the TV: the Anthem is approx. 5 feet from the TV in a new Atacama rack with spikes. Might be my imagination, but the hum seems to have changed somewhat in character since I installed the rack. The receiver was previously in a IKEA unit. This would indicate a harmonics issue, no?

To everyone who has chimed in so far: thanks for all the feedback and suggestions.

To the OP: sorry about the thread hijack. I hope this thread can serve as a resource for other Anthem owners with similar issues.
 
P

PENG

Audioholic Overlord
I'm planning a barrage of tests and will keep you posted. Still waiting for the DC blocker, and will probably try and Isotek and maybe a Furman as well. The Anthem is in fact due for retirement soon, so I will also be borrowing a NAD T777 v3 (toroidal transformer) and a Denon X6500 (e-core transformer) to see how they behave. Will also try connecting to a different power socket.
I have never had a Denon hum on me. The X6500H, imo is superior to the T777 V3, unless you believe Dirac Live is superior.:D Toroidal is not always better than EI core, both have pros and cons, those in general they are lighter for the same VA rating. Yes all else being equal they have less leakage flux too but Denon's E-I core transformer are well build and you can typically see the copper foil/strap shielding on the outside to help minimize leakage flux.

The receiver was previously in a IKEA unit. This would indicate a harmonics issue, no?
No, it shouldn't.

You said it hums with the TV "off" too, but have you tried unplugging the TV's power cord all together to make sure it was really off?

If with power cord unplugged and the hum persists then we odd to look for something else.

Aside from the TV, have you added any other devices, including appliances prior to noticing the hum?
 
M

mgood

Enthusiast
First test was to replace the Anthem altogether. My local had a Denon X4500H demo unit that I've borrowed. No hum at all. Dead silent. The Denon is scorching hot though, but this seems to be normal with these units.

Will set up the Anthem in another room to see what results I get.
 
lovinthehd

lovinthehd

Audioholic Slumlord
First test was to replace the Anthem altogether. My local had a Denon X4500H demo unit that I've borrowed. No hum at all. Dead silent. The Denon is scorching hot though, but this seems to be normal with these units.

Will set up the Anthem in another room to see what results I get.
What are you doing to get it scorching hot?! Can always add cooling....
 
M

mgood

Enthusiast
What are you doing to get it scorching hot?! Can always add cooling....
Scorching hot might be a slight exaggeration. But it definitely runs hotter than the Anthem. My speakers are 4 ohms with 80-something sensitivity, which I’m sure doesn’t help.

I’ve seen people add cooling fans to the Denon and Marantz units. Might try this approach.
 
lovinthehd

lovinthehd

Audioholic Slumlord
Scorching hot might be a slight exaggeration. But it definitely runs hotter than the Anthem. My speakers are 4 ohms with 80-something sensitivity, which I’m sure doesn’t help.

I’ve seen people add cooling fans to the Denon and Marantz units. Might try this approach.
Coolerguys.com and acinfinity.com have some good choices.
 

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