How to eliminate 120hz ground noise

[blestin]

How should

As @Jbrunwa mentioned, the Denon AVR has a 2-prong power connector, so no ground connection. I would try grounding the chassis, via the grounding screw near the phono input, to the power strip. Generally, I like to ground everything properly first, then only if the problem persists look at breaking loops.

What part of the power strip do I attach the ground wire from the avr?

I

 

[blestin]

“Since HDMI should not be caring much one way or another [1], you may divert them to ground either at the TV itself (e.g. via a satellite / cable / antenna connection or a shielded network cable to an earthed switch or other apparatus) or at the receiver (shielded network cable, phono grounding”

This sounds like a solution, but I do not fully understand how to do this. Do I simply connect a cable and then connect that cable other device connected to ground. Or connect an antenna to the tv and plug it in to a grounded outlet?

 

[ebslo]

What part of the power strip do I attach the ground wire from the avr?

For a permanent connection I was thinking something like this but you may be able to use something homemade as a test first.

 

[blestin]

As Harmonie suggested, since the AVR is isolated this will most likely not work, but I will try anyways

 

[Cuniberti]

Maybe someone can help me out here with a technical problem. I am having a buzzing noise (maybe 120hz) coming out of my BMR tweeter and I figured out it is caused by a ground loop. I finally pinpointed it to my TV, by connecting a ground lift the the power cord which eliminated the the buzzing. (Warren Coleman’s advise)

Obviously a ground lift is a not a safe long term solution, what device do I need to purchase to eliminated this ground noise?

Warren from VTV recommended I try “adding a 100 ohm resistor from outlet ground to the ground tab and see if that breaks it.” Not sure how to go about doing that.

Options: Ebtech Hum X or Furman AC-215A power conditioner

Balanced Power with a Equitech Son of Q
https://proaudioboutique.com/products/equitech-son-of-q

 

[Harmonie]

I'm NOT a technician nor an expert.
But before using external devices that would "disguise" the hum, my common sense says check the root of the cause and don't try to cure it with some other artefact.
If the DENON is the cause, then maybe it has some issue ?
Is it common to have such issues with such well known brand ?
Why don't you check with the manufacturer ?
If the issue is not the amp, then it means that either your set-up is not well plugged or your electrical installation is the cause.
Maybe your interconnects and your power cords are running in parallel and you should either keep them apart or cross them in 90° so that the interconnects don't pick up noise.

 

[blestin]

I'm NOT a technician nor an expert.
But before using external devices that would "disguise" the hum, my common sense says check the root of the cause and don't try to cure it with some other artefact.
If the DENON is the cause, then maybe it has some issue ?
Is it common to have such issues with such well known brand ?
Why don't you check with the manufacturer ?
If the issue is not the amp, then it means that either your set-up is not well plugged or your electrical installation is the cause.
Maybe your interconnects and your power cords are running in parallel and you should either keep them apart or cross them in 90° so that the interconnects don't pick up noise.

The issue is definitely with the TV , as lifting the ground on the TV power plug eliminates the issue.

 

[Harmonie]

Yiour TV is surely a 2 prong too, right ?
You can always reverse the TV power cord (turning it by 180°) .
Check your interconnects and your TV power cord if running in parallel ? Keep them apart or cross them in 90° so that the interconnects don't pick up noise

How about a Cable TV Ground Isolator

Just came across this
https://www.audioholics.com/home-theater-connection/ground-loops-eliminating-system-hum-and-buzz

 

[blestin]

Yiour TV is surely a 2 prong too, right ?
You can always reverse the TV power cord (turning it by 180°) .
Check your interconnects and your TV power cord if running in parallel ? Keep them apart or cross them in 90° so that the interconnects don't pick up noise

How about a Cable TV Ground Isolator View attachment 121839

Just came across this
https://www.audioholics.com/home-theater-connection/ground-loops-eliminating-system-hum-and-buzz

The TV is 3 prong , lifting the ground by using a ground lift eliminates the buzz.

The TV powercord is not close to any other wires.

 

[sal]

I had a similar issue and it turned out to be my XLR cables running from the preamp to the amp (with a VTV amplifier). I bought some cheap $13 XLR cables from amazon and it fixed the problem.
The way I found the issue was by removing the XLR cables at the amp and turned the amp on. The noise went away when I did

 

[Harmonie]

TV's in Europe are mostly 2 prong and isolated, that's why I asked.
TV's power cord is not in the same socket as the rest of the gear ? (It would be better, to have only one common ground).

 

[blestin]

TV's in Europe are mostly 2 prong and isolated, that's why I asked.
TV's power cord is not in the same socket as the rest of the gear ? (It would be better, to have only one common ground).

I tried connecting it the same surge protector and it made no difference, I have it plugged in separately so I can easily extend the tv and keep the cable out of sight

 

[Jbrunwa]

Just a thought. With both TV and Denon on and video input set to the TV HDMI, do you still hear the hum if you change the audio input from HDMI to optical?

 

[blestin]

Well thank you all for the help, I solved the problem by deciding I prefer my old AVA 600R to the Purifi Eval1. Packed up the Eval1 and setup my old amp.

The problem does not occur with my old amp because is has a grounding switch that when turned to off eliminates the buzz. So problem solved.

I really appreciate the epic effort.

 

[AnalogSteph]

Quite peculiar, this. Like @Harmonie says, I was expecting the TV to be a floating affair with 2-prong mains lead, but if it's the ground loop between the TV and power amp via AVR that's giving problems I'm a bit puzzled. You see, with the Benchmark RCA --> XLR cables that particular connection should have a decent amount of common-mode rejection - not super high but something in the 30-40 dB range at least (depending on the ratio of output and input impedances), which should keep most issues at bay in real life.

Either that still is not enough, or the connection of HDMI shield to audio output ground within the AVR is rather more convoluted and less direct than what I would have expected. We are, after all, talking a brand with a bit of a history with less than ideal grounding practices in relation to HDMI ports.

Providing galvanic isolation between either the TV and AVR (e.g. via Toslink) or the AVR and power amp (e.g. with a line isolator) would be a last resort. Either would be likely to fix the hum but both come with some pitfalls. Toslink has limited bandwidth so the format options are quite limited (either stereo PCM up tp 24/96 or 24/192, or compressed AC-3 or DTS audio), and line isolators may be quite high impedance and only suited for used at an amplifier input.

Well thank you all for the help, I solved the problem by deciding I prefer my old AVA 600R to the Purifi Eval1. Packed up the Eval1 and setup my old amp.

The problem does not occur with my old amp because is has a grounding switch that when turned to off eliminates the buzz. So problem solved.

Well, that's another way of solving this issue, of course.

The Eval1 may be better suited for setups with a balanced output DAC or similar, not so much for an unbalanced/balanced hodgepodge like yours. A more traditional hi-fi power amp is a better match overall. I looked up the specs, and got

The Fet Valve 600R produces 300 watts per channel, 20 to 20 kHz into 8 ohms at less than 0.01% THD. Eight double-die output transistors, standard on the Fet Valve 600R, handle challenging speaker loads (2 Ohm loads and up).

Sounds like a good one.

 

[blestin]

Quite peculiar, this. Like @Harmonie says, I was expecting the TV to be a floating affair with 2-prong mains lead, but if it's the ground loop between the TV and power amp via AVR that's giving problems I'm a bit puzzled. You see, with the Benchmark RCA --> XLR cables that particular connection should have a decent amount of common-mode rejection - not super high but something in the 30-40 dB range at least (depending on the ratio of output and input impedances), which should keep most issues at bay in real life.

Either that still is not enough, or the connection of HDMI shield to audio output ground within the AVR is rather more convoluted and less direct than what I would have expected. We are, after all, talking a brand with a bit of a history with less than ideal grounding practices in relation to HDMI ports.

Providing galvanic isolation between either the TV and AVR (e.g. via Toslink) or the AVR and power amp (e.g. with a line isolator) would be a last resort. Either would be likely to fix the hum but both come with some pitfalls. Toslink has limited bandwidth so the format options are quite limited (either stereo PCM up tp 24/96 or 24/192, or compressed AC-3 or DTS audio), and line isolators may be quite high impedance and only suited for used at an amplifier input.

Well, that's another way of solving this issue, of course.

The Eval1 may be better suited for setups with a balanced output DAC or similar, not so much for an unbalanced/balanced hodgepodge like yours. A more traditional hi-fi power amp is a better match overall. I looked up the specs, and got

Sounds like a good one.

Came down to preference and system compatibility in the end.
I get way more gain on my old amp in my setup