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Advice Needed: Can't kill the buzz, but the buzz is killing me.

isomorphZeta

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I'm just about at my wits end trying to troubleshoot this.

Just moved into a new house, and added some new equipment in the move, so there are a lot of variables at play here. Despite that, I've tried to be methodical in tracking down the issue.

Issue:
When powering on the KEF LS50W speakers (connected to the Onkyo TX-RZ50 AVR via the Front pre-out RCA jacks, from the Aux RCA jacks on the speakers), a moderately loud buzz is heard. If the AVR is switched off, this buzz gets very loud. If the KEF speakers are switched to a different input, no buzz is heard. This is the case for active inputs (Optical, connected to TV) and inactive inputs (wireless and bluetooth).


Previous setup:
  • HARDWARE
  • AVR: Integra DRX-3.3

  • SPEAKERS
  • Front: KEF LS50W
Current setup:
  • HARDWARE
  • AVR: Onkyo TX-RZ50
  • Multizone Amplifier: Rotel RMB-1506
  • Power Source/Conditioner: Furman ELITE15 DM i

  • SPEAKERS
  • Front: KEF LS50W
  • Center: MartinLogan Motion 30
  • Rear: Polk 80 F/X-LS (in-ceiling)
  • Subwoofer: Polk HTS-12
  • Zone 1: 2x Origin Acoustics D67
  • Zone 2: 2x Origin Acoustics D67
  • Zone 3: 2x Origin Acoustics D65EX (outdoor)

Background:
At my previous house, with the previous setup, I had the KEF LS50W speakers connected to my Integra DRX-3.3 via the Zone 2 / Zone B (Line Out) RCA jacks, and had sound output to these speakers via Zone B. It wasn't ideal, but that AVR didn't have RCA pre-outs, so that was the only way I could get the KEF LS50W speakers to work with that setup. There was no buzz, no hum - no issues at all.

Moving to the new house, I introduced a bunch of new equipment and different configurations to muddy things up. After getting everything connected, I powered up the KEF speakers and was met with a horrible, very audible "buzz". Not a hum, but a distinct, low frequency, sawtooth-y buzz.

"Okay, so something's introducing noise. New house, something was wired up weird, or maybe one of the new pieces of equipment is causing this?"

I disconnected everything from the new AVR, and just had the KEF speakers connected to them via the RCA cables: buzz.

I moved the AVR power from the Furman power conditioner (some "power conditioner", huh?) to the another outlet on the same circuit: buzz.

I moved the KEF power to the same outlet as the AVR: buzz.

I moved both to a different circuit: buzz.

I tried different power cables, different RCA cables: buzz, buzz.

"Alright, so that means it's definitely a ground loop, right? I read a bunch about them, and they can be caused by poor grounding at your panel. The builder has cheaped out on other stuff - maybe it's a bad ground?"

Drove an 8' copper-clad ground rod as far into the ground as I could (hit bedrock at 6', so I lopped off the remainder), 8' away from existing ground rod, and connected it in series in what I believe to be an NEC-approved dual ground rod setup: buzz.

"They make products that supposedly kill ground loops, so how about I just try one of those?"

Bought this thing, hooked it up: buzz. Thought maybe I had it backwards, swapped the connection around: louder buzz.

"Well... how about I grab the old Integra AVR and hook it up the way I had it before; see if that quiets things down."

I hooked the old Integra DRX-3.3 up to the KEF LS50W speakers the way it used to be set up, plugged them both into the Furman conditioner: buzz.

Moved them both from the Furman to a different outlet on the same circuit: buzz.

Different circuit: buzz.

"What the hell?! Okay, so I keep seeing people mention cable TV boxes introducing noise. Ah, but I don't have mine hooked up yet... Suddenlink did install an Arris RFoG, though, and that's got RG6 coax that runs in the walls, so... let's look at that."

Disconnected the Arris RFoG device: buzz.

And that brings us to where I'm at today: out of ideas.

The issue clearly seems to have something to do with the KEF LS50W speakers, since the buzz is present on the Onkyo and Integra AVRs. But what the hell do I do to fix it? Short of selling the KEFs and just going for more traditional, passive speakers (which I'm honestly not at all opposed to at this point), I honestly don't know.

I'm hoping someone on here far more knowledgeable about this than me is reading this and thinking "Ah, yep, it's because [this]. You just need to do [that] and you'll stop pulling your hair out!"

Fingers crossed, and thank you all in advance!
 
OP
I

isomorphZeta

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Bump. Hoping someone has some ideas for fixing this issue that I might be missing!

Or maybe someone out there has a nice set of passive speakers and really wants some KEF LS50Ws
 

McFly

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Can you try this for me - can you run a cable from the ground pin by the phono jacks on your avr or alligator clip a cable on the chassis somewhere to a known ground - e.g. your ground rod or probably the chassis of your toaster or fridge - something with a known ground?

I see your AVR and your external amplifier have no ground connections at all. They only use 2 pin live(hot) and neutral connectors. The two of them combined will have a lot of leakage (non hazardous, as eddy currents in their chassis amongst other things) once connected to you guessed it, your kef ls50w's which have 3 pin power cables and a nice ground for all that leakage to rush down.

I.E. get a fkn ground on that AVR chassis and it should all vanish there instead of make its way to the kefs ground, through the sensitive kef input circuitry.

Let me know how that goes
 
Last edited:

robwpdx

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A buzz compared to a tone would suggest a switching power supply as the source. You have the LS50's connected to the Furman to filter that out on the LS50 AC mains? Is there a gain setting on the LS50 aux input?

What is new in your house with a switching power supply or inverter power supply? Refrigerators, air conditioners, heat pumps, a new TV? Do them turning on and off affect the buzz? Are you near any very large radio transmitters, especially digital transmitters? The other thing you could do is make a small RCA jack terminating plug with say a 10K resistor and plug it in to the aux in, with the RCA jack shield on and off. That eliminates the cable to the AVR and the AVR.

I would try a https://www.bhphotovideo.com/c/prod...rmers_ci_2rr_line_input_isolator_stereo.html/ rather than that automotive one, you can always return it if it doesn't work.
 
Last edited:

McFly

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I really doubt its a SMPS. Its massive transformer eddy currents from two unearthed amplifiers making thier way to the only true ground which is on the kefs. You could try ground lift the kefs but it would be against electrical code. Get an earth on the AVR and it should vanish, I had the exact same problem when I hooked an earthed power amplifier to the preouts of my unearthed Denon AVR. Got mains ground earth on the denon chassis and poof silence.
 

wwenze

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To me what gives the most hint is this statement:

"hooked the old Integra DRX-3.3 up to the KEF LS50W speakers the way it used to be set up"

"Bought this thing, hooked it up: buzz. Thought maybe I had it backwards, swapped the connection around: louder buzz."

This thing blocks common-mode noise. The fact that this doesn't work, plus other observations, suggests to me that the noise is differential to begin with i.e. it is coming out from your AVR. You can verify that by plugging your headphone or portable headphone amp or something to the AVR's RCA out.

So what is likely happening, is that... Your house's AC power is very bad. To the point that the equipment's transformer might not even be operating normally and may be causing higher-than-usual coupling with distorted waveforms. Modern day electrical design safety practices like to use isolation transformer to protect everything (hence the lack of earth pin) but this causes secondary side (including the chassis) to float to half AC which is actually not a problem with proper design since the whole equipment floats together and the differential voltage (at the RCA pins) should be zero. However if there is a huge coupling issue then all bets are off since the RCA ground and signal pin can be coupled to different amount.

Earthing the chassis of your equipment can help since it reduces the total voltage swing from mains earth, but it won't help any differential voltage that still remains on the RCA.

An amp or AVR running on SMPS handles bad AC better so perhaps borrow one to check? LS50W also uses SMPS... Which is perhaps why it works on its own.
 

sam_adams

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"Alright, so that means it's definitely a ground loop, right? I read a bunch about them, and they can be caused by poor grounding at your panel. The builder has cheaped out on other stuff - maybe it's a bad ground?"

Drove an 8' copper-clad ground rod as far into the ground as I could (hit bedrock at 6', so I lopped off the remainder), 8' away from existing ground rod, and connected it in series in what I believe to be an NEC-approved dual ground rod setup: buzz.

This won't fix a 'ground loop' problem because the chassis safety ground returns to the service panel and is bonded with the neutral conductor there and only there. In a residential 'split phase' AC circuit, the current returns to the point of origin which is the transformer on the utility pole. The ground rod is present only to provide a path to the earth in the event of a lightning strike to the utility pole.
 

sam_adams

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"Well... how about I grab the old Integra AVR and hook it up the way I had it before; see if that quiets things down."

I hooked the old Integra DRX-3.3 up to the KEF LS50W speakers the way it used to be set up, plugged them both into the Furman conditioner: buzz.

Moved them both from the Furman to a different outlet on the same circuit: buzz.

Different circuit: buzz.

Chassis currents in the AVR are flowing through the shields of the RCA cables inducing a voltage into the center conductor of the interconnect. Either ground the chassis of the two speakers to the AVR to provide a lower impedance path for those currents to flow or isolate them with transformers at the inputs to the speakers using a Jensen CI-1RR.
 
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isomorphZeta

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Can you try this for me - can you run a cable from the ground pin by the phono jacks on your avr or alligator clip a cable on the chassis somewhere to a known ground - e.g. your ground rod or probably the chassis of your toaster or fridge - something with a known ground?

I see your AVR and your external amplifier have no ground connections at all. They only use 2 pin live(hot) and neutral connectors. The two of them combined will have a lot of leakage (non hazardous, as eddy currents in their chassis amongst other things) once connected to you guessed it, your kef ls50w's which have 3 pin power cables and a nice ground for all that leakage to rush down.

I.E. get a fkn ground on that AVR chassis and it should all vanish there instead of make its way to the kefs ground, through the sensitive kef input circuitry.

Let me know how that goes

Interesting! Okay, yeah, let me see what I can do. I've got some small gauge wiring lying around that I can probably use to fashion a ground. So I'll just run some cable from the phono ground pin to, let's say, the chassis ground on my refrigerator in the room over?

Currently the phono ground is running to my Debut Carbon turntable, but I did try removing that (I know that's not what we're testing here - just thought I'd mention it) with no impact to the buzz. I also didn't hook the phono ground up to anything when testing the Integra AVR.

Thank you!

A buzz compared to a tone would suggest a switching power supply as the source. You have the LS50's connected to the Furman to filter that out on the LS50 AC mains? Is there a gain setting on the LS50 aux input?

What is new in your house with a switching power supply or inverter power supply? Refrigerators, air conditioners, heat pumps, a new TV? Do them turning on and off affect the buzz? Are you near any very large radio transmitters, especially digital transmitters? The other thing you could do is make a small RCA jack terminating plug with say a 10K resistor and plug it in to the aux in, with the RCA jack shield on and off. That eliminates the cable to the AVR and the AVR.

I would try a https://www.bhphotovideo.com/c/prod...rmers_ci_2rr_line_input_isolator_stereo.html/ rather than that automotive one, you can always return it if it doesn't work.

Yes, I've tested having both the KEF speakers and Okyno and Integra AVRs connected to the Furman, straight to the receptacle, and to the receptacle on a different circuit. I can set the gain on the LS50Ws via the volume control. If I turn that down the buzz does quiet down, but it's not present at all on other inputs - even when the gain is turned up. For whatever that's worth.

This is a whole new house we just moved into, so the refrigerator, dishwasher, and A/C are all new. Same TV was brought over (LG CX). I've not thought to try turning them off, but I'll give that a shot after testing @McFly's ground idea. Then as a last ditch I've got that Jensen ground isolator.

Thanks for the tips!

The AVR and the KEFs need to be tied together and then to ground/earth as @McFly suggests.

How would I go about tying both together and grounding them? I'm planning to test grounding the AVR, but what would a long-term solution look like?


To me what gives the most hint is this statement:

"hooked the old Integra DRX-3.3 up to the KEF LS50W speakers the way it used to be set up"

"Bought this thing, hooked it up: buzz. Thought maybe I had it backwards, swapped the connection around: louder buzz."

This thing blocks common-mode noise. The fact that this doesn't work, plus other observations, suggests to me that the noise is differential to begin with i.e. it is coming out from your AVR. You can verify that by plugging your headphone or portable headphone amp or something to the AVR's RCA out.

So what is likely happening, is that... Your house's AC power is very bad. To the point that the equipment's transformer might not even be operating normally and may be causing higher-than-usual coupling with distorted waveforms. Modern day electrical design safety practices like to use isolation transformer to protect everything (hence the lack of earth pin) but this causes secondary side (including the chassis) to float to half AC which is actually not a problem with proper design since the whole equipment floats together and the differential voltage (at the RCA pins) should be zero. However if there is a huge coupling issue then all bets are off since the RCA ground and signal pin can be coupled to different amount.

Earthing the chassis of your equipment can help since it reduces the total voltage swing from mains earth, but it won't help any differential voltage that still remains on the RCA.

An amp or AVR running on SMPS handles bad AC better so perhaps borrow one to check? LS50W also uses SMPS... Which is perhaps why it works on its own.

Yeah, that's what I was afraid of. How even would I go about identifying and, more importantly, fixing dirty/bad power? I'd hoped the Furman might, I don't know, "condition" our power and clean things up if that were an issue (it was a pre-emptive purchase at a great price, since I'd added so much new equipment in the new house) but it doesn't seem like it's doing much of anything.

This won't fix a 'ground loop' problem because the chassis safety ground returns to the service panel and is bonded with the neutral conductor there and only there. In a residential 'split phase' AC circuit, the current returns to the point of origin which is the transformer on the utility pole. The ground rod is present only to provide a path to the earth in the event of a lightning strike to the utility pole.

Interesting. So the current flow (if there ever is any) across grounded devices in the house ends up terminating at the transformer, not the ground rod / earth? I've not cracked open the panel outside, but I figured code would have ground wires on their own path, not bonded to the neutral. There's an IBTB mounted below the panel that only appears to have bare ground wire running to/from it, so I'd assumed everything ground-related followed a path to the ground rods.



Thanks to everybody for taking the time to read all of this and weigh in. Sounds like I've got plenty of new ideas to try!
 

sam_adams

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So the current flow (if there ever is any) across grounded devices in the house ends up terminating at the transformer, not the ground rod / earth? I've not cracked open the panel outside, but I figured code would have ground wires on their own path, not bonded to the neutral.

NormalCurrentInBranchCircuit.png
 
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isomorphZeta

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So before dragging a cable across the house to connect the AVR up to our refrigerator's chassis ground, I decided to bring my UPS over (which has a TVSS ground screw) and try using that for the grounding point.

20230622_170959.jpg


I plugged the UPS into the wall (not the Furman, though I don't think it matters), ran some small 18AWG from the TVSS ground to the phono ground on the AVR, powered up the AVR, powered up the KEF speakers, and... silence!

Well, relative silence - there was still some hiss if you listened for it - but no more buzz! So hot damn, good call @McFly!

Now, interestingly, when turning the AVR off and leaving the KEF speakers on, I still got a harsh buzzing from the KEFs. Nothing near as bad as it was before (it was so loud prior to running this ground cable that I worried it would damage the speakers over time), but still audible to the point of being disruptive.

I didn't plan on having a UPS as a part of my AV stack, but if it keeps the speakers from buzzing I'll do it. Are there any more permanent solutions now that we seem to have the culprit identified? Seems like I just need to find a way to permanently ground the AVR chassis, right?

Thanks again to everybody that's taken time to read this, weigh in, and offer advice. This is why I love communities like this! I seriously can't thank y'all enough - it's been a stressful past couple months, and having something that's supposed to be enjoyable (listening to music / watching shows to unwind) turn into a stressful, frustrating, seemingly unsolvable problem sucks. I'm overjoyed to be making progress on this!
 

McFly

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Sick of these damn manufacturers using 2 pin mains leads ;)
 

Andysu

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Sick of these damn manufacturers using 2 pin mains leads ;)
surprised you lot all haven't been electrocuted with dodgy usa mains , no earth connection
 

SSS

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Sick of these damn manufacturers using 2 pin mains leads ;)
When all of the audio eqipment had only the 2 pin mains connection (what many of the 1970-80 gear had) then there is no ground loop problem due to the safety earth connection of one (normally then no problem) or more units (problem possible). By the way, with Furman power conditioners there I had a problem due to magnetic hum induction to audio line wires from the coils in the Furman.
 

McFly

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And then your vintage amp kills you one day due to a hot wires insulation breaking down and its sitting on the chassis somewhere. /s
 

SSS

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And then your vintage amp kills you one day due to a hot wires insulation breaking down and its sitting on the chassis somewhere. /s
Never had an isolation break down on my equipment with 2 pin mains. The transformers are specially protected between primary and secondary. And proper layed and secured mains voltage wires are stable and isolation will not break. But I agree that for todays switching power supplies much more is on the mains voltage side. And for manufacturers it is easier to have safety ground connection which reduces their liability in case of an accident.
 
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RandomEar

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I didn't plan on having a UPS as a part of my AV stack, but if it keeps the speakers from buzzing I'll do it. Are there any more permanent solutions now that we seem to have the culprit identified? Seems like I just need to find a way to permanently ground the AVR chassis, right?
Any device with a three prong plug and a metal case can serve as the source for the ground connection. Technically, you could also go buy an "empty" three prong plug, disconnect the hot and neutral pins and just wire up the safety ground, then connect this with the phono ground screw on your AVR. But please only do that if you know how to work with mains power cabling and have checked that the safety grounds on all receptables in your house are wired up correctly.

An alternate and possibly cleaner solution would be to switch to an optical connection from your AVR to the KEFs. As your Onkyo does have HMDI outputs, you can grab a cheap HDMI to Toslink converter like this and then run an optical S/PDIF cable to your KEFs. No electrical connection -> no ground loop anymore.
 
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isomorphZeta

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When all of the audio eqipment had only the 2 pin mains connection (what many of the 1970-80 gear had) then there is no ground loop problem due to the safety earth connection of one (normally then no problem) or more units (problem possible). By the way, with Furman power conditioners there I had a problem due to magnetic hum induction to audio line wires from the coils in the Furman.
Interesting! Any idea where I can read more on this?
 

Pecrobet

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Can you try this for me - can you run a cable from the ground pin by the phono jacks on your avr or alligator clip a cable on the chassis somewhere to a known ground - e.g. your ground rod or probably the chassis of your toaster or fridge - something with a known ground?

I see your AVR and your external amplifier have no ground connections at all. They only use 2 pin live(hot) and neutral connectors. The two of them combined will have a lot of leakage (non hazardous, as eddy currents in their chassis amongst other things) once connected to you guessed it, your kef ls50w's which have 3 pin power cables and a nice ground for all that leakage to rush down.

I.E. get a fkn ground on that AVR chassis and it should all vanish there instead of make its way to the kefs ground, through the sensitive kef input circuitry.

Let me know how that goes
I agree with McFly’s assessment. MUST ground AVR chassis! The importance of solid ground connections for audio components is extremely vital.
 
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