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Amp started humming after setting up Wifi network- coincidence?


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Hi

 

I recently ventured into the world of streaming over wifi.

 

The next day, my hitherto well behaved integrated amplifier started intermittently humming/buzzing from inside the unit itself- i.e. it's not coming through the audio/speakers  but from components in the actual amp.

 

If I was more knowledgeable I might guess it sounds like transistor transformer noise/buzz. It comes and goes.

 

I unplugged the RCA connecting the amp to the digital player (SBT), and also turned the server off, but that seems to make no difference. We've had Netflix etc streaming in the same room for ages (no connections to the amplifier) and this never happened.

 

Just a coincidence that the amp started playing up at this time?

Edited by ericd
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3 hours ago, ericd said:

Hi

 

I recently ventured into the world of streaming over wifi.

 

Aah well - you ventured over the line, into the dark side ... and it bit you in the bum!  :lol:

 

3 hours ago, ericd said:

The next day, my hitherto well behaved integrated amplifier started intermittently humming/buzzing from inside the unit itself- i.e. it's not coming through the audio/speakers  but from components in the actual amp.

 

That sounds like the transformer in your integrated amp buzzing - which they can do if DC is on your mains.

 

3 hours ago, ericd said:

If I was more knowledgeable I might guess it sounds like transistor transformer noise/buzz. It comes and goes.

 

'Comes and goes ' is a problem.  :(

 

3 hours ago, ericd said:

I unplugged the RCA connecting the amp to the digital player (SBT), and also turned the server off, but that seems to make no difference.

 

Just a coincidence that the amp started playing up at this time?

 

I was going to suggest that maybe the power supply in the SBT (which will be a SMPS) was the culprit - however, as you've turned it off and your integrated amp still buzzes ... it would seem not.

 

Unless "turning it off " simply puts it into 'Sleep' mode - did you turn it off at the wall socket?

 

Maybe your neighbour has done something which now puts DC onto your mains (so you implementing streaming-over-wifi is irrelevant)?

 

Would you like me to bring over (now that Stage 3 lockdown has been lifted) one of my DC blockers, so we can see whether this solves your buzzing problem?  Or, of course, you can come over here (Richmond) and pick it up!

 

Andy

 

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Thanks Andy

Very nice of you to offer. I will explore the issue a bit further and get back to you.

 

I knew something would go wrong when I tried to set up streaming. Even if the amp issue is technically unrelated to the wifi, I'm cursed!

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  • 4 weeks later...

I just discovered by accident that the hum happens when the panel heater is on. It's in the same room but not plugged in to the same powerboard or powerpoint. Does this either support or disprove the DC theory, or suggest something else entirely?

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10 hours ago, ericd said:

I just discovered by accident that the hum happens when the panel heater is on. It's in the same room but not plugged in to the same powerboard or powerpoint. Does this either support or disprove the DC theory, or suggest something else entirely?

DC seems unlikely. But depending on how the heater controls its output, the heater could be creating EMI on that power circuit. I'm thinking things like PWM or Triac switching. I'd have though a simple heater would just run straight AC to the heating element and switch it either on or off via a thermostat, rather than try and modulate the power like s dimmer or motor speed controller.

You'd reckon a heater that could be radiating that sort of interference/ripple/noise wouldn't pass AU electrical approval though.

Can you share the heater brand and model, so we can see if there's information about its design available?

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47 minutes ago, ericd said:

It's a Noirot 2400W panel heater- the  model # is 7358-8.

Noirot 7358-7T is listed on the Choice website in an article titled 5 Heaters Not To Buy.

"Offering only borderline heating performance, this heater is more expensive than many of the top-scoring heaters in our review. It only rated as 'OK' for comparative energy efficiency, has no cord storage, and our testers found that it wasn't very easy to move."

 

That'll be the same basic model, just with timer/no timer variant or similar.

Nothing about poor electrical behaviour though.

 

I'd take it back, cite the Choice "don't buy" listing and combine that with the electrical issues you're having, I'd say you'd stand a good chance of getting your money back.

 

I can PM you the Choice recommendations of what to get to replace it if you want.

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Thanks Peter, but it's well past return date. Despite that review, it's worked perfectly well for me for over 10 years!

 

I'm assuming though that none of those issues in the review explain why the heater causes the buzzing amp?

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11 minutes ago, ericd said:

...it's well past return date.

I'm assuming though that none of those issues in the review explain why the heater causes the buzzing amp?

Apparently it has a lifetime warranty, so take it back.

No, the bad review doesn't mention it causing electrical problems.

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The hum is very likely coming from the EMI created by the triac in the electronic thermostat on the heater. I have a different thermostat that does the same thing to AM radio, but not to other sources.

Edited by Stevesie
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I have a similar issue when the dryer is on in the laundry I can hear an occasional pop (through the speakers though via the power amp i think) when the dryer alters a cycle (it's programming is to start/stop).

 

Turn the dryer off, no problem. 

 

 

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It could be DC offset on the line. Sounds to me like it is. I had an issue with that once.

there's a thread here: https://www.stereo.net.au/forums/topic/239149-buzzing-toroidal-transformer/

 

Here's one perspective on it:

https://www.pooraudiophile.com/2015/03/how-to-fix-dc-offset-and-transformer.html

 

 

The symptom of that IS  the amp transformer humming. And yes, a specific device in the house like a heater, lamp, printer, fridge, etc. Can cause it.

There are relatively inexpensive DC blockers on the market This one works:

https://avahifi.com/products/humdinger-dc-line-blocker?_pos=1&_sid=016edc167&_ss=r

 

There's also this, which is Australian, but many times more expensive.

 

Some power conditioning devices also block DC. It  will say so in the product description if it does.

 

If you want to be sure that's the cause is DC offset, get yourself some time alone in the house.  Unplug everything in the house. Also turn off all the breakers in your electric board except the one powering the amp. Turn on amp? Hum? then it isn't the heater. No hum.:Turn on breaker for, heater: hum?   no? and then heater itself: hum? yes, it's the heater. You can turn on the other breakers  and devices one by one to see if a specific item is causing the DC on the line.

 

You can also have DC coming into your home from something outside the home, which is why I wrote the procedure above. If you thoroughly do the procedure above and still can't find an in house source, you may have DC coming in from a neighbor or some other source outside the home that's on your part of the grid.

 

Of course, the first thing you should do is check that the screws attaching the transformer to the amp aren't loose....

 

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3 hours ago, firedog said:

Of course, the first thing you should do is check that the screws attaching the transformer to the amp aren't loose....

Thanks @firedog. Pretty sure it's not loose screws as the correlation between heater on/amp buzz and heater off/no amp buzz is 100%.

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On 18/05/2020 at 2:43 PM, ericd said:

Hi

 

I recently ventured into the world of streaming over wifi.

 

The next day, my hitherto well behaved integrated amplifier started intermittently humming/buzzing from inside the unit itself- i.e. it's not coming through the audio/speakers  but from components in the actual amp.

 

If I was more knowledgeable I might guess it sounds like transistor transformer noise/buzz. It comes and goes.

 

I unplugged the RCA connecting the amp to the digital player (SBT), and also turned the server off, but that seems to make no difference. We've had Netflix etc streaming in the same room for ages (no connections to the amplifier) and this never happened.

 

Just a coincidence that the amp started playing up at this time?

But you also said it's not coming through the audio, as above. So the buzz/humm is mechanical. So @firedog suggestion has a lot of validity.

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