AV Receiver hum in new house
Discussion
I've just moved into a new rented house. Getting unpacked and everything set up and have found a nightmare problem.
I have a little old Sony stereo and a quite new Pioneer AV Receiver.
Both have a quite audible hum from the units themselves. The Sony does it when connected to the mains, regardless of whether the stereo itself is switched on. The Pioneer receiver is silent when connected to the mains, but hums/buzzes when you switch it on.
Both make the noise with just the mains lead connected (ie; no speakers or other equipment.) They were both silent in my old flat. I'm pretty sure they are buzzing at 50Hz (if I play a 50Hz test tone on my phone, it sounds the same.) It's not incredibly loud, but can be heard from 6 feet away on both units. Sort of thing a friend probably wouldn't notice if they came over, but once heard cannot be un-heard.
I've started searching the web and going down the rabbit hole of 'DC offset'. I've tried switching off all the circuits in the house other than the 'living room sockets' circuit that the equipment is connected to. I've then tried moving the stereo to a different 'bedroom sockets' circuit and just having that live (everything else off). The issue persists regardless. So it seems like it's not being caused by something in the house.
Next step seems to be some sort of 'mains filter' - but you quickly seem to delve towards stuff which could feature in the "More 'Audiophile' bullsh*t" thread. I don't want a mains filter to 'widen my sound stage'. I just want the b
d buzzing to go away.
I've found a couple of things like this https://ifi-audio.com/products/dc-blocker/ which don't seem to claim any audiophile nonsense. But at £129 on Amazon I'm hoping there may be more 'DIY' options.
Help please!?
I have a little old Sony stereo and a quite new Pioneer AV Receiver.
Both have a quite audible hum from the units themselves. The Sony does it when connected to the mains, regardless of whether the stereo itself is switched on. The Pioneer receiver is silent when connected to the mains, but hums/buzzes when you switch it on.
Both make the noise with just the mains lead connected (ie; no speakers or other equipment.) They were both silent in my old flat. I'm pretty sure they are buzzing at 50Hz (if I play a 50Hz test tone on my phone, it sounds the same.) It's not incredibly loud, but can be heard from 6 feet away on both units. Sort of thing a friend probably wouldn't notice if they came over, but once heard cannot be un-heard.
I've started searching the web and going down the rabbit hole of 'DC offset'. I've tried switching off all the circuits in the house other than the 'living room sockets' circuit that the equipment is connected to. I've then tried moving the stereo to a different 'bedroom sockets' circuit and just having that live (everything else off). The issue persists regardless. So it seems like it's not being caused by something in the house.
Next step seems to be some sort of 'mains filter' - but you quickly seem to delve towards stuff which could feature in the "More 'Audiophile' bullsh*t" thread. I don't want a mains filter to 'widen my sound stage'. I just want the b
d buzzing to go away.I've found a couple of things like this https://ifi-audio.com/products/dc-blocker/ which don't seem to claim any audiophile nonsense. But at £129 on Amazon I'm hoping there may be more 'DIY' options.
Help please!?
Check your mains voltage. A lot of kit is rated for 220 or 230 volts supply. Tolerances in the UK allow up to 253 volts. That’s enough to get the transformer humming on a lot of kit. I’ve had this issue in the past; getting your electricity network provider to lower the supply voltage can be challenging.
Magnum 475 said:
Check your mains voltage. A lot of kit is rated for 220 or 230 volts supply. Tolerances in the UK allow up to 253 volts. That’s enough to get the transformer humming on a lot of kit. I’ve had this issue in the past; getting your electricity network provider to lower the supply voltage can be challenging.
Thanks, that's interesting/annoying! The Pioneer is rated for "AC 220-240 V, 50/60 Hz" and the Sony just has "230V" on the back.
This is going to be painful
No energy company even wants me as a customer at the moment - all their sign up pages are just a polite version of 'go away'.I'm signing up with E.ON because as the incumbent supplier they've got no choice (just like me!)
What happens if you turn off everything in the house?
I had a similar problem... I replaced my amps and the new ones had a similar issue; it was always there but did vary in volume. This would be with everything else in the house unplugged, all other circuits turned off etc.
I did buy some cheapish DC blockers after a chat with an engineer at Musical Fidelity and they helped but it was still there. I got used to it.
A couple of years later I realised my problem had gone, and this coincided with new neighbours next door!
I had a similar problem... I replaced my amps and the new ones had a similar issue; it was always there but did vary in volume. This would be with everything else in the house unplugged, all other circuits turned off etc.
I did buy some cheapish DC blockers after a chat with an engineer at Musical Fidelity and they helped but it was still there. I got used to it.
A couple of years later I realised my problem had gone, and this coincided with new neighbours next door!
UpTheIron said:
What happens if you turn off everything in the house?
It makes no difference unfortunately. As above, I've tried isolating individual circuits and the same result on all of them.I've actually ordered a DC blocker too before I saw Magnums response. Coming from Amazon so I can return it if it does/doesn't make a difference.
There are a few things you can look at.
DC offset is worth a look. If you have a decent multimeter, you should be able to measure DC volts directly on the mains.
I'm not sure what sort of limit is reasonable though.
AC voltage level, I'd expect decent audio equipment to cope with a few extra volts. But a Variac can reduce the volts, you might find an isolation transformer with a slight step down, which would also deal with the DC or at least move the problem into another box.
It is possible the problem is impulse noise on the mains, you can try an inline filter or even transient absorber as used sometimes to protect computers from surges.
It's possible some other equipment on the circuit is generating lots of harmonics, try switching everything off. Personally I have an oscilloscope or two, so I'd be looking at the mains waveform. IS there PV solar nearby? meaty car chargers?
Try taking the hifi to another building, it's possible the kit's been dropped while moving/it always did it but you didn't notice/whatever.
It's semi-plausible that having no inputs connected doesn't help. Rule that out.
Measure the Neutral-Earth AC and DC voltages. Is the kit double insulated or mains earthed?
DC offset is worth a look. If you have a decent multimeter, you should be able to measure DC volts directly on the mains.
I'm not sure what sort of limit is reasonable though.
AC voltage level, I'd expect decent audio equipment to cope with a few extra volts. But a Variac can reduce the volts, you might find an isolation transformer with a slight step down, which would also deal with the DC or at least move the problem into another box.
It is possible the problem is impulse noise on the mains, you can try an inline filter or even transient absorber as used sometimes to protect computers from surges.
It's possible some other equipment on the circuit is generating lots of harmonics, try switching everything off. Personally I have an oscilloscope or two, so I'd be looking at the mains waveform. IS there PV solar nearby? meaty car chargers?
Try taking the hifi to another building, it's possible the kit's been dropped while moving/it always did it but you didn't notice/whatever.
It's semi-plausible that having no inputs connected doesn't help. Rule that out.
Measure the Neutral-Earth AC and DC voltages. Is the kit double insulated or mains earthed?
There are a few things you can look at.
DC offset is worth a look. If you have a decent multimeter, you should be able to measure DC volts directly on the mains.
I'm not sure what sort of limit is reasonable though.
AC voltage level, I'd expect decent audio equipment to cope with a few extra volts. But a Variac can reduce the volts, you might find an isolation transformer with a slight step down, which would also deal with the DC or at least move the problem into another box.
It is possible the problem is impulse noise on the mains, you can try an inline filter or even transient absorber as used sometimes to protect computers from surges.
It's possible some other equipment on the circuit is generating lots of harmonics, try switching everything off. Personally I have an oscilloscope or two, so I'd be looking at the mains waveform. IS there PV solar nearby? meaty car chargers?
Try taking the hifi to another building, it's possible the kit's been dropped while moving/it always did it but you didn't notice/whatever.
It's semi-plausible that having no inputs connected doesn't help. Rule that out.
Measure the Neutral-Earth AC and DC voltages. Is the kit double insulated or mains earthed?
DC offset is worth a look. If you have a decent multimeter, you should be able to measure DC volts directly on the mains.
I'm not sure what sort of limit is reasonable though.
AC voltage level, I'd expect decent audio equipment to cope with a few extra volts. But a Variac can reduce the volts, you might find an isolation transformer with a slight step down, which would also deal with the DC or at least move the problem into another box.
It is possible the problem is impulse noise on the mains, you can try an inline filter or even transient absorber as used sometimes to protect computers from surges.
It's possible some other equipment on the circuit is generating lots of harmonics, try switching everything off. Personally I have an oscilloscope or two, so I'd be looking at the mains waveform. IS there PV solar nearby? meaty car chargers?
Try taking the hifi to another building, it's possible the kit's been dropped while moving/it always did it but you didn't notice/whatever.
It's semi-plausible that having no inputs connected doesn't help. Rule that out.
Measure the Neutral-Earth AC and DC voltages. Is the kit double insulated or mains earthed?
OutInTheShed said:
There are a few things you can look at.
DC offset is worth a look. If you have a decent multimeter, you should be able to measure DC volts directly on the mains.
I'm not sure what sort of limit is reasonable though.
DC offset is worth a look. If you have a decent multimeter, you should be able to measure DC volts directly on the mains.
I'm not sure what sort of limit is reasonable though.
mgv8 said:
I have never looked at a DC blocker. The reports in the most part seem to like the effect. How do you test for DC on the line to see if you need this?
Thanks for these suggestions. I started to look into this and it seems... complicated. From reading a few forum posts it seems more complicated than jamming multimeter probes into the wall outlet. So I don't know what good/bad would look like, or how to measure it properly! (Incidentally, I did just jam the multimeter probes into the wall outlet and I see -0.066V DC. But I get a negative value regardless of which way I touch the probes. And it's also showing 50Hz signal on the DC. So I think it's possibly just an artefact/issue with the testing multimeter, rather than an actual signal/current on the line.)OutInTheShed said:
AC voltage level, I'd expect decent audio equipment to cope with a few extra volts. But a Variac can reduce the volts, you might find an isolation transformer with a slight step down, which would also deal with the DC or at least move the problem into another box.
It is possible the problem is impulse noise on the mains, you can try an inline filter or even transient absorber as used sometimes to protect computers from surges.
This arrived from Amazon on Saturday https://www.audiolab.co.uk/dc-block/ It claims to block DC and have EMI/RFI filtersIt is possible the problem is impulse noise on the mains, you can try an inline filter or even transient absorber as used sometimes to protect computers from surges.
(And the product description/website seemed the least 'snake oily' of the ones I looked at.) And it makes no difference whatsoever. I tried it on the Sony and the Pioneer. Identical noise as being plugged directly to the mains.
OutInTheShed said:
Try taking the hifi to another building, it's possible the kit's been dropped while moving/it always did it but you didn't notice/whatever.
It's semi-plausible that having no inputs connected doesn't help. Rule that out.
Ah, that's interesting that no inputs could be the issue in itself. The little Sony only has RCA inputs, and it does the same regardless of RCA leads hooked up. The Pioneer AMP is all digital. I've only got the TV connected over HDMI ARC. It's the same without or without being connected.It's semi-plausible that having no inputs connected doesn't help. Rule that out.
I'm almost certain it's not the equipment itself. I moved myself and packed everything myself, and it's happening with two different systems. If it was just the one then I'd definitely be getting something else to check, but it seems super unlikely that two systems have 'failed' in the same way during the move.
OutInTheShed said:
It's possible some other equipment on the circuit is generating lots of harmonics, try switching everything off. Personally I have an oscilloscope or two, so I'd be looking at the mains waveform. IS there PV solar nearby? meaty car chargers?
Yep, neighbours have car chargers and I'm sure there's be solar on the street.My cheapy "oscilloscope" is hard to get good resolution (and I have no idea what I'm doing!) but to my layman's eyes the AC looks like it is 'clipping'.
The two crappy photos are at difference scales on the meter.
Compared to a better sinewave I get by playing a 50Hz test tone from the headphone jack on my phone..
OutInTheShed said:
Measure the Neutral-Earth AC and DC voltages. Is the kit double insulated or mains earthed?
Both. Pioneer is double insulated (two pin plug) and the Sony appears to have an earth pin.Those mains waveforms don't look good.
It looks like a high harmonic content, however it could be an artefact of the scope/meter.
While it's consistent with 'clipping, it's maybe more like to be an effect of non linear loads on the network.
It's a DNO issue not an energy retailer issue, but it may be that your retailer is the contact to get the DNO to take a look.
In the meantime, your only real ways forward are audio equipment with switchmode power supplies instead of great heavy transformers, or some sort of mains conditioning box which certain high end audiophile people might sell. I'm not familiar with any 'retail' versions of these gadgets.
Personally, I'd avoid using transformer based equipment when it starts making a noise, it can't be doing it any good.
It can be serious, this kind of thing has been linked to things catching fire.
It looks like a high harmonic content, however it could be an artefact of the scope/meter.
While it's consistent with 'clipping, it's maybe more like to be an effect of non linear loads on the network.
It's a DNO issue not an energy retailer issue, but it may be that your retailer is the contact to get the DNO to take a look.
In the meantime, your only real ways forward are audio equipment with switchmode power supplies instead of great heavy transformers, or some sort of mains conditioning box which certain high end audiophile people might sell. I'm not familiar with any 'retail' versions of these gadgets.
Personally, I'd avoid using transformer based equipment when it starts making a noise, it can't be doing it any good.
It can be serious, this kind of thing has been linked to things catching fire.
OutInTheShed said:
Those mains waveforms don't look good.
It looks like a high harmonic content, however it could be an artefact of the scope/meter.
While it's consistent with 'clipping, it's maybe more like to be an effect of non linear loads on the network.
It's a DNO issue not an energy retailer issue, but it may be that your retailer is the contact to get the DNO to take a look.
In the meantime, your only real ways forward are audio equipment with switchmode power supplies instead of great heavy transformers, or some sort of mains conditioning box which certain high end audiophile people might sell. I'm not familiar with any 'retail' versions of these gadgets.
Personally, I'd avoid using transformer based equipment when it starts making a noise, it can't be doing it any good.
It can be serious, this kind of thing has been linked to things catching fire.
That's interesting thanks, if not exactly good news!It looks like a high harmonic content, however it could be an artefact of the scope/meter.
While it's consistent with 'clipping, it's maybe more like to be an effect of non linear loads on the network.
It's a DNO issue not an energy retailer issue, but it may be that your retailer is the contact to get the DNO to take a look.
In the meantime, your only real ways forward are audio equipment with switchmode power supplies instead of great heavy transformers, or some sort of mains conditioning box which certain high end audiophile people might sell. I'm not familiar with any 'retail' versions of these gadgets.
Personally, I'd avoid using transformer based equipment when it starts making a noise, it can't be doing it any good.
It can be serious, this kind of thing has been linked to things catching fire.
Once I actually have an energy account set up properly I'll see if I can get them investigate.
Take a look at this thread - https://www.eevblog.com/forum/projects/show-us-you...
hab1966 said:
Take a look at this thread - https://www.eevblog.com/forum/projects/show-us-you...
Ah, that's really interesting thanks. So 'they all do that sir'.Gassing Station | Home Cinema & Hi-Fi | Top of Page | What's New | My Stuff