Unknown electrical complication affecting my audio system

[tmtomh]

If the device is humming in one location and not another, then the most likely scenario is that something in the power supply or other circuitry is reacting in some way to the AC feed - or less likely to DC offset from some other source, or even less likely from some other interference or phenomenon - in the OP's location.

DC blockers don't always eliminate DC-induced transformer hum from the AC line, but to my knowledge they almost always reduce it, at least somewhat, if that is indeed the cause.

So in this case I would hypothesize that the cause is not excessive DC in the OP's AC line. But as @solderdude notes, some transformers just hum. I don't know how plausible this is, but perhaps this transformer has become particularly susceptible to DC as it has aged, and perhaps the OP's AC, while within normal parameters, has just a bit more DC offset than in the other location where the device did not exhibit this hum.

Since the device is not just an amp, I'm also wondering if there's a possibility that the mechanical hum might be from some component other than the transformer itself. I had a MiniDSP SHD whose power supply hummed at a low level, albeit at a higher frequency/pitch than an amp transformer typically would. Listening closely with my ear near the top vents of the case, it became clear to me that it was not transformer hum - it was coil whine. They sent me a replacement PSU - a drop-in replacement but clearly a different revision with some different board components and locations - and that one did not exhibit the issue.

I never had the opportunity to test that unit anywhere but my own home, so I don't know if it would have disappeared when plugged into someone else's power. Still, I wonder if there's any possibility that coil whine could be what the OP is hearing?

 

[kyuu]

OMG! This is bigger than my amp!!! but if I understand well the UPS is more a surge protection than suppression.

What?

1) UPSes vary in size.
2) Dunno what you're on about in regards to surge protection versus suppression. Either way, that's a secondary consideration when it comes to UPSes. The primary purpose is to provide a battery backup, of course. But the reason I bring it up is because if you're running off the inverter then you effectively isolated from the mains power. As pointed out, the output of an inverter can vary and isn't always necessarily "higher quality" than the mains, but it will certainly be different. Which is all you're really after, you don't need some device that costs several thousand dollars that outputs some super-high quality sine wave. Most people run off some really gnarly-looking (on a graph) mains power without issue. You just need to solve a particular problem, the "quality" of the incoming AC sine wave is really quite immaterial beyond that.

In order to be always running off the inverter, you have to be using an online, double-conversion type. A line-interactive or standby UPS will just be passing the mains through largely unmolested as long as it's present and doesn't have a problem. However, if you're just looking to troubleshoot any type will work fine. Just run the equipment off the battery (by not having the UPS plugged in) and you will quickly know whether or not your mains is the issue.

But honestly, beyond borrowing one from somewhere for troubleshooting purposes, I don't think a UPS is your solution here. I only brought them up as an alternative to a so-called "power regenerator".

As has been pointed out, if you're serious about troubleshooting this we really need more information about your setup and whatever troubleshooting has already been done, otherwise we're just shooting in the dark here.

 

[Philbo King]

Hi,

I am quite desperate! I live in Germany, a couple of weeks ago I started hearing a subtle buzz from inside the amplifier-pre-DAC I tried everything possible with/out interconnects and fully isolated. I hired an electrician and everything measurable was below the standard regulations, but usually they don't have much idea about audio system and even if they do they need a very sophisticated equipment.
The amp/pre/DAC producers couldn't find any failures and I was recommended to get a DC blocker (hasn't made any difference), the DC offset without the DC blocker though the day <60mv At this point every presumable solution seems to be extremely expensive! any suggestions causes or ways to resolve this?

Thanks all!

Have a competent tech check the filter caps in the units power supply, maybe.

 

[solderdude]

Have a competent tech check the filter caps in the units power supply, maybe.

Tech already looked at it, besides the hum is mechanical from the device itself and not electrical.

 

[Xen]

Thanks for the input!!!

I don't know if the "Stromtank"(exhorbitant price) share the same function as the UPS. I must say that Lampizator and Audionet has an excellent customer service, they don't do just a simple check, and the equipment are tested in a normal environment. One even let it running for few days and no buzz. And also about identifying the probable root cause.

This started in May, and there hasn't been done any installation or changes in the building. I am unaware of the extent to which the neighbors could have any influence on the electric grid and in the apartment.

At the same time I am very concerned that this could cause the audio system to decay.

 

[Sokel]

Motors or LED strips in your grid?
Dimmers at the lights?

 

[DanielT]

A bit far-fetched perhaps, but I can ask since it now seems that the electrical system in your apartment is the cause:
Have you plugged in any electrical gadget and after plugging it in the buzzing problem with your amp/DAC started?
Speaking of far-fetched. Your amp was tested by a professional. They didn't find anything wrong, or hear any buzz. Did they have the same power cord as you have? That there would be something wrong with your power cord to your amp, as I said far-fetched but I'm throwing it out there anyway.

Have you tested the amp in all your outlets in your apartment? You said yes. Same buzz regardless of outlet.

Have you tried unplugging other devices (whatever they are) and then plugging in your buzzing amp in your apartment? I don't remember what you said?

Is it always buzzing or does it happen at specific times of the day? Constantly according to your answer.

You couldn't go to any neighbor in your apartment complex and plug in your amp and hear if it's the same buzz there, you said. Too bad but okay, if that's the case, that's the case.

You've had a professional electrician visit your home, recently in connection with the buzzing problem with your amp, if I understand correctly. He did an inspection of the electrical system in your apartment. He checked, measured and did everything a professional electrician does and he found nothing. That's right, isn't it?
I'm just repeating the conditions in your case.

Do you have grounded outlets in your apartment? In that case, did the electrician check to make sure the grounding was working properly?

Anyway. Now I'm out of ideas. Someone else will have to think.

 

[RandomEar]

Hi @Xen . Could you give us a bit more info on the devices and how you tested them? What models do you use? Are they all affected?

It would also be nice to have one post with a concise description of the problem and every diagnostic step you tried. Right now, this is a bit convoluted.

I understand this started in may and you had your electrical installation inspected and send the devices to the manufacturer for a check up, correct?
I also understand that you turned off all breakers except for those of your listening room and the buzz still continued. And you also tried different outlets in your flat, correct?

 

[DanielT]

Motors or LED strips in your grid?
Dimmers at the lights?

LED strips that are powered via a transformer. Placed near an amp. That in itself can create a buzz. I actually experienced that myself last winter in my apartment when I put up more lights, during the darkest days of the year. The LED strip was very close to my amp, clumsy of me to place it like that.
In any case, after I moved the amp a bit away from the LED strip, the problem disappeared.

 

[Sokel]

LED strips that are powered via a transformer. Placed near an amp. That in itself can create a buzz. I actually experienced that myself last winter in my apartment when I put up more lights, during the darkest days of the year. The LED strip was very close to my amp, clumsy of me to place it like that.
In any case, after I moved the amp a bit away from the LED strip, the problem disappeared.

In this house I have dedicated lines for the toys. No interference at all by the rest of the stuff.

In my other, older house there was a series of issues.

Pushing the (non-LED) light dimmers to ON (not rotating them) could sometimes stop a DAC.
And boi, LEDs, that's a chapter on its own.

Measuring gear with LED strips on and you could see the low registers (lower than 10Hz) jumping around nice 20dB jumps!
While DC was zero at the outputs, it reminded a wrong op-amp in a circuit or one that has gone bad.

Dimming them made things worst.
Fun fact, I choose very well regarded LEDs and their PSUs after horror stories even about fires.

If I was in a shared outlet grid, LEDs and LED strips should be banned for life!

 

[DanielT]

In this house I have dedicated lines for the toys. No interference at all by the rest of the stuff.

In my other, older house there was a series of issues.

Pushing the (non-LED) light dimmers to ON (not rotating them) could sometimes stop a DAC.
And boi, LEDs, that's a chapter on its own.

Measuring gear with LED strips on and you could see the low registers (lower than 10Hz) jumping around nice 20dB jumps!
While DC was zero at the outputs, it reminded a wrong op-amp in a circuit or one that has gone bad.

Dimming them made things worst.
Fun fact, I choose very well regarded LEDs and their PSUs after horror stories even about fires.

If I was in a shared outlet grid, LEDs and LED strips should be banned for life!

I also changed the power outlet for the LED strip. In the same two outlets was the power cord to the amp.


That may have had something to do with it. Cheap crappy LED strip with an equally crappy transformer for them. By the way it already had an audible buzzing sound when new that LED trafo. Damn, I think I'll throw that cheap LED strip away and buy a better one. Stinginess belies wisdom.
Besides, I'll be running a LED strip out on the balcony railing this winter and there won't be any amplifier on the snowy balcony. That much I know.
(plus it will then be plugged into an outlet where I don't plug in my Hifi equipment)

If I was in a shared outlet grid, LEDs and LED strips should be banned for life!
You have a point, but it's nice to have extra light in the winter when it gets dark. Especially up here in the north when the sun doesn't shine for many hours a day on the darkest days.

 

[Xen]

The main issue is that the buzz is coming only from inside, of every device that have a transformer of certain size. I isolate the apartment rooms by switching off the breakers one by one and the issue persist. The DAC and pre are manageable to move around to check independently under different setups, I tried to rule out the source of the problem.

I was told that there are some disruptions which are very hard to measure, even with the usual sophisticated equipment. A normal electrician went through approx 16 different measurements, there where just a couple that needed a special test device. A highly specialized technician with a dedicated testing meters, certainly could find the irregularities and then practically I am limited to what is seem a very expensive device, without sacrificing audio quality.

At this point I am trying to diminish any electrical disruption happening upstream the grid, probably caused by a neighbor. Anyhow it looks like is very tricky problem not easy to resolve.

 

[Pareto Pragmatic]

Have you gotten anything electrical recently. Anything new plugged in?

It's most likely something going bad or starting to in the unit. If it were me, I would open the thing up and look for any loose connections or suspect solder joints. Testing individual components is not something I would do, but a quick look might give you some idea.

Generally speaking, if you pay for electricity directly (there is a meter for your unit) the building will be wired differently than if it is included in the rent. Even if every unit is separate, things like fire detectors that are wired in will share load between building areas.

At this point I am trying to diminish any electrical disruption happening upstream the grid, probably caused by a neighbor.

Can you take the unit to another place, work, family member, friend? Plug it in there. If the problem is still there, unit. If not, electrical supply.

My electrical problems are a bit less subtle, given a 100 year old house. So it could be worse!

 

[RandomEar]

The main issue is that the buzz is coming only from inside, of every device that have a transformer of certain size. I isolate the apartment rooms by switching off the breakers one by one and the issue persist. The DAC and pre are manageable to move around to check independently under different setups, I tried to rule out the source of the problem.

I was told that there are some disruptions which are very hard to measure, even with the usual sophisticated equipment. A normal electrician went through approx 16 different measurements, there where just a couple that needed a special test device. A highly specialized technician with a dedicated testing meters, certainly could find the irregularities and then practically I am limited to what is seem a very expensive device, without sacrificing audio quality.

At this point I am trying to diminish any electrical disruption happening upstream the grid, probably caused by a neighbor. Anyhow it looks like is very tricky problem not easy to resolve.

Again: Please tell us which devices are affected and what exactly you already tested.

It would also be helpful to get an FFT of the noise, for example using the Spectroid app. Place your phone on the noise source, leave the app running for 30 seconds, hit pause and make a screenshot.

 

[Palmer]

Again: Please tell us which devices are affected and what exactly you already tested.

It would also be helpful to get an FFT of the noise, for example using the Spectroid app. Place your phone on the noise source, leave the app running for 30 seconds, hit pause and make a screenshot.

@Xen posted Lampi/audionet/gryphon - assuming this is about a DAC of the Lampizator lineup, there's 11 of them, 10 if we skip the most recent addition.
Furthermore this is a weird sort of description of the system involved, Audionet makes different products, so does Gryphon. All of this is rather expensive, too - so the whole thing about being desperate, well - I have a very hard time with it.
I rest my case.

 

[Xen]

Again: Please tell us which devices are affected and what exactly you already tested.

It would also be helpful to get an FFT of the noise, for example using the Spectroid app. Place your phone on the noise source, leave the app running for 30 seconds, hit pause and make a screenshot.

I will try the app and see if the phone mic pick something As has previously been mentioned, DAC-2xAmp-Pre and a separate device which just down convert AC to DC with four transformers.

The test is simple I just take any equipment plug it in an apartment outlet get very close and check if there is a buzz!

I have been checking for an outlet within the building but couldn't find any.

After having ruled out many possible sources, as have been said the cause is in the main electrical system. This started two months ago and I haven't done any changes in the apartment.

Certainly for what I believe there are some factors out of my reach. Any changes or wrong installations done by a neighbor itself.

 

[Xen]

@Xen posted Lampi/audionet/gryphon - assuming this is about a DAC of the Lampizator lineup, there's 11 of them, 10 if we skip the most recent addition.
Furthermore this is a weird sort of description of the system involved, Audionet makes different products, so does Gryphon. All of this is rather expensive, too - so the whole thing about being desperate, well - I have a very hard time with it.
I rest my case.

This is more complex than what I thought and trying to pinpoint exactly the cause to solve it could be very costly.
Nevertheless the causes are not related to the audio system per se!

Many thanks for the comments!!!

 

[solderdude]

If it is something in the building itself (extremely unlikely) using any other socket in the same building is pointless.
For instance when installed solar panels on the roof that have converters that don't produce a 'nice' mains voltage then the whole building would have this.

Pick up the device that hums.
Visit a friend or family member and take it along with you.
Plug it in the wall socket there.
Switch it on an leave it on for an hour or so.
Hear the same hum... problem is in the device.
Awfully quiet ... not the device.

Could also be you either started noticing it hums(and any other device with a transformer) or the transformer in the device simply is humming a bit louder than before.

You certainly don't have to worry about safety or longevity issues for connected gear assuming the mains voltage isn't too high. As guys already checked the mains voltage that is a very unlikely scenario (over-voltage).

 

[SSS]

This is more complex than what I thought and trying to pinpoint exactly the cause to solve it could be very costly.
Nevertheless the causes are not related to the audio system per se!

Many thanks for the comments!!!

If the buzz is acoustical (not electrical in the audio signal chain) from inside the amp/pre/dac then the unit has either a defect which makes one or more of components create the buzz. Or it is just a bad component like mains transformer or a coil. Even a capacitor can buzz which is very seldom. Let the amp checked by an experienced audio/electronics technichian, not by an electrician installer. I doubt that the buzz is induced from the mains line outside. Germany in genereal has a good mains power supply grid.

 

[DanielT]

Pick up the device that hums.
Visit a friend or family member and take it along with you.
Plug it in the wall socket there.
Switch it on an leave it on for an hour or so.
Hear the same hum... problem is in the device.
Awfully quiet ... not the device.

I don't know if the "Stromtank"(exhorbitant price) share the same function as the UPS. I must say that Lampizator and Audionet has an excellent customer service, they don't do just a simple check, and the equipment are tested in a normal environment. One even let it running for few days and no buzz. And also about identifying the probable root cause.

Just so I understand. You @Xen are talking about your device now, which buzzes/hum in your apartment which doesn't buzz/hum at Lampizator and Audionet when they tested. Is that correct?
How do you know if they don't just say there's no buzz/hum? I mean it's subjective. They may not have experienced it the way you do. So I think you should follow Solderdude's advice.