Unknown electrical complication affecting my audio system

[Xen]

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!

 

[voodooless]

A DC blocker does not influence your DC offset on any audio output. It only blocks the DC on the AC lines. This DC can cause buzzing when it goes through a sizable transformer, like in some amps. So, was the 0,6 mV measured at the AC lines?

 

[Xen]

The DC offset from the outlet<60mv the buzz is only from inside the equipment. A couple of weeks ago, was pure silence

 

[ppataki]

See this:

P

'DC blocker tryout'

Oct 7, 2024

I have a 1500VA toroidal isolation transformer - my whole audio-video system is connected to it.
Pretty often I hear a quite loud buzz coming from the isolation transformer which might be caused by some DC component that is fed from my solar panels' inverter unit.
After discussing with my brother-in-law who is a trained electrician I have decided to try a DC blocker - mainly just for fun to see/hear if it would do anything with the buzz from the isolation transformer

I have ordered this unit - once it arrives I will share my experience here

I am not expecting any...

• ppataki
• Replies: 30
• Forum: Audio Power Product Reviews and Discussion

• 

 

[DanielT]

The DC offset from the outlet<60mv the buzz is only from inside the equipment. A couple of weeks ago, was pure silence

What do you mean by : ....the buzz is only from inside the equipment
Don't you hear this buzz in your speakers/headphones?

What amplifier-pre-DAC do you have? Brand and model?

Edit:
Speaking of buzzing noise from the amplifier itself. If this is the same for you, I don't know of course, but this is how it was for me. Buzzing transformers in old amplifiers. In one case, the buzzing disappeared by dampening the vibrations by placing a cut-out rubber cloth between the transformer and the chassis plus really tightening the screws that held the transformer in place. With another amp, that measure did not help.

 

[Cbdb2]

Sounds like a bad component. Can you open it up and hear exactly where the buzz is coming from?

 

[Xen]

Even if nothing is connected just the power cord there is a subtle buzz. I also have a small device with transformer inside and hear the typical buzzing sound from the transformer when I get close to it. Is in the power grid of the apartment. The DC offset before the isotek blocker is <60mv which is very low! Lampi/audionet/gryphon

 

[DanielT]

I hired an electrician and everything measurable was below the standard regulations, .....

Is in the power grid of the apartment.

Are you sure? Have you tested , plugged in your amp and your other little buzzing thing anywhere else than in your apartment?

Even if nothing is connected just the power cord there is a subtle buzz. I also have a small device with transformer inside and hear the typical buzzing sound from the transformer when I get close to it.

See #5. If not that, you or a repairman need to troubleshoot.

You can probably get some advice here from people more knowledgeable about electronics than me, if they know what kind of amp it is. That if you have the ability to service and repair the amp if necessary? Otherwise, take it to a repair shop, if you think it's worth paying for an overhaul.

 

[Xen]

yes! I believe there most be something tricky to resolve, unable to be identified by usual electrical check up to fulfill the standards regulations. I have been kicking my head trying to find out what cause this.

Thanks!!!

 

[DanielT]

yes! I believe there most be something tricky to resolve, unable to be identified by usual electrical check up to fulfill the standards regulations. I have been kicking my head trying to find out what cause this.

Thanks!!!

Aha, so it's localized to your specific apartment.Then there is not (maybe not) anything wrong with the amplifier. That is if it does not buzz in other places than in your apartment. However, something may have happened to it after all because you have not had this problem before. Or, see below:
In your apartment complex. Do you have the opportunity to plug your buzzing amp into a neighbor's apartment's electrical outlet? Test if it sounds the same then as in your apartment.

Have you tested the amp in all your outlets in your apartment?
Have you tried unplugging other devices (whatever they are) and then plugging in your buzzing amp in your apartment?
Is it always buzzing or does it happen at specific times of the day?

 

[Xen]

Aha, so it's localized to your specific apartment.Then there is not (maybe not) anything wrong with the amplifier. That is if it does not buzz in other places than in your apartment. However, something may have happened to it after all because you have not had this problem before. Or, see below:
In your apartment complex. Do you have the opportunity to plug your buzzing amp into a neighbor's apartment's electrical outlet? Test if it sounds the same then as in your apartment.

Have you tested the amp in all your outlets in your apartment?
Have you tried unplugging other devices (whatever they are) and then plugging in your buzzing amp in your apartment?
Is it always buzzing or does it happen at specific times of the day?

thanks for answering!
Germany is not like you can friendly walk in your neighbors apartments! I switched off all the beakers isolating a room with an outlet (checked also in different outlets) the buzz is stable regardless of the time. The buzz is also noticeable a very close distance from the amp/pre or DAC!

I am also concerned that this could decay with the use. I have been recommended a current regenerator, a good one with enough capacity for a class a amplifier+ the system cost a fortune!

 

[kyuu]

If the DC blocker is not resolving the buzzing, then likely you need to open up the device and address the buzzing transformer (transformers vibrate to an extent under normal operation). It seems likely that either the bolts holding it down have come loose, or some other bit meant to isolate the buzzing from the chassis has failed in some way. You may need to replace/add rubber washers or the like. If you're not comfortable with that, find an electronics repair shop who can look at it for you.

This is almost certainly not an electrical issue. Power regenerators are basically a scam. It's not that they don't do anything, but that what they do isn't necessary or useful in general. If you really want to isolate your equipment from the grid, a battery and inverter system (i.e. UPS) can do it for less than the fortune they charge for those (because they are purchased by gullible audiophiles typically, therefore more expensive than necessary).

 

[Xen]

If the DC blocker is not resolving the buzzing, then likely you need to open up the device and address the buzzing transformer (transformers vibrate to an extent under normal operation). It seems likely that either the bolts holding it down have come loose, or some other bit meant to isolate the buzzing from the chassis has failed in some way. You may need to replace/add rubber washers or the like. If you're not comfortable with that, find an electronics repair shop who can look at it for you.

This is almost certainly not an electrical issue. Power regenerators are basically a scam. It's not that they don't do anything, but that what they do isn't necessary or useful in general. If you really want to isolate your equipment from the grid, a battery and inverter system (i.e. UPS) can do it for less than the fortune they charge for those (because they are purchased by gullible audiophiles typically, therefore more expensive than necessary).

There has been 2xamp, pre and a DAC tested at home all with exactly the same issue. I just received the pre and the DAC from the manufacturers, after stress test and sensitive measurements and no problems, only in the apartment. This are quite new equipments, under five years old. Also mechanical isolation has been ruled out.

It's something in the grid complicated to analyze and to measure, also the neighbors doesn't have any real power hungry appliances, just as usual, nevertheless I am unaware of any electrical installations by themselves. I wanted to practically isolate the apartment but the grid is shared in the building and there haven't been any changes since the issue started.

What exactly is a UPS???

 

[kyuu]

What exactly is a UPS???

Uninterruptible Power Supply, which is just a battery and inverter built into a chassis (often alongside some other circuitry, like surge protection, boost/buck circuits, etc.).

 

[Xen]

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

 

[solderdude]

Transformers hum.
Even common mode chokes can hum.
Sometimes these devices start to audibly hum a little louder over time.

When you put your ear on any mains fed device you are likely to hear a hum.
Some hum louder than others. In some cases it can even be audible up close or even further away.

It has absolutely nothing to do with the mains 'quality' nor will anything you do about mains quality be of any help simply because it is just a mechanical hum from the transformer inside.

An UPS won't help here either. If anything most of them (when actually being regenerative otherwise they don't do anything but charging their batteries) have a sine-wave output that is even worse than the actual mains.

 

[DanielT]

There has been 2xamp, pre and a DAC tested at home all with exactly the same issue. I just received the pre and the DAC from the manufacturers, after stress test and sensitive measurements and no problems, only in the apartment. This are quite new equipments, under five years old. Also mechanical isolation has been ruled out.

It's something in the grid complicated to analyze and to measure, also the neighbors doesn't have any real power hungry appliances, just as usual, nevertheless I am unaware of any electrical installations by themselves. I wanted to practically isolate the apartment but the grid is shared in the building and there haven't been any changes since the issue started.

What exactly is a UPS???

OT:
Ok. I was thinking about electrical safety, in case there was something wrong, incipient fault in the electrical system in your apartment. It is much more important that it is investigated than an amplifier, but you said that has already been done:

I hired an electrician and everything measurable was below the standard regulations,..

Beyond that I don't have much to add. As for the electrical system in a home, it is absolutely not something I would tinker with myself (or give advice on).
I would, and have, hired a professional electrician do that in my home.

 

[DanielT]

It has absolutely nothing to do with the mains 'quality' nor will anything you do about mains quality be of any help simply because it is just a mechanical hum from the transformer inside.

But TS has tested various devices and they only buzz in his apartment, see #13. That's what's strange.

 

[solderdude]

OP stated:
a couple of weeks ago I started hearing a subtle buzz from inside the amplifier-pre-DAC

He tried several 'solutions' (which all don't work of course) and the manufacturer did not find anything wrong (I suspect the hum is normal for the used transformer).

I don't think he took the amplifier-pre-DAC (all-in-on device) ? to some other apartment and did not hear it hum there.
At least that's what I got from the op.

 

[Palmer]

Without make and model it is hard to help, here people open equipment up and analyze, measure things. I have a hard time with this "my car is making a noise" approach, it is 2025 and obviously access to a computer is not a problem - haven't seen even a picture, yet. Not trying to be unfriendly, I have German heritage - being specific goes a long way.

Cheers.