Transformer Hum (again)

I just spoke to an electrical engineer and he basically told me that the amp is probably susceptible to hum with audible harmonics in the incoming power, and that a filter of sorts may fix it. He went into a little more detail but I couldn't keep up, so it appears that the Isotek Syncro was working well, I just need a more powerful power block. I asked if an electrician can do something with the incoming power, however it seems that would require a device which if done right would cost $$$$ I guess that's why Isotek and others specialize in just this field. It's frustrating for sure, being a bit OCD and not having the cash to buy pretty expensive solutions sucks!

Hi have a chat to airlink. ...they seem to do some hefty units...at reasonable prices. As an aside to this I wonder whether the proliferation of smart electric meters will increase mains hash .... to the point we will all require toroidal isolation......

Cheers Richieroo, I actually just e-mailed Airlink 5 minutes ago......That's an interesting point about the new smart meters, I had never considered that. I get a kick out of learning about this stuff, it's very fascinating, albeit a bit voodoo for my noggin".

I think you should replace the Isotek Sirius power board with a non-filtered, non-switched power distribution block.  The Sirius is probably holding back the whole system. Try a standard cheap one to start, plug it inte the Syncro, and your whole system will probably benefit. 

Best regards

Hans

Cheers Hans, I am looking at that idea now. If I had been more experienced with this part of the system I would have taken a different path. Live and Learn

Hi Steve
Sorry to read of your ongoing issues with mains quality.  

Given the number of posts that we have exchanged on this subject, you will recall that I went the route of an Airlink balanced power supply on a humungous, dedicated radial supply.  It continues to work beautifully, cutting out some of the noise and DC offset (i.e. asymmetric waveform) without slowing or otherwise constraining the system.  However, I suspect that the main benefit has been in its role as a DC blocker.

Others (Huge, I think?) have achieved the same result by use of a simple, heavy duty, DC blocker for the NAP250.  If you search through his posts on the "Suffering from those transformer hum blues?" thread, you should find more.  This may well prove to be a more effective and cheaper solution than another Isotek type box.

Best regards, FT

Mike-B and I both have homebrew solutions.  However, it's against forum AUP to discuss them, and for good reason: We both have prior experience of designing and building electrical equipment and are safe using mains voltages - this isn't the case for most people.

If you're not confident building such a unit, then FT's principle of getting a sparky to install a balanced isolation transformer wired Centre Tap to Earth and driving a dedicated spur, is the correct solution to pursue.  If the transformer is big enough (at least 2kW capacity) then there should be no loss of performance.  Don't forget that the isolation transformer will probably hum like a good 'un, so it shouldn't be fitted inside your listening room.

Thanks FT and Huge, you have given me food for thought. The amp isn't screaming, but it's enough to annoy. I have treated the room quite heavily and ambient noise is only 40dB so it stands out. I appreciate your kind advice, it helps a lot. Cheers Steve

an aside to this I wonder whether the proliferation of smart electric meters will increase mains hash .... to the point we will all require toroidal isolation......

Made absolutely no difference to my set up. However the new box on the bloc, the 250.2 hums like a bee in a bag especially late evening when listening levels need to be lower.

Loki posted:

an aside to this I wonder whether the proliferation of smart electric meters will increase mains hash .... to the point we will all require toroidal isolation......

Made absolutely no difference to my set up. However the new box on the bloc, the 250.2 hums like a bee in a bag especially late evening when listening levels need to be lower. 

Same for me,  I had a thread running on it.   https://forums.naimaudio.com/topic/smart-meters-uk.    The way the new gas & 'lecky meters measure amps & gas flow is the same as its always been; they have an addition reader/sender added that sends a ZigBee signal to the inhouse Smart Meter,   & also a separate transmitter that sends the daily/weekly power/gas units used over a secure network (similar to cell phone) to your supplier.  .........    Bottom line is there is no detrimental anything,   & for further reassurance,  Naim's new product line has ZigBee remote controls instead of the traditional/current IR 

Richieroo posted:

Hi have a chat to airlink. ...they seem to do some hefty units...at reasonable prices. As an aside to this I wonder whether the proliferation of smart electric meters will increase mains hash .... to the point we will all require toroidal isolation......

 

This has been covered before in the forum. In the UK at least there will be no more hash or interference on the mains from smart meters. The meters connect back to the billing system by radio (exactly what radio system depends where you live) and the electricity meter/communications hub, gas meter and in home display talk to each other using zigbee at 2.4 GHz. Later there will be 868 MHz zigbee for houses where the components are not sufficiently close together for 2.4 GHz to work reliably. There is no power line signalling involved at all.

best

David

Wil shortly have the necessary test equipment to be able to see exactly why power supplies hum. A UKAS calibrated lab grade mains generator which can generate arbitrary waveforms, including nasty clipped mains, spikes, noise etc. It is going to be fun...

The only way I have solved mine is to turn up the music! .. luckily most of the time it is not loud enough to bother me, but once in a while it will just start humming loud enough to wake me up .... but those only last a few mins usually, then it goes back to humming quietly.  I have tried a DC offset device, with no success. 

Is it a hum or a buzz? Mine's more buzzy than hummy.  HQ toroidal windings are known for it when voltages change. Apparently that indicates different issues. I contacted the gurus at RA and here are some practical solutions to try:

• Earthing: check earth continuity. Is it buried under the house? If it's too dry it can lead to problems.
• Try Reversing the neutral and live wires in the plug to see if it's related to a polarity issue.
• Clean all connections.
• Check the socket: are the wires screwed In tight and clean?
• Try Dampening any resonance of the case: try a heavy book for starters to see if that isolates the issue.
• Ultimate cure : Balanced mains, but transformers in the unit will buzz too, all though changeable trappings an minimise this. Ideally located away from the listening room, preferably at the consumer box.

Thanks All for advice, Before I went to bed last night I checked the amp, it was purring with a very gentle hum barely audible. Today I will try turning on different appliances but since I have a dedicated line I am wondering if it is the mains coming into the house? This issue is not breaking me, it is a just a puzzle I would love to find a cure for.

If anyone is interested, I just plugged the Isotek Syncro directly into the 250DR, and it had zero effect. So, when all the kit is plugged into the Sirius with the Syncro to the wall socket it's near perfect -  if only enough current got to the 250. I have no idea, but I wonder if plugging the 250 into the other spare socket on the wall socket (being a double) whether that creates problems at all, perhaps with grounding? When I had the wiring done I didn't ask about a stronger ground with the sparky as I had no idea at the time. It could be that Huge and FT are right and it may require a transformer from the likes of Airlink. Any ideas anyone feel free to suggest them, every new bit of info gleaned helps me grasp this stuff. I wish Naim had educational advice on this stuff, even without offering electrical fixes (their lawyers would love that!)

In this latest test, was the 250 plugged into a different wall socket (even a different socket on a 'double')?
If so, that's a little concerning, it may be that there's a fault on that socket.

Hi all, I'm reading this tread with great interest as I have an active  set up and you all know how many transformer boxes that involves. (8 big toroids - what a buzz!)

I too was thinking of getting isotek syncro but after heaps of reading decided not to as there may be a drop in sound quality when used with a naim system. Looks like these devices sort of restrict the amps ability to get as much current as it needs. The local Australian distributer was not too keen on letting me borrow one and I wasn't going to fork out that sort of money just to try it out.

My boxes hum and buzz randomly but never through the speakers. It really doesn't bother me when I play music as I play rather loud and it's just not audible at all. I also use the room for TV viewing and it is easily audible during dialog scenes. This sort of annoys me especially when my wife also points it out. 

Looks like the best hope is the Airlnk transformers, and luckily they are available here in Australia. Would love to know what naim think about these or if anyone has tried them over here.

Looked at their web site and there is a 5kW model that gets wired into the house supply. It may hum but who cares as it could be installed outside or under the house, well away from the listening room.

Only thing we really need to know is whether it has zero effect on sound quality and of course if it fully removes the hum. In the scene of things it was priced quite well, about A$850 which is a lot cheaper than a Syncro!

Best

Mario.

John, you seem to be confusing the mains input with the low voltage speaker output - the current capacity doesn't match across these because of the transformer (yes - the one that's humming!); and transient power is delivered from the reservoir capacitors, not directly from the transformer.

Yes Huge thanks you are quite right I have confused things - have deleted my original post so as not to muddy the waters further.

johnG posted:

Yes Huge thanks you are quite right I have confused things - have deleted my original post so as not to muddy the waters further.

OK, I'll follow suit.

Mario posted:

... Looks like the best hope is the Airlnk transformers, and luckily they are available here in Australia. Would love to know what naim think about these or if anyone has tried them over here.

Looked at their web site and there is a 5kW model that gets wired into the house supply. 

Hi Mario,

You may find the answers to your questions in the following thread:  "Suffering from those transformer hum blues?". It is one of mine from 2015.

best regards, FT

The humming is an odd thing which has definitely varied according to which Naim box I've had in my system and is not necessarily proportional to transformer size. The worse culprit I've had was an XPS which you could easily hear from the listening seats. One 'tip' I found on the forums and which worked on the XPS was to slightly loosen (one quarter turn) the bolt restraining the transformer (which is on the bottom of the case). This made the humming much more bearable (I had the XPS on two stools so that I could play with the bolt's tightness and observe the effect on the level of hum). Not sure why this worked, possibly something to do with the vibration level, but it did. I'm not necessarily recommending the approach but I have to observe that, for me, it worked. Fortunately the current Naim boxes I have are essentially silent.

whsturm posted:

The humming is an odd thing which has definitely varied according to which Naim box I've had in my system and is not necessarily proportional to transformer size. The worse culprit I've had was an XPS which you could easily hear from the listening seats. One 'tip' I found on the forums and which worked on the XPS was to slightly loosen (one quarter turn) the bolt restraining the transformer (which is on the bottom of the case). This made the humming much more bearable (I had the XPS on two stools so that I could play with the bolt's tightness and observe the effect on the level of hum). Not sure why this worked, possibly something to do with the vibration level, but it did. I'm not necessarily recommending the approach but I have to observe that, for me, it worked. Fortunately the current Naim boxes I have are essentially silent.

This just goes to show that some isolation between transformer and casing would help to reduce audible buzz. Something so simple, one would wonder why it is not already done. 

I have a Isotek Synchro to my Nap250.2. No humming sound now. I do not think that the synchro change the sound from the 250.2 except eliminate humming sound.

If I understand earthly electrics aright, the buzzing is a result of the voltage being sub-optimum for the finely attuned transformer in the NAP. The wires are effectively clattering together. The tappings in the balanced mains unit allow you to 'tune' the voltage to minimise the humming of that unit. That is obviously not an option with the Naim units (and I wouldn't want to try). Here in Valhalla you can ask the supply board to check your voltage as they are obliged to supply at a set standard +/- a small percentage. There are all sorts of reasons why it might vary, though