Nord Stage 4 - Audible buzz from power supply area

[JMacDotCo]

I thought you might be interested to see the response when I contacted Nord technical support about the issue. I think I was speaking with someone at their UK distributor, Headline Audio. Here's my questions and the responses:

Thanks, is there any way you can inform me what amount of humm is expected from the instrument?

It shouldn't be intrusive, however there may be some hum when very close to the power supply.

I've spoken to other users and it seems a certain amount of power supply humm is normal with all Nord keyboards (link to this thread)

Some comments here are inaccurate, a prime example is the OLED inverter. There is no such thing, inverters were used for older LCD fluorescent flat panels. The NS4 uses a conventional transformer but excessive noise is extremely rare as they are “potted” in a resin that virtually eliminates mechanical noise. It may be that the power board PCB is slightly loose but without checking can’t be certain.

How do I know if my keyboard is experiencing the expected amount of power supply noise, or if it's worse than it should be?

By comparing side by side with another keyboard. Also consider some people may be more sensitive to unexpected noise or the environment is far quieter, their stand/desk they are using is absorbing or amplifying this type of noise.

(I told him in a further response that I had tried comparing with a Novation Summit, and heard no noise whatsoever)

It would be annoying to go through the hassle of a return with the supplier, only to receive another keyboard with the indentical amount of noise.

I understand, but you have to judge if the hum is significant enough to be a problem. The fact we are having the conversation suggests it needs to be checked given the grade of the product.

Based on his responses and the fact that the noise is still annoying me, I've asked Gear4Music for a replacement. If the replacement doesn't have the noise issue, then happy days! If it does, then at least I'll know it's to be expected. I like the NS4 so much that I'm prepared to deal with the annoyance once I've exhausted the possibility that a replacement might be better!

(Since I last posted, I tried picking up/pressing on certain parts of the board. I noticed that the noise is alleviated if I lift the keyboard up off the stand with my arms supporting the board near the center. Hopefully it's a power supply module that's not quite screwed down as suggested by the rep, and by another user in this thread).

[AnTerKo]

Hi OP

Did you get a replacement? If so, how is the new unit? Still buzzing? I just bought a Stage 4 with the same problem, so I too am thinking about asking for a replacement.

[icemonk]

i remedied this in a nord stage 3 88 . theres an RF shield that apparently doesnt really do anything is a certification requirement , place over the power supply . i removed it and my board was silent . i have a nord stage 4 on order and will likely do the same thing

[icemonk]

upon further research it would seem the nord stage 4 does not use this sudo RF shield .

vibrations could be potentially remedied by applying some laquer to the core of the transformer ( this is a common fix for noisy transformers), but i havent personally seen whats inside of the black plastic enclosure around the transformer on the nord power supply board. would love to .

this seems to be a mod that would be a great discovery for nord users , as this issue has plagued the nord community since inception .

of course one user actually removed the entire power supply and put in inside an external box . lol

keep raising a stink about this .... or lets find a solution

-icemonk

[JazzP]

My new Nord Stage 4 88 (bought this month, panel v 2.23) produces an audible buzz/hum as well (it is actually more a tone at ~300 Hz). I can hear it even at 1m distance in my quiet studio, which is really annoying. I already contacted my dealer who offered to swap it for another new unit; weirdly enough, this unit had the same issue, so it might be a series problem. He is going to contact Nord to hear what to do (he promised me that he will find a solution).
My previous NS3 was very quiet, as is my NE5.

Recognizable issue to anyone with a new NS4?

[Eumel]

Hi folks,

I do think the problem is not inside your keyboards, but in the way you do yor cabeling.

Please try the following:

1. Don‘t mount your power cables and your signal cables so that they run parallel.

2. As the nords do not have symmetrical outputs (unfortunately), use very short unsymmetrical cables (maybe 20cm) and go into a DI-Box.

I hope this helps.

Cheers

Eumel

[JazzP]

Hi folks,

I do think the problem is not inside your keyboards, but in the way you do yor cabeling.

Please try the following:

1. Don‘t mount your power cables and your signal cables so that they run parallel.

2. As the nords do not have symmetrical outputs (unfortunately), use very short unsymmetrical cables (maybe 20cm) and go into a DI-Box.

I hope this helps.

Cheers

Eumel

Thanks for your sharing your thoughts; however, in most of these cases (in mine for sure!) we're talking about buzz being acoustically emitted from the hardware unit itself, and not buzz/noise that is in the audio signal from the outputs.
Yes, it is always advisable to keep power cables and audiocables separated and use a DI if possible, but that is in this case not related to this kind of problems.

[cgrafx]

there are two possible sources of noise on Nord keyboards.

1. Transformer on the power supply
2. DC to DC converter used in the OLED display

Transformer noise/buzzing would either be in the 50/60 hz range (or 100/120hz harmonic) coming from the primary transformer connected to the line voltage supply, or it would be in the 10khz or above range if its coming form the flyback transformer in the switching circuit.

The DC converter circuit in the power supply or the DC-to-DC converter for the display could also be the source of the buzzing.

"A DC-to-DC converter humming or buzzing sound, often called "coil whine," is usually caused by the power inductor vibrating due to alternating currents and pulse waves in the audible range."

[JMacDotCo]

Sorry for the old thread resurrection. I never replied after my last message.

I did indeed get a replacement NS4 Compact from Gear4music and unfortunately the replacement had the exact same audible noise from the power supply area of the board. I assumed at this point, along with reports from other users, that it's just an inherent flaw in this particular model. I've never had a chance to check out any other Nord keyboard since discovering this problem in my own so I've no idea if it's a bigger problem with the NS4 compact vs any other models.

On the plus side, the replacement was a later revision with the light grey sliders (vs the original black sliders), which I prefer, so I guess there was a slight silver lining!

Overall I just love the keyboard, but I can't help but feel depressed about the buzzing. At the moment I tend to play most often after my missus has gone to bed, in the corner of a quiet room, using headphones, and the buzz is just ever present.

It just shouldn't be an issue on an instrument of this calibre. I also think I'm getting a slightly creaky keybed but I could be imagining it. Maybe I'm just hyper sensitive to noise!? If anyone else has found a better solution to the noise issue, I'd love to hear it!

[SorenP]

Hi, my old Nord Piano also has a slight 50Hz mechanical hum from the god old mains transformer. As an electronics repair guy, dealing with repairing audio equipment for over 30 years, at any time I prefer a traditional 50/60Hz mains transformer compared to a more modern switch-mode power supply. Its almost indestructible, cheap, reliable, and can be replaced by any local tech. The downside can be mechanical hum, probably dependent on your local mains voltage etc.