Ground problems can happen to anyone (no matter how many years you’ve been doing this) and is never usually caused by a single piece of gear - only when you connect multiple pieces of gear in a system... the problem is in the interconnection of all the gear.

You seem adamant (for no real reason) that it is not the cables — when in fact, the right cable with ground isolating capabilities could likely solve the issue, immediately. You should only conclude - the situation was not resolved by any of cable changes that you have made, thus far. It is wrong to conclude that it’s not the cables. The cables are probably not causing the problem either... you can only conclude that changing them did not solve the issue.

These same cables can be used in other setups and not cause a problem — it will depend, again, on all the gear that is interconnected... the cable is just passing along the signal (it makes no judgements about that signal).

The only thing you can/should conclude is the cables you have used do nothing to help remove the ground noise you are getting. Are these all standard USB cables or do they have any ground isolating function? Probably not. It is one thing you may want to look into.

The noise comes from the MODX.

No, actually the noise is coming from your speakers. Right? If you turn you speakers off the noise stops! It is probably not even effecting your recordings (but you won’t be able to tell in your studio because all audio is coming through your system).

You are looking to blame a single item when in reality a ground issue is caused by the interconnection of multiple pieces of gear.
Anywhere you can monitor the sound you will hear the noise due to the connections between devices.

Each system is different. It can have to do with where your items plugged in... Try to get your studio on one electrical (house) line. If half your studio is plugged into one wall socket and the other half is on a different electrical line - this can be the cause. Some times it’s simple, some times, it’s not.

Yes, your house is a part of your system. Ask any recording studio owner about grounding ... I’m not going to recommend you do what recording studios do... but we have a studio in NYC where they raised the floor, lowered the ceiling - built the studio encased in chicken wire (it’s in the walls, floor, ceiling), then they grounded the studio to the cold water pipes of the building, then they grounded the building’s pipes to the Railroad tracks in Grand Central Station. (Thousands of miles of ground) lol

You can’t do that, but offered just so you know: when you connect multiple electrical devices you are going to be susceptible to ground noise... the more gear you get the more likely you are to run into issues.

The noise can be removed through diligence. First, you must properly identify the noise, (is it high pitches or a low buzz? - this will indicate the nature of the ground issue). USB ground noise is high pitched zinging noise, electrical ground hum is low buzzing noise 50 or 60 cycles depending on where you live.

If you are at a loss, get help. Ground hum in the USA (I have tons of experience) but I do not give out grounding advice for folks dealing with 220-240v systems because I have no experience... and folks who think the cause is one thing will do stuff that is shocking (literally and figuratively) and I will not contribute to this...

Here is recent post from some one in your position and their solution. See entire thread - as it is on point for your issue
Link — https://yamahasynth.com/ask-a-question/output-noise#reply-107227

Extra Credit:
The MODX is a 10-in/4-out Audio Interface for your computer via USB (Yamaha Steinberg USB Driver) — just FYI.

I will offer some general insight into Ground Loops (aka Earth Loops). This does not profess to solve your problem.

Imagine a simple interconnect between 2 separate pieces of Audio Equipment, each with its own power supply.

Audio Equipment A is plugged into Wall Socket A (240v AC)

Audio Equipment B is plugged into Wall Socket B (15m away on the other side of the room).

Earth or Ground, in an ideal world is at 0v (Zero Volts).

Therefore, ideally, the earth at Socket A is exactly Zero Volts, and the earth at Socket B is at exactly Zero volts.

Both Equipment A and B use their respective socket's earth as their own Zero Volt reference.

But what if socket A earth is at 0.05v and socket B earth is at -0.03V?

If Equipment A and B are not connected, both eqipment A and Equipment B will work fine.

But as soon as you connect them together with a signal path, whichever end is putting out audio will sound noisy.

This is because the signal connection (digital or audio) is composed of 2 physical paths (copper wire)... A signal path and an earth (0v) path.

If socket A earth is at 0.05v and socket B earth is at -0.03V, there is a difference in voltage of 0.08v. This means current will flow across the earth path in the signal connection (instrument cable, usb etc). This leads to noise and is an earth loop (at least this is one cause of an earth loop).

Imagine another scenario where the earth voltage (remember it should be zero) is actually fluctuating over time. This is known as a dirty earth and can lead to extra Radio Interference (derived from 60Hz AC usually).

There can be many sources of earth loops, inluding faults within a single piece of audio equipment itself. Faulty Jack plugs or their soldering are a common cause I have found.

Getting rid of earth loops and/or radio interference is a true nightmare.

As BM points out, the source could actually be the building you are in. Also, BM advises diagnosing the source is largely a process of elimination.

If I were you, I would start by investing in a special 240v power outlet board, with power "scrubbing" / "cleaning" / "filtering" functionality. Plug this into a single AC outlet, and then ALL your audio equipment into the power board. This will at least eliminate Building earth loops, and is generally a good investment in any complex audio environment. These are generally easy to find on Google. People often buy them for Home AV/Home Theatre systems.

Going beyond this, you may also want to invest in DC Isolated Power Supplies, to get rid of noisy "wall warts"... but that can get pricey pretty quick. You also need know the exact DC requirements for each piece of kit you want to run off the isolator (DC Voltage, Current Draw).

Regards AC/DC transformers... wall warts, power bricks (PC) etc... Very often cheaply made, very often very noisy (RFI), sometimes the cause of earth loops.

Thank you very much for you long explanation Bad Mister.

I just checked one more thing.

- All usb things unplugged. Included mouse and keyboard

- MODX as only audio interface. Analog outputs MODX to monitors.

- USB cable plugged in to my PC; NOISE
- USB cable unplugged NO MORE NOISE through my HS7 monitors. Perfect clean piano sound.
- Tested with 7 USB cables from different manufacturers (some of them high end quality ones)

Clarify this for me please.

Greetings

Just another thought...

Define your noise...

Noise induced on a pure audio path is usually a buzzing or humming sound.

Noise induced (introduced) on a digital path (USB for example) is usually a high pitched whining sound that can vary in pitch, or can appear only on certain sounds that sound as "glitchy" or "fizzy distorted".

Clarify this for me please.

see this post: https://yamahasynth.com/ask-a-question/my-new-modx8-usb-noise-issue#reply-107357

Do any of your USB cables include a ground isolation circuit?
No one cares if their printer has USB hum... high quality in your case could means a special USB cable.

Consult your local music store... they will know how to help you.

Antonio, very sorry you're having noise issues with USB. I use Mac, so despite your using a PC, I have great sympathy with regards odd noises and USB.

Apple has kindly plagued anyone working with audio with their wondrous T2 chips... but I digress...

I can record audio from the MODX (noisy audio) in to the DAW...

Can you upload a little sample of this?

Also, the sound changes you're hearing when you're interacting with the screen on the MODX -- perhaps via iPhone held up close to the speakers.

The noise is the grounding noise that we all musicians know.

I just spent 1,495 euros on this device. If I also have to buy special usb cables separately to test if it does not make noise, badly. I also have the usb cable from my Novation SL MKIII which is a high grade cable. I know perfectly what a good usb, audio or midi cable is, I have been in this bussines for many years.

If the noise that the MODX makes when connecting it to a PC is not a known issue that can be fixed, I return it to Thomman and buy another 88 keys from another brand.

For me this is unacceptable.

Please talk with someone knowledgeable about audio and electrical functions at your local dealer. It’s obvious to me you are not understanding the issue. Please call your retailer, they will be happy to help you resolve the issue.

I've just connected the P-125 of my son to the pc, and no noise. Perfect clean in reaper with VST too.

I think I understand the issue perfectly.

Take a look at your power connections - which outlet each of these devices is connected to. The W10 computer, the Scarlett audio interface, your monitors, and the MODX. Often reconfiguring these connections can make an impact. Some may be plugged into the same power strip (maybe all) - some may be plugged into a 2nd outlet. There may be an extension to another set of outlets. Some power strips even have different circuits on them where one set of plugs is isolated differently than another.

If you have tried different USB cables - and they are indeed different (some with ferrite isolation, some without, some with shielding connected to one side, the other side, or both sides) then you've probably done enough of that. Although I'm not sure you have a more active isolation cable in the mix as these tend to be costly as there is circuitry to isolate even data (not only power/gnd).

Before having to spend those bucks - I would first look at the power connection topology and try different configurations there. If not done already - plugging everything into a common "dumb" power strip with no frills (no protection circuitry, etc) would be one end of that spectrum.

I wouldn't advocate employing ground lift since this defeats protection - but you can experiment with that as well. Your computer and monitors probably are grounded connections.

MODX doesn't have a ground reference. It's a 2-pin power supply. Your Scarlett is probably similarly floating. I'm not really sure what it uses but just going by what I see as the common standard for interfaces and making an inference.

If your W10 PC is a laptop and not plugged into the wall then it's floating too. My assumption is now that your W10 PC means it's a desktop and plugged into a grounded outlet with a grounded cable (3 pins).

I have the same problem with my new MODX6 and my Scarlet 18i20 gen3. The noise is high pitch and not the 60Hz power frequency you would expect, and although MODX is not grounded to the power source as some experts noted here, the Scarlet, my desktop, and the JBL sound monitors are, therefore the MODX is grounded through USB and in/out analog cables.

I am an electric engineer expert in grounding, and I also have a Roland FA08 connected in the same circumstances, with the same high quality expensive cables. The Roland is not making absolutely any noise on the stereo analog outputs. I blame the MODX as I've tried to fix the problem in any way you can imagine. I consider strongly to return it and buy something else that performs and filters the noise more adequately and in a professional manner.

Yamaha, can you offer a solution? Do you stand behind your product? If no I know what to do.

Thanks,

Alex

MODX is flapping in the wind at the outlet with no earth ground connection. This is not necessarily a problem unto itself. However, MODX can receive a ground from related components once plugging in say an audio cable to monitor speakers that are grounded if one of the circuits is grounded at the monitor side or by the USB connection's ground (a longer cable introducing LCR components). So the MODX is not grounded by the outlet but "potentially" through other connections.

This doesn't mean I have any difference with the thought that there may be a design issue causing noise. I'm not really sure - it's something to be explored (not by me, though). Devices such as this including laptops running on batteries complicate issues. The return paths become more difficult to get at the same potential.

And of course - ground loops is but one of many things to tackle. My comments on this front were just due to the relative ease of (re)configuring this due to all parts of this being user serviceable (cables, connections - not only power).

I bought this and it solved my noise problem.
GeeekPi USB Isolator Module ADUM3160 USB Digital Isolation USB to USB Voltage Isolator Board Protection (5KV ESD MAX) with OC Protection