Akai MPC ONE CV voltage humming noise when connected

Hello everyone, I have this strangest problem. When I connect my MPC ONE to my eurorack with the CV Voltage and Gate patch cables I start hear a humming noise in the background. It disappears when I press the Midi section in the menu, but when I am back in the Audio section to record the sequence the noise comes back. It`s quite annoying because it will ruin the quality of my recordings.
Now I don`t know if it`s something that happends only to me or are there others that have experienced the same problem?
I will apprecciate your opinion in what can be wrong?
Maybe ground looping problems (like the Arturia BeatStep Pro?)

Hi, did you get rid of the humming noise?
I have the same problem, so I would be greatful for any help.

Hey everyone, I have the same problem
It sounds like a "synth harmonic" in around 150hz.
I noticed that it appears when cv cables stuck from mpc to Eurorack.

well, eurorack systems are known to have ground issues.
i have a 12u system with two different psu's (i had 2 uZeus now i have 1 uZeus and 1 Silta).
if i plug an audio signal from one half of the system to the other, i have hum.
if i plug something like a clock from one system to the other, then the audio signal turns ok again.
i think it's a matter of establishing a common ground.
i think the problem here might be similar. i'm almost sure that if you lift the ground from the PSU of the mpc one the hum dissappears...but it's not safe to do so.
if you also have some midi-cv module, you might want to connect with it the mpc to the eurorack system and see if that establish a common ground and gets rid of the hum.

try this also: using a patch cable, establish a contact between a metal part of the mpc to a metal part of the eurorack system (a metal panel is enough) and see if and how it interferes with the hum.

I've experienced this with the USB B cable going out to computer. The hum shows up only on certain menu screens.

man USB grounding issues make me mad. Eurorack is wacky town shuffling voltage around... but with USB you’d think they would have fixed it... nope...

For either issue you can put a ground loop isolator in line to your audio, but you end up loosing 3-6db of volume... which has the effect of raising your noise floor

/shrug

NearTao wrote:man USB grounding issues make me mad. Eurorack is wacky town shuffling voltage around... but with USB you’d think they would have fixed it... nope...

For either issue you can put a ground loop isolator in line to your audio, but you end up loosing 3-6db of volume... which has the effect of raising your noise floor

/shrug

What would be needed in order to remove USB issue without buying an inline isolator? The strange thing is that it only happens on certain screen. But it looks like I'm going to need to get a Radial Twin-Iso Line Level Isolator or Radial SB-6 Isolator 2-channel Line Isolator.

You could also put some tape over the ground pin on the USB cable and see if it clears it up first... but depends how you feel about running equipment without a ground. Personally I've done it just to isolate where the issue may be... but dang is it annoying.

Sometimes you can fix it by making sure everything is on a common ground... but this depends on how you've got everything plugged in, in the first place. Personally I haven't had much luck with power conditioners... I mean they'll frequently lower the noise if it is there, but it is still there.

NearTao wrote:You could also put some tape over the ground pin on the USB cable and see if it clears it up first... but depends how you feel about running equipment without a ground. Personally I've done it just to isolate where the issue may be... but dang is it annoying.

Sometimes you can fix it by making sure everything is on a common ground... but this depends on how you've got everything plugged in, in the first place. Personally I haven't had much luck with power conditioners... I mean they'll frequently lower the noise if it is there, but it is still there.

The MPC ONE is fully isolated, besides the usb flash drive it's all by itself. It's the only USB device that I have that does this.

Well that's annoying as all get out.

Have you tried putting quarters under the rubber feet or replacing the knobs with wood?

Maybe something like this:


Overview
Leading innovation: Intona has invented USB 2.0 Hi-Speed galvanic isolation.

Previous isolators were limited to Full Speed (12 MBit/s) and Low Speed (1.5 MBit/s) transmission. This product is capable of transmitting USB Hi-Speed (480 MBit/s) while providing full galvanic isolation of both the data and the power lines.
USB 2.0 Hi-Speed Isolator withstands up to 2.5kVRMS

This product is an ideal solution to break ground loops, avoid noise coupling and protect ports from power surges and voltage spikes in applications which require high speed USB transfers. The galvanic isolation barrier withstands potential difference up to 2,500VRMS. There is no capacitive coupling.


https://intona.eu/en/products/

Maybe? It sounds like something that might be worth a try... though the marketing certainly makes it seem $$$$

You could try having all units connected to the same power outlet. Careful not to overload though!

Generally speaking , if the device has it's own power you can safely cut the black wire from the usb cable .

Here's the thing.
There is a hum around 150hz (150 to 164hz) which appears whenever the pads leds are lit and the unit connected to a USB device. The only way to avoid it is to connect a MIDI keyboard without a power outlet (like the MPK Mini), and your external synths via MIDI and NOT USB, i.e: The devices must NOT be connected to AC, otherwise the hum appears.
It seems that the hum is only generated in the main outputs only, the headphones output seems to be ok.
I tried to isolate the power outlets, put a filter before the surge bar, even tried to connect the MPC and External synths somewhere else in the house, same issue. I contacted AKAI, they never replied.
Unfortunately to me it is absolutely a factory defect. Anyways, in the first place the usb connectivity was intended to connect a Flash Drive and a computer (Controller mode) until the 2.8 firmware update
I love this machine, but knowing that, I'd rather spend that extra money to purchase a Live.