Buzz when USB cable is connected

I have a severe issues with buzz noise and hum when the USB cable from Alesis Mixer is connected to the laptop.
Strange is, that when I use a different Drumcomputer (DR660 instead of DR880) the buzz noise is not anymore present. Any Idea where I built here something like a hum loop? I already turned some power plugs. All of them are 2 pol. Only the laptop has a 3pol plug with a following AC/DC adapter, Thanks Carsten

I’m not an electrical engineer, but I think this has more to do with bad shielding than ground loops. Though balanced cables to the speakers helped me with this on my previous UR44.

The fact that a different USB device doesn’t do it might point to the culprit.

Hi Steve, thanks for you message. Maybe its really a shielding issue of the audio wires. Will try out. It is more or less unlikely that the DR880 owns a defect. The device is nearly new even it is old :wink:

Makes sense. It could be a design flaw, or USB cable too. This type of thing is like voodoo to troubleshoot.

1 Like

Here an update to the circuit and the Issue: In case both of the USB cables are connected to the laptop, it hums/buzz very loudly. If only one of them is connected, no buzz noise is present anymore

It is Voodoo and try & error

Are all these devices plugged in to the same receptacle? This is probably not your issue, but I’m mentioning it because it seems to get overlooked a lot. I always start electrical troubleshooting at the receptacle with a Klein (or whatever you choose) receptacle checker for:

  1. Correct wiring (Hot, Neutral, Ground).
  2. Ground. I live in an old place that’s all been converted to 3-prong receptacles, but upon checking, only the bathrooms and kitchen (places where there’s running water!), have active grounds. The bedrooms, living room, etc. have no grounds at all. The 3rd prong in those is just so you can plug stuff in, I guess. I can only speculate that the rewiring job was “grandfathered in” to be in building code compliance.

Never hurts to begin at the receptacles.

This is a must when I go into a live gig venue to check all their receptacles and try to find good grounds before hooking up all the gear!

Does anything change when you unplug the laptop
and run it on battery power (at least while troubleshooting)?

Can you record the hum on your phone and post it? That will help to tell if its a ground loop or something else.

If you haven’t already, I would recommend you try changing out your USB cables for ones with ferrite chokes as in the image below.

Also, try swapping around your USB connections to your computer. I would start by having the two trouble makers on different root hubs (if you’re unsure, check the Device Manager in Windows).

1 Like

Hi…yes, all devices are pluged into same receptacle. I am living in a rather new building and everything is up to date regarding house-wiring, I use this USB Adapter

Hi…this USB cable is similar to mine. But only with one ferrite on the Device-Side (Square one on your picture left connector)

Nothing changes by operating the Laptop with battery power only! Buzz is still there

Thats the buzz noise. can not make it louder…

There seems to be no audio

I hear it.

Is it better to have on both sides a ferrite choke ? Or is one enough?

I can’t say. My guess, based on some experience, is that one more ferrite choke will not eliminate this issue or even make a difference. I have had issues with USB cables that had poor shielding where replacing the cable with one with chokes did make it better.
Did you try moving the USB connections around?

Update: Even when the USB cables are not connected to the Laptop but connected to each other via the USB-Hub the noise is present.

Additional I disconnected the loudspeakers from the Alesis mixer and tried out with headphone only: Buzz still present!
Headphone connected direct to Drumcomputer: No buzz!!!
But I still can not believe that the Alesis Mixer is defective.
Update: I changed the mixer: Buzz still present!

So it’s either your alesis or dr880. Can you lift the ground connection for each one and try?
Could also be the hub. What if you connect both to laptop without the hub?
Or try another hub?