USB cable causes digital noise!???..

[Activ-8]

First of all, My new Direct Injection box works perfectly! I bought an Art - DPDB which is a dual DI box and it works so good I have just ordered another one (from Juno records) so I will have all of my synths going into these boxes and then onto my soundcard.

I have just done some extensive testing using balanced & unbalanced cables and comparing going direct into my soundcard and also monitored with sennheiser HD25 headphones and visually with Ozone 5 advanced. With Ozones EQ I can take a snapshot of the noise and compare different cables and synths noise.

My findings are of course only for my system but a lot should be applicable to many other situations.

First of all I had a massive hum & digital noise from my Mg slim phatty, this was the biggest problem and was clearly audible. Running the slim phatty into the DI box and lifting the ground (switch on DI box) completely removed the noise!
I also tested using an unbalanced cable and a balanced cable from the slim phatty to the DI box and although the slim phatty output is unbalanced I got the best result (least noise) from a balanced cable, maybe because it's newer & better quality?

Next my DSI Tetra. This has stereo (2) unbalanced outputs that gave me that nasty digital noise. The Tetra midi is connected via USB and this is where the noise seems to come from. If I unplug USB cable while listening the digital noise disappears. So I added the DI box inline and BINGO! the noise vanishes.   I also tested balanced and unbalanced cables again like with the slim phatty but conversely it is the unbalanced cables (the older and mis-matched cables) that offer less noise than balanced!

So finally I come to the Microbrute. It was the least of my noise problems and still benefitted from the DI box and the little bit of digital noise I could detect was gone with a flick of the ground lift switch! Like the Slim Phatty, the micro brute worked fine with a balanced cable from the unbalanced output to the unbalanced input of the DI box.

I hope this little test will help other people as I had no idea what a DI box was and the nasty digital noise was everywhere.
Good luck!

Antony
www.biomedigital.co.uk  <---- My EDM record label.

Thanks guys!, this is great to know!, i will def look into this all of this and have more of a study but for me though this isn't an audio problem as such, i have perfect sound once usb is unplugged, so for me i may have to get one of those usb isolators?, but i am not sure what to do yet.. 

[Biome Digital]

Don't try to make a simple problem more complicated. 

The problem with my tetra was only with USB plugged in like your microbrute. If I unplugged the USB the audio was fine. Try a half decent DI box and if it doesn't work you can just return it.

Whatever you decide. Good luck with it. 

[Mmarsh]

This ground loop usually happens when your computer is plugged into a different Mains circuit than you synths. One thing to try is to plug all your gear into the same outlet using a quality power strip.  Give that a shot and see if it helps.

[redragebrian]

I have this same problem. Tried 2 different computers, 2 different sound cards, 2 different USB cables, 2 different wall sockets. Problem persists.

Had a Mopho with USB, this never happened.

Set up 1 - iMac. Motu 828 MK2.
Set up 2. Macbook Pro. Motu Ultralite Mk 3.

Is this a known deign flaw? Should I return the synth to the shop and get a new one?

Brian

[mckenic]

Thank you for posting the fix with a DI box - I will try that as my Santa present Micro also has this issue... Im not 100% sure that my bedroom is not wired to 2 different electrical circuits but hoping the 'ground lift' will sort my issue! Thank you.

If that fixes it, my only issue will be my lowest C# key not triggering 8 out of 10 times - no word from Support yet 

[kikendo]

I get this problem too. DI box purchase is totally out of the question. Any other solutions?

Since I sequence the Microbrute from my computer, I must have both plugged in at the same time.
Could it be that both my soundcard and MB connect to the same USB hub, however the MB's power plug is connected to a different outlet than my computer and USB hub?

[robman84]

Sorry to resurrect an old post but I have just managed to fix my problem with UsB causing digital noise. I tried different hubs, plug sockets, ferrite wires etc to no avail. However as a last resort I tried swapping around the inputs to my soundcard (an audigy 4 pro with external box) and the noise went away completely! There must be some internal wiring difference between line 2 and line 3, but for me, problem solved. In the other input I now have the Monotron and Volca and they don't get the digital noise presumably because they are not connected with USB.

So if you have this problem you might want to try swapping inputs on your soundcard.

[kikendo]

I managed to remove this myself.
For SOME reason one of my hard drives was causing the noise. Unplugging it makes the noise disappear.
This drive was connected through an extension cord so perhaps it is the extension cord that is improperly shielded what is to blame.

So my recommendation is to fiddle with any and all cables you can until you find out what the culprit is.The microbrute seems to be fiddly with earthing.

[pinellos]

Hi, just my 2 cents : i've had the same problem with my MB (digital noise when USB cable connected). I've buy a MIDI-USB adapter (m-audio midiport) to connect the brute through the MIDI cable but -!surprise!- the noise was still present, now when the midi cable is plugged in the brute (a little less maybe but still present).
Now, i've simply inverted the MIDI cable from the MIDI adapter to the MB and the noise is gone (!!!!!)...
Maybe is the midi cable that have some sort of ground ??
The problem is solved for me, before i've tried ALL the tips read here and in a lot of other places (ground loops, hub usb, balanced cables) except for the DI BOX, nothing have worked.
Only solution for me: USB/MIDI adapter and the correct way to the cable.
Hi!

[Emperor12]

I have the same problem. It is not the outputs....but as soon as I plug in the usb cable on the MicroB then I get this 3-4 db hum/buzz....so at this point the synth is useless to me and its brand new.

[pinellos]

try a midi cable, and a midi adapter USB/MIDI (about 15/20 euro)....
I've observed that a lot of analogue synthesizers have the same problem: doepfer dark energy II too, and some digital synth like NovationMininova (in this case the issue is similar but not the same: the volume of th synth is always > 0, even then the volume knob is full closed....)....
Solutions:

1 - DI Box
2 - USB/Midi adapter and a midi cable
3 - A simple noise-gate in the effects chain 

any other ideas?

[Tikki]

i have the same problem , tryd different usb cables and settings , even when i turn off the microbrute and keep the usb cable in i ge tthe noice , if i use a usb hub the sound is even much more ...
i tryd to plug laptop and microbrute in different power sockets also in the same , and still get the sound
no way to ignore the background noice it needs to work propperly ...
i also dont want to use a external usb midi and use the device as it is intened , i want to use the usb to midi cable for connecting other synths and keep the usb ports free
hope arturia can post a sollution for this , i tryd different options here from the forum and didnt change
PLEASE some support
thanks