USB cable causes digital noise!???..

[Activ-8]

Hello everyone!, i have microbrutes audio out cable going to my mixer, then the mixers cables going to my apogee firewire duet and it sounds fantastic!, but as soon as i plug the usb cable from the microbrute into my MacBook Pro i get this horrible annoying constant digital noise!???, its not loud but definitely noticeable, especially when i move my mouse and go between different windows/apps the digital noise makes even more weird digital noises???.. also when i unplug the audio out cable the noise goes away?, so i really don't understand, i hope this can be fixed because i'd like to be able to use both at the same time so i can sync up with my music software.. what do i need to do to fix this??...

[KrisM]

Are you using balanced cables from the mixer to the Duet? I don't think this will be an option for the MicroBrute to mixer, but are you using the shortest cables you can at least?

Also, never let a cable carrying an electrical signal (in this case the USB) run parallel to an audio cable. Try to have them cross perpendicular if they must touch at all.

Sadly, I see things like this a lot with audio devices that have USB on board and my suggestions may not help

[Activ-8]

Thankyou for your reply!, the duet firewire can't have balanced cables so it just has to be unbalanced..?, i have a 1meter long stereo mini jack to rca cable coming out of the headphone output of the microbrute going into a rane ttm56 mixer and it sounds great, the master output of the ttm56 is balanced trs to xlr cables to my monitors, no mater how or where i put the usb cable this digital noise is still there..?, in the instruction manual for the microbrute they recommend ferrite cables.. would finding and using a usb cable with ferrite core filters built into it work?, or would buying ferrite clip on filters work too?.. i am quite annoyed with this problem of digital noise, no matter what i unplug and plug in and move around this digital noise is constantly there... plus i have been waiting 3 days for a reply from arturia tech support and nothing!???.

[Bacon]

If I were you I'd use the Line Out instead of the headphone output. The headphone out is just that – an output for your headphones, not for connecting to a soundcard or any other line level input. The headphone amplifier in the MicroBrute may well be picking up some noise that isn't present on the line out.

[Activ-8]

If I were you I'd use the Line Out instead of the headphone output. The headphone out is just that – an output for your headphones, not for connecting to a soundcard or any other line level input. The headphone amplifier in the MicroBrute may well be picking up some noise that isn't present on the line out.

thank you, yeah i thought that might be the case but i don't have any 1/4" mono jacks to y-cable rcas to check that theory at the moment, the manual of the microbrute says the headphone and line outputs are controlled by the same master volume, so in my mind/logic they would be the same circuit but just different sized monojacks.., maybe the ring of the mini trs is the culprit???, this is why i really need the arturia tech support to get in contact with me!..

[Bruno@arturia]

You should indeed use the Line output instead of the headphone. Line output is unbalanced mono. You can use TS or TRS cable it does not matter. but as it's mono output, you don't need a Y. you will have nothing on the right channel.
I don't think using ferrite will help in your case, it sounds more like a ground loop somewhere.
Do you have this hiss if you plug MicroBrute straight to the duet?
Do you have it if  connected to the mixer without the duet on the mixer?

[Activ-8]

You should indeed use the Line output instead of the headphone. Line output is unbalanced mono. You can use TS or TRS cable it does not matter. but as it's mono output, you don't need a Y. you will have nothing on the right channel.
I don't think using ferrite will help in your case, it sounds more like a ground loop somewhere.
Do you have this hiss if you plug MicroBrute straight to the duet?
Do you have it if  connected to the mixer without the duet on the mixer?

great thanks for this, thing is i only have a rane ttm56 mixer so i need a monojack to dual rca cable going from the micro so it can plug into the ranes left n right female rcas, then i can have the microbrute in both my left n right speakers.., also i thought the headphone output is a mono jack the same as the bigger output jack?, it is a mono synth after all right, why would you have a trs/stereo mini jack output plug for headphones if its not needed?, the headphone jack has to be the same ts/mono as the main output is it not?.

[Activ-8]

Update!.., i still have this digital noise when ever i plug the usb cable into the microbrute, i now use the audio out of the microbrute as i have the proper audio out cables and its plugged straight into the sound card.. even the headphones plugged into the microbrute have this digital noise.. i have tried every which way and only the microbrute is broadcasting this digital noise when the usb cable is plugged into it and the macbook pro, once its unplugged theres no digital noise at all.. apart from the faint oscillator noise in the background.. which i am beginning to wonder about to now!.. so its unusable like this, me not happy at all now.. 

[Biome Digital]

Hi, I just registered to give you some tips. I also have a microbrute. Loving it so far. I also have a dsi tetra and a Mg slim phatty. I have noise/hum problems too. I don't believe for a second its your Microbrute as you say you get the digital noise when the USB is plugged in. This is also the same as my tetra. When no usb plugged in the audio is just fine. As soon as the usb cable is inserted to the tetra the digital noise appears. I am not too bothered about this as its very low level.

My Mg slim phatty however has a MASSIVE digital noise and hum! Conversely my Microbrute is the QUIETEST of all my analog synths and considerably cheaper too! lol

Now, The slim phatty is NOT connected via usb (it's using DIN midi connector) and if I pull the mains plug out of the Mg sp while listening the digital noise disappears! I believe my problem (and probably yours) is a GROUND LOOP. I am just this minute about to go and buy an "ART Z Direct Professional Passive DI Box" which has a "Ground Lift Switch" which should hopefully remove this noise for me. You could wait till next week and I will report back how it went or you could try it yourself.    

I hope this helps you as I know how frustrating this noise is and I have just done every test I can to narrow it down.

Good luck!

[Biome Digital]

I am actually looking to get a Palmer Pan 01 Pro DI box now. Also I would check if your using balanced/unbalanced cables and what you soundcard is (balanced/unbalanced).

[Activ-8]

I am actually looking to get a Palmer Pan 01 Pro DI box now. Also I would check if your using balanced/unbalanced cables and what you soundcard is (balanced/unbalanced).

Awesome thank you for posting and your help!, finally some one else with this issue.., the thing thats got me stumped mainly is that when i pull the power cords out of everything and i only leave my macbook pro plugged into the mains i still get this noise when the usb is connected to microbrute..?, and when i have my MacBook Pro on battery the noise is worse!???, my gut tells me this is not a earth/ground loop, it can't be because it gets worse when using only battery?, its definitely a noise loop of sorts.. but how and why???, the microbrute is acting like an amplifier of my macbookpros inner digital workings...??, i have been looking at buying a usb isolator.., but i'm not sure yet, i will wait until you have reported back with your DI box experiment.. thank you!.

[Biome Digital]

Hi, If its not a groundloop its still interference of some sort and that goes down your audio cables so if your audio cables goes to a DI box and is converted unbalanced to balanced then that will hopefully at least give you a clean signal to record. That should be the main goal I think. 

My DI box is being delivered today. I chose an ATR DPDB (dual DI) so I can DI my slim phatty and microbrute. I will report back as soon as its delivered. It might not even work though so fingers crossed! 

[Bacon]

I get this problem too whenever the USB cable is plugged in. However, I noticed that the level of the noise is independent of the output level on the Microbrute. So my solution is to turn the Level knob fully clockwise, maximizing the signal to noise ratio. This way the unwanted noise disappears into the background noise, at least on my Microbrute.

[Biome Digital]

OK I have FIXED ALL MY NOISE PROBLEMS!


I am writing a detailed post now so please bear with me.

[Biome Digital]

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 benefited 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!