Hi there all,

Long time lurker here who thought I would post my findings regarding a noise issue I've had with my new DSI Mopho X4, my Laptop and Motu Ultralite mk3. While I feel like I've arrived at a workaround I'm still interested in what you guys think and any suggestions you may make.

The Ultralite has been nothing but aggro since I got it. The Windows USB driver is pretty bad, constantly refusing to work with other USB devices, NI's Maschine in particular. After OS re installs, BIOS, driver and firmware updates I've got it working to a tolerable standard.

See here for more info:
MOTUNATION • View topic - Ultralite mk3 issues, once last try before clean OS install.

Long story short, I have to follow a strict, monk-like start up regime, that includes plugging in USB peripherals in the correct order at the correct time as well as making sure all programs sample rates and buffers are set the same. etc etc etc ad. nausium

Of course, as all these things seem to go nowadays no one company seems to take responsibility, Motu say it's NI, NI say it's Clevo, Clevo blame Rasputin.

Back to the point of the thread:

I've noticed in the past that when I'm set up at my friends studio, once volumes get quite high, a high pitched machine noise is present above the sound card's noise floor. This, I guess is the laptop's processor/gubbins being picked up through the USB drive and into the MOTU. It never seemed too high, and a quick jig about with gain stages has pushed it far enough back to continue working.

I recently recieved a new DSI Mopho X4 and took the chance to have a sort out in my home mixing/writing room. Plugged it in and had a play, very nice. I then decided to get up to speed with it's MIDI over USB, plugged in the cable and was greeted by those familiar high pitched cycle sounds. I finally decided to get to the bottom of it.

Firstly I tried out moving plugs about, taking various other bits of gear out of the equation until I just had the laptop, soundcard, DSI and monitors plugged in and connected. The squeel remained. I then unplugged the laptop's power cable, no joy. I then unplugged the Mopho's power adaptor, no joy. I then moved onto trying different USB cables in different sockets, no joy.

So with the only the soundcard plugged in to 240v (it's not bus powered) and the unpowered Mopho connected via USB the sounds remains.

The Motu's Cuemix FFT analysis has been very useful in showing me this sound is on the input, not between soundcard and speakers, this is proven by it showing up on recordings. Further more FFT shows the tones starting at 2kHz and then duplicating every 2000Hz, their volume steps up then down by a few db every second or so. Speaking of volume, they are some 20dB above the noise floor.

After spending all last night reading up about ground loops, ferrite beads, power conditioning, ground lifting DI boxes et al. I was just about to get slutty and buy some Radial DIs when I stumbled upon a guy suggesting that instead of taking the dangerous step of removing power cable's grounding you can remove the ground wire in a USB. Seeing that I have a few laying about I thought I would give it a try.

I simply opened up the cable and snipped the black wire that links to pin 4, I left the +5v pin 1 intact as I'm aware sometimes it is used to establish a plug and play connection.

Lo and behold, although the tones haven't gone completely they have dropped a good 15dB and are swallowed up by the noise floor.

Without the USB connected



With a standard USB


and without the USB ground


I am aware of the 50hz, that's next on the list. If anyone wants audio of these I can get some recorded. These were taken with the output of the DSI boosted by my mixer, it's noise floor is lower than these plots.

A few final points.

This doesn't happen with all USB gear, my MIDI controller for instance brings no spikes with it. Although I have heard it at the studio before I purchased the DSI. (my friend has a MIDI controller that has a wall wart, could be the culprit)

I feel that the real culprit is the USB hub on my laptop. While it is an absolute monster it is still a Chinese whitebox, they most probably make their profits on things like USB hubs and defiantly the on-board speakers. And no one suggest Firewire, I don't have it.

It seems strange that it occurs while the DSI is powered off and disconnected from its power adapter, could there be some funky wiring going on inside it?

Sorry about the wall of text, but this has been a complex one, and I want to make sure my first post was a biggie before I descend into monosyllabic grunts about sexy outboard.

Cheers for now.

Can I just say THANK YOU?!!!!

I will get $50 back when I return this Furman power conditioner to GC tomorrow. I carefully sliced open a usb cable with a razor blade, snipped the black wire, and it worked! I a/b'd with my snipped cable and a non-snipped one, and there is a definite whine with the uncut cable.

You are the man.

Of course, cutting the ground wire may reduce or eliminate a ground loop, but it also cuts off the power to the device, so the trick won't work with USB-powered gadgets.
If one is cutting the ground (black) wire, might as well cut the power (red) wire also. As bartak101 says, there are protocols that USB uses to detect the presence of devices which depend on sensing the current being drawn by the device. However, the return path for that power is the black ground wire you just cut. So that means either...
1) There is still a ground somewhere else that is providing the return path for the power sense current, or
2) The device doesn't need the current sense protocol.
One could further modify the cable to cut the red wire to confirm either (1) or (2) above. If it still works, it might further reduce the noise problem. If it doesn't work, it means that the power connection is still required either for power supply, or at least for power sensing. And further, it means that the power supply is returning through some other ground loop path.

Note that there are USB isolation devices which break ALL the paths, including the data wires (using an isolation transformer for the data).

bartak101's account rather confirms the general belief that MOTU gear is pretty much made for Mac users. The fact that it works at all with Windows is rather surprising, IMHO.

Laptops (and tablets and other portable computers) have some pretty complex arrangements to squeeze the most out of the internal batteries, including switch-mode power supplies. This adds to the digital hash from the logic circuits and makes computers rather hostile to really clean audio recording.

Hi,

Im also going crazy with this whine... I went from FW beringer to Avid USB Mini to FocusWrite Firewire - the whine remains...

Lowering the gain or the volume seems the only way to remove this whine.

The whine is definitely from the PC. Time to take it apart...

Took it apart and the whine is still there. I have an external FW card. No usb devices (just a mouse and a kbd)...

Here's the funny part though... When i launch the DAW, there's a moment of silence in the speaker!!! So i think the issue might be the drivers but all 3 audio cards i have do this noise...

The power plugs all have a ground but i live in an appartment and the current is 3-phase, moreover my studio is in a corner of the appartment so i can't plug the speaker elsewhere than the same power line...

Im going to try a different PC to see if the problem is the PC itself...

@bartak101
Man you are a legend!In my case I had more complex setup were 2 samplers where working fine alone ,till I both connect them to my laptop and the noise came.Had to cut the usb black wire on the 1st and cut both the ground and the black on the 2nd.Then I eliminated completely the noise by connecting the ground of my mixer to the ground of the second sampler(not the usb).
It was too complicated to think it by my self , so again THANK YOU!

PS.My first post after 7 years...I forgot I was ever registered to gearslutz!

WOW!! thanks for this, I was getting nuts with this noise and this simple trick worked. My interface is working well too...I guess this just means that I need to keep my interface plugged to my speakers at all time and this connection is now the interface's ground.

But to everyone having these issues this worked great - also, i only cut the black wire and left some of the cable shield intact.

Agree ,but necessary only if the above tricks don't work.

Thank you! Works great on a DSI Tetr4 too.