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USB Ground Loop Noise filters?


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Hi there!

 

I've been expanding my studio on the recent years and know I have much more hardware analog,digitalsynths/fx/inst than ever before, so I'm not really doing stuff "in the box" so much like back in my student days, and quite frankly I'm loving more and more doing stuff outside the box. Of course I'm still using lots of plugins and software instruments.

One of the things that has started to become a problem is the USB Noise from one of my submixes. Here's a quick explanation of my setup where the problem lies:

 

 

 

Mackie Onyx 1620i Firewire - Thunderbolt adapter - Macbook pro. (both In and out are coming through this one)

 

 

all my synth modules including a couple of send fx units are plugged into an SM10 Line mixer and then sent to a stereo channel input of my Onyx1620i.

 

Now, My onyx 1620i is a very silent, noise free machine, have other stuff connected to it like compressors, mics, other line instruments, etc etc. however it is the submix of the SM10 the one carries sh*t loads of USB digital noise and it is particularly evident when compressing or using saturation/distortion units. In the past it wasn't so much of an issue, as most of my modern digital synths have audio interfaces built in, so I could just record the sound digitally straight into my DAW, but as now its not so much the case.

 

Would using balanced cables help? the SM10 has balanced input outputs but not all my lines connected are balanced.

The problem seems to lie on a couple of usb devices: My keyboard+mouse (they're not cheap quality) and a usb-vgA interface. That seems to be the main problem but theres still some digital noise coming down even when those two have been switched off.

 

Any advise?

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1) Wondering what you mean by "USB noise". For example, when you move your mouse do you hear a brief burst of small pops, like static? Or is it a constant "hash"?

 

2) You mentioned a USB-VGA interface. What exactly does that do, and what brand/model is it?

 

3) Balanced cables are designed to reject electrical interference in your general environment. This can be RFI (radio frequency interference) or even USB "radiation", though the latter is only a problem if you're using USB extender cables. But based on my initial impression, I'm not sure that the problem has to do with unbalanced vs. balanced cables.

 

4) Grounding is almost always an issue when connecting multiple OTB devices, and improper grounding can lead to noise problems. So the first thing to make sure of is that you're feeding your gear AC power (wall power) from a single grounded outlet such as a power strip or UPS that all of your gear is plugged into. That outlet needs to have a proper polarity and ground, something you should test with a cheap AC tester (see image below).

 

Assuming you have proper ground, the power strip should be connected to AC power without a ground lift, and all devices should be plugged into the strip without lifts either. If you then find you have constant noise or hum in your system, you can try to alleviate the problem by selectively lifting the ground on one or more devices. This takes trial and error.

tester.jpg.3aeddffd28ae019a8dc562cf3613becc.jpg

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Ski has it right.. the poor mans version, is buy a cheap three prong adaptor, and clip the sound plug off.. A UPS helps, and is very important for brown outs, Ac fluctuations, If your studio is a house or apartment, (or not properly and contemporary wired, use only one AC jack in wall..   Years ago, I had computer mother boards that would fry after a few months, but none of my home hardy kids..  Took two tech visits.. to discover I had 5 volts floating on ground.. That was enough to fry computer circuits but not affect other devices.. 
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Thanks very much for your reply guys, To ilustrate the point Ive recorded a sample of the noise I'm talking about you can find it here:    - bear in mind it's been gained up, compressed and eq'd to exagerate a little bit the frequencies also tried to get some of the Hiss off so it doesn't distract you from my actual point) https://www.dropbox.com/s/pf2xqk59zlqc3hm/USB%20Noise.aif?dl=0

 

as You can hear there's 3 "constant" tones, high pitched ones (around 1k) seem to be fixed when my keyboard+mouse are off. then there are two mid low hums. One of them comes and goes, that one is coming from my optic mouse, when the hum goes is because I moved it when it comes back my mouse is on standbay. and the thoroughly constant mid low hum is coming from y USB-VGA interface.

 

 

Another thing, at around 10 secs you can hear a couple of crackles, thoseones  happened when I was recorded and created a couple of new trakcs in logic.

 

 

As I said, If I unplugged these Usb devices everything seems to be working ok. The noises are only coming from the Sub mix I explained above. Any thoughts?

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Hey there again, Ski!

 

The VGA-USB adapter is for my second external monitor. I have a 32" HDMI screen hooked to the thunderbolt port and an old VGA Samsung SyncMaster 710n into that vga-usb port.

 

this is the one http://www.ugreen.com.cn/product-756-en.html

 

I haven't had the chance to look at my earth situation because I'm yet to buy that device you kindly recommended.

 

Haven't lifted anything as far as I'm concerned and all my gear is plugged into a voltage regulator does that help with anything?

 

One of the things I just found out it helps a lot if I use the "fancier" USB hub for the problematic USB devices (VGA and Keyboard+Mouse) They're plugged in at the moment to a generic non powered usb hub, whereas my "important" gear is plugged in into a TP-Link 7 port powered 3.0usb hub. When those devices are plugged in that hub it helps a lot.

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Here's an update, so I bought another TP link 7 ports usb 3.0 hub and that has taken care of most of the issue!! All those Mouse hums and VGA hums are now gone the only thing I'm dealing with is the "crackles" just found out those crackles are coming from an external mechanical drive, it seems that when activity is going on and the HD is been read i get bursts of digital noise and crackles.  
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