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USB Ground Loop Isolator - Full speed or High Speed?

Gytaxor

Inspired
what is USB ground noise?

is it this metronome like tone in the back of the really distorted tones? Cause I was wondering what that is ... :)
 

Shenks

Experienced
USB Full speed 12Mbit as quoted on the product description is not anything to write home about. It refers to the very first incarnation of USB.

USB 1.0 - 12Mbit
USB 2.0 - 480Mbit
USB 3.0 - 3.2Gbit

Whether the product will resolve your issue I'm not sure. Noise and general audio interference can be a nightmare to fix as there can be many, many factors involved and a logical, methodical approach is needed. Good luck with this and keep us posted as to how you get on.
 

Kingjimmi

Inspired
The USB standard specifies both sides of the cable to be grounded. The device you linked to looks like it proposes to isolate one side and break the ground loop using an isolator chip and then some additional power filter circuitry. Don't have any experience with the product, but the reviews seem glowing. Sounds sound to me, as in you're not buying complete pseudo-science placebo effect.
 

javajunkie

Moderator
Moderator
you need a high speed, it will not work with the axe-fx if only supports full speed.
I have another brand of something similar. It didn't work with the Axe-fx, it did work with a MIDI interface the has a ground loop issue.
 

ralphonz

Inspired
Thanks JavaJunkie. It is as I feared!

Have you managed to eliminate the ground noise?

It makes no difference for me if I plug the computer into the power conditioner (that the axe is plugged into) or into a different socket. Anyone know of any hi-speed isolators or other solutions? I've managed to get rid of all the other ground loops in my studio but USB is still giving me issues.
 

Boogieman

Inspired
I have not designed equipment to USB specs for several years and I no longer have the detailed interface specs. I don't recall the interface grounds having substantially different grounds than the main devices that use them. If you plug the Axe-Fx and the sending computer into the same grounded outlet and have common-mode ground currents flowing there is a problem with the sending computer USB internal grounding: design or anomaly. I had a Dell that apparently had one of those problems as there was a noisy potential difference between the computer and the Axe-Fx clearly measurable with an oscilloscope. I dumped the computer. I'm skeptical about anything in the interface that filters or breaks the ground as the only good ground is a broadband low impedance ground and both of those approaches violate that concept.

Good luck and keep us informed.
boogie
 

ralphonz

Inspired
Thanks Boogieman.

It's definitely a problem with the computer. Everything inside the computer looks as it should, the power supply is grounded to the case and apparently all it's connections are grounded. The computer does give off a lot of ground noise on the built-in audio connections as well as the USB ports. Seems to be a computer ground problem but I don't know how to fix it, most google searches only return results for laptops! I'm using a desktop computer with an ASUS P8P67-M motherboard. If I disconnect the computer from my set up all hum goes away. Firewire to and from my MIDAS desk is also fine, no hum there once the ferrite block is attached to the firewire cable. Active monitor ground hum was solved by using balanced connections from the desk.

All my equipment is plugged into a furman power conditioner.

Any help would be appreciated as I'm stumped but I'll carry on searching! Thanks again.
 

Zwiebelchen

Fractal Fanatic
Have you btw tried recording with a laptop running on battery?

I'd say this solves 99.9% of noise issues on recordings. DC is an amazing thing.


Nowadays, I just take a cheap laptop to recording sessions, record on battery, then send everything to my PC for DAWing. Dealing with ground issues is a waste of time when the magic happens in the DAW anyway.
 

ralphonz

Inspired
As I said its not a laptop its a desktop. I don't have a laptop at the moment and I want to run the axe as outboard in the studio.
 

Zwiebelchen

Fractal Fanatic
Have you btw checked the mainboard connection of your USB socket?

You can check your mainboard manual for the pin layout - but most mainboards also have it written on the hardware (but your view might be obstructed by other cables).

This is the typical connection layout for the USB pins on your mainboard for USB 2.0 sockets:

Check if the GND pins are properly seated. Maybe it's just a loose connection.
 

ralphonz

Inspired
Thanks for the info Zwiebelchen. I'm not sure I can find the pins you are talking about on my mainboard. The USB pins on the mainboard are not used, I'm using USB sockets that are on the back of the machine, housed in metal casing and soldered to the PCB.

There are 3 groups of USB ports attached to the mainboard (no cables). I've tried plugging into all of them including the USB 3.0 ports and still get ground noise on all of them so I don't think its a connection issue with the sockets.

Just to be clear here is an image of my board with the USB sockets labeled:

BDWMDzYspyDBzsva_500.jpg
 
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ralphonz

Inspired
Wow, that is expensive! I don't think I will be able to spend 209 Euro to fix my ground problem but thanks for the link :)

If you ask me it shouldn't be happening in the first place!
 

Solarfire

Experienced
This method may cure your problem, if not you’re only out of one USB cable.

In the middle of a USB cable, strip away a section of the insulation to expose a 1/2 inch of the braided shielding. Cut the shielding entirely away exposing the 4 wires in the middle. Make sure the shield is completely disconnected by testing for contact (continuity) on the opposite metal ends of the cable.
Test the cable with just this mod.

If noise persist proceeded to cut the “black” wire that supplies a ground source through the USB cable via pin #4.

Time to test the results.
 
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Zwiebelchen

Fractal Fanatic
I've tried plugging into all of them including the USB 3.0 ports and still get ground noise on all of them
In that case, just ignore my comment. It's pretty much impossible that all ports have a faulty ground, especially if they are on-board usb ports.

So the issue must be somewhere else in your machine. Power supply would be the next suspect.

Btw, did you plug your PC and the Axe into the same outlet?
 

ralphonz

Inspired
In that case, just ignore my comment. It's pretty much impossible that all ports have a faulty ground, especially if they are on-board usb ports.

So the issue must be somewhere else in your machine. Power supply would be the next suspect.

Btw, did you plug your PC and the Axe into the same outlet?
Yeah, I've tried plugging both into the power conditioner - no change.

The computer power supply is a brand new fanless PSU: Welcome to Seasonic USA

As far as I can tell it's all wired up according to the instructions, hard to believe its the thing causing the issue. I had the same noise with a previous PSU before I bought the axe. Anyway the PSU is screwed in properly and all connections seem fine.

Starting to think its just a bad design of the motherboard or something...
 

ralphonz

Inspired
The strangest thing just happened...

I was about to try solar fires suggestion and cut up a USB cable, so I grabbed an old-looking one. Before I cut into it I tested it with the axe to make sure it was a working usb cable - when I plugged it in the noise was gone (well it's still there but it's much quieter - I can only hear it when I turn up all the gains past unity on the desk and move the mouse around). Any other USB cable I use brings back the ground noise...

So that will do for now as it's not coming through in any audible way on my recordings and it's not annoying me when I'm using axe-edit...
 
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