USB 2.0 data rate for HX stomp

[Mcdos22]

Hello,

I'm looking at sorting a ground loop on my USB input to the Stomp box with a USB isolator which has a data rate of 12Mb/sec. This is typical for USB 1.0 at  full speed and  USB 2.0 full-speed also operates at this rate. I note the hi speed data rate specification for USB2.0 is  480Mbit/sec which is obviously significantly higher, but may well not be used in the Stomp.  I can't see any details in the Line 6 manuals for the data rate required to make things work properly and wonder if someone could clarify if 12Mbit/sec is enough please? 

regards

Edited April 21, 2021 by Mcdos22
image nothing to do with post

[rd2rk]

Can't help you on the specs, but can tell you that I tried an iDefender USB 2.0 isolator alternately on every device, and it didn't solve the problem, actually increased the noise.

 

My solution came about through randomly trying every USB connection in every port of my laptop, USB Powered hub and USB-C hub (except the Helix itself, that stayed direct to the laptop).

I wound up with the Helix, Scarlett AI and mouse connected to the laptop's USB ports, my printer, PC212 and assorted MIDI controllers connected to the powered hub, and the powered hub and external HD connected to the USB-C hub on the laptop's USB-C port.

 

With a total of 10 USB devices in the system, it was a nightmare figuring it out. Good Luck!

[CraigGT]

Get a cheap usb lead, nibble at it with cutters until you can see the wires and cut the black one.

Save yourself the expense of an isolator and if it doesn't work you've only wasted a dollar!

[HonestOpinion]

20 minutes ago, CraigGT said:

Get a cheap usb lead, nibble at it with cutters until you can see the wires and cut the black one.

Save yourself the expense of an isolator and if it doesn't work you've only wasted a dollar!

 

Do NOT cut the red wire, 60, 59, 58, ...  :-)

[CraigGT]

Just incase your thinking that you might blow something up,

here's the USB cables for my Helix and Scarlett interface.

 

[codamedia]

On 4/21/2021 at 5:31 AM, Mcdos22 said:

I can't see any details in the Line 6 manuals for the data rate required to make things work properly and wonder if someone could clarify if 12Mbit/sec is enough please? 

 

To answer this question.... no, this would not be enough, especially if you were trying to use the stomp as an interface. The stomp would certainly require the high speed USB 2 rate. USB 1 spec is primarily used by keyboards, mouse, etc...  FWIW, I run all of my low speed USB devices from a USB hub.... saving all the direct USB connections open for the more important things. I have never encountered a group loop issue, but certainly understand they can exist. 

[Mcdos22]

On 4/24/2021 at 8:33 AM, CraigGT said:

Just incase your thinking that you might blow something up,

here's the USB cables for my Helix and Scarlett interface.

 

Hi Craig, that's an interesting suggestion. I can see why it should work as long as there is some other way for the USB ground reference to exist in the Stomp and the host PC. I assume this must be existing via the audio interfaces and whatever the alternative ground connections are that are causing the loop in the first place. I guess my only concern would be if a large differential voltage could build up between the computer and the stomp and maybe damage the USB interface should this alternative grounding be removed, perhaps by accident if the setup is changed.  However, it obviously works for you, so thanks for the idea. FWIW, I did a bit of fiddling about at the weekend and identified the issue with my set up as being due to my external monitor (it has an HDMI and USB interface). Just touching the tip of either plug to the metal of the connector housing on the laptop triggered the ground loop noise.  i.e. connecting either of those to the laptop when the stomp is also connected caused the ground loop, without both all is good. When I first tried it I removed one plug and then the other so missed the fact that the monitor with its built in usb hub is a common source.

 

I think monitors being the cause has been reported by others. The issue for me is use this monitor for everything, but at least I know i can get a fully functional rig until I maybe try your trick or whatever to isolate the stomp. 

 

Once again, thanks for your help.

regards

S

[Mcdos22]

On 4/24/2021 at 12:35 PM, codamedia said:

 

To answer this question.... no, this would not be enough, especially if you were trying to use the stomp as an interface. The stomp would certainly require the high speed USB 2 rate. USB 1 spec is primarily used by keyboards, mouse, etc...  FWIW, I run all of my low speed USB devices from a USB hub.... saving all the direct USB connections open for the more important things. I have never encountered a group loop issue, but certainly understand they can exist. 

Thanks Codamedia,

I suspected this would be the case, however, for most of what I want to do at this point, just using the HX Edit software will suffice and thought it might cope with the lower data rate. My issue has been traced to my monitor, which has an onboard USB hub too so has a USB and HDMI connection. Utilising either of these monitor connections when the stomp is connected triggers the ground loop issue.  Thanks for your feedback :-)

[CraigGT]

I wouldn't worry about  losing the ground reference, it sounds like you already have two :-)

 

I think my PC psu is a bit noisy so I've previously had to disconnect the ground to the Scarlett but I also have a large fan in my room and everytime I turned it on or changed the speed my Scarlett would go silent and I'd have to reset it. 

 

It took ages to find a solution to that but I had to disconnect the ground to get the Scarlett quiet so It ended up with a disconnected ground but with a capacitor to couple the spikes across to ground. Hence all the heatshrink!