so I'm creating my own USB-A to USB-B cable using Canare mic cable, what do I do with the braided shielding?

[mrjayviper]

Do I:

1. connect it to ground but only on 1 side? (which side?)
2. connect it to ground both sides?
3. leave it unconnected?

Thanks for the help.

 

[restorer-john]

4 wires and a shield- connected at both ends.

 

[wwenze]

I love that we skipped the part saying why this project would be a horrible idea performance-wise and just went straight to answering the topic question.

 

[mrjayviper]

I love that we skipped the part saying why this project would be a horrible idea performance-wise and just went straight to answering the topic question.

is it because of the cable impedance?

if DIYing USB cables, what would be the ideal cable type? (perhaps a link?)

 

[solderdude]

USB data spec is 90ohm (+/- 15%)
Screened twisted data lines, preferably separate +5V line outside the screen of the datalines, ground thus should be connected at both sides.
When you don't some DACs may not work (that well) any more.
Use the screen of both data lines as the ground connection.

Do you need a certain length that you are making such a cable yourself or plan to make a cable without +5V or ground ?

 

[restorer-john]

I love that we skipped the part saying why this project would be a horrible idea performance-wise and just went straight to answering the topic question.

Maybe he's got several metres of Canare star quad pulled through conduit from one room to another and just wants to use it. It'll work over a short distance, no matter what he uses, but termination to the plugs will not be a fun job.

Or 2 core shielded mic cable is all he has access to right now and he'll run two cables to make a short USB link.

I just answered the question.

 

[mrjayviper]

in saying that, how do I know if the USB cable I bought from a store (online or brick/mortar) is compliant?

 

[solderdude]

Is a specific cable not performing correctly at the highest bitrates ?
It is a digital connection so has quite some tolerance for 'signal integrity' (depends mostly on the USB receiver)

When it works fine (no drop-outs or other weird connection problems) it is at least good enough for that connection.
The connection can take a bit of a beating, certainly at lengths up to 6ft/2m it is not that critical for most DAC/source combinations.

 

[MCH]

At least in USB-c the shield does not go directly to ground but there is a capacitor and a resistor in parallel in between (at the receiving circuit, of course, not in the cable). The ground lines do go to ground, of course.
Not sure if this is what you are asking but just to suggest you to do a bit of research. I hope it helps.
Example:

 

[Roland68]

is it because of the cable impedance?

if DIYing USB cables, what would be the ideal cable type? (perhaps a link?)

Audiophonics has a very good USB cable available by the meter.
https://www.audiophonics.fr/en/digi...pper-ptfe-double-shielding-o78mm-p-11077.html
Data conductors and 5V supply are separated and shielded from each other. Each conductor has high-quality PTFE insulation. In addition, double and tight external shielding and instead of a cheap PVC jacket one made of PE.
The air for improvements is already getting thin...

Supplement:
Only the outer shielding of the cable is always placed on the connector housing to enable potential equalization of the devices.
Never data or USB ground.

 

[somebodyelse]

Just so we have the original reference material, https://www.usb.org/document-library/usb-20-specification - see usb_20.pdf inside the zip file. Sections 6.4.1 (Standard Detachable Cable Assemblies), 6.5.1 (USB Connector Termination Data) and 7.1.1 for the impedance to cover the main points.

 

[wwenze]

is it because of the cable impedance?

if DIYing USB cables, what would be the ideal cable type? (perhaps a link?)

Yea it is because of the cable impedance. And also insertion loss. USB2.0 high speed needs a few hundred MHz so we're missing by 3 zeroes.

If you are having the MacGyver spirit, use LAN cables. They come in long lengths and are designed for such, have close-enough impedance, and work at a frequency close to USB2.0
But of course the ideal cable type would be a USB cable.

 

[mrjayviper]

Do you need a certain length that you are making such a cable yourself or plan to make a cable without +5V or ground ?

I had some spare mic cable and need some short runs (1M and below)

 

[wwenze]

I'd just go to Daiso and buy a USB cable for 100yen. Or even 200yen for the fancy stuff below. Gotta love consumerism society where our time in day jobs cost so much that we spend money to save time. Man, I tossed out a lot of cables and connectors recently, used to keep them for potential parts but all they did was take up space for 10 years in a $1000psf society.

The context changes everything. If you're doing it because you need to, there is no need to. But if you're doing because you want to, then just go for it. Heck, I once made interconnects out of brass wires because ooo they look good.

 

[solderdude]

I had some spare mic cable and need some short runs (1M and below)

That'l probably work if your mic cable has 2 signal wires.
You might need a separate +5V wire (some USB devices need them, others may not).
For this you could use a second cable and parallel the 2 mic wires.
At these lengths mic cable will work just fine.

 

[mrjayviper]

That'l probably work if your mic cable has 2 signal wires.
You might need a separate +5V wire (some USB devices need them, others may not).
For this you could use a second cable and parallel the 2 mic wires.
At these lengths mic cable will work just fine.

the canare cable has 4 conductors + braided shield.

 

[solderdude]

Connect all 4 wires (see post #2) and connect the screen to the the metal parts of the connector.
When it has 2 twisted pairs of wires inside use 1 twisted pair for data and the other one for ground and +V bus. The shields only connected to both metal parts of the connector.

Not an ideal cable but will probably work fine for this distance (1m).

Personally I would just use a generic cable.

 

[radix]

You could look at the USB 2 standard: https://www.usb.org/document-library/usb-20-specification.

Any cable that says something like "USB 2.0" and uses the USB logo has to pass the compliance tests. That said, there are low-speed cables and high-speed cables. There are a variety of electrical (resistance, capacitance) and shielding requirements. Could something else work? Sure. Will it be reliable? unlikely.

 

[Roland68]

the canare cable has 4 conductors + braided shield.

Making a USB cable yourself is actually only worthwhile if you want it to be of high quality, such as the cable mentioned above, or for special configurations/laying. For the latter, for example at Conrad, you can purchase goods by the meter for €1-2 per meter.

Otherwise, the ready-made, inexpensive USB cables from Audiophonics with gold-plated plugs (from €2.90) are more than sufficient and proven.
If you want something to be pleasing to the eye, then take the USB cable from LINDY from the CROMO LINE. In the past, resourceful people have provided these cables with a visually high-quality mesh tube and sold them in the bay for 20-30 times the price. Of course as a sonically superior USB cable that outshines everything else...

 

[nutzandvoltz]

Do I:

1. connect it to ground but only on 1 side? (which side?)
2. connect it to ground both sides?
3. leave it unconnected?

Thanks for the help.

Depends on what you doing.
But if you are making a cable to get rid of computer noise,you don't use the computer side of the grounds, and run the gnd and +5V wire to a separate power supply. Of course, modifying a powered hub is easier to do this.

but if you just building a standard cable, then just connect the shield to gnd.