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USB Line Extenders

zekezebra

zekezebra

pfm Member
Hi - has anyone here got any experience of extending a USB connection over the 5 meter limit using something like this: USB Line Extender

I'm trying to connect my laptop, using jRiver, to my DAC but it's just that bit too far away. Alternatively there is this but a bit pricey: Icron USB Ranger

Thanks
 
Would if I could :( Problem is that I work in one half of the room, on the computer, and the DAC is on the other with a gap across a doorway.
 
zekezebra said:
Hi - has anyone here got any experience of extending a USB connection over the 5 meter limit using something like this: USB Line Extender

I'm trying to connect my laptop, using jRiver, to my DAC but it's just that bit too far away. Alternatively there is this but a bit pricey: Icron USB Ranger

Thanks
Click to expand...
In general, they work - I have not met a single case where they wouldn't (when using a single "self-powered" 10m cable, without connecting it to another cable, just straight host<->device). However they are not guaranteed to work, as explained by the usb-if FAQ:

1. Why are there cable length limits, and what are they?
A: The cable length was limited by a cable delay spec of 26ns to allow for reflections to settle at the transmitter before the next bit was sent. Since USB uses source termination and voltage-mode drivers, this has to be the case, otherwise reflections can pile up and blow the driver. This does not mean the line voltage has fully settled by the end of the bit; with worst-case undertermination. However, there's been enough damping by the end of the bit that the reflection amplitude has been reduced to manageable levels. The low speed cable length was limited to 18ns to keep transmission line effects from impacting low speed signals.


2. I want to build a cable longer than 5 meters, why won't this work?
A: Even if you violated the spec, it literally wouldn't get you very far. Assuming worst-case delay times, a full speed device at the bottom of 5 hubs and cables has a timeout margin of 280ps. Reducing this margin to 0ps would only give you an extra 5cm, which is hardly worth the trouble.


3. What about using USB signal repeaters to make a cable longer than 5 meters?
A: Don't bother. The best solution is self-powered hub with a fixed 10m cable that had a one-port bus powered hub in the middle. The maximum range will still have to deal with the timeout, so any out of spec tweaking of the terminations between the two hubs and the timing budget still won't yield more than 5cm of extra distance. A better solution is described in the following question.


4. I really need to put a USB device more than 30 meters away from my PC. What should I do?
A: Build a USB bridge that acts as a USB device on one side and has a USB host controller at the other end. Use a long-haul signaling protocol like Ethernet or RS-485 in the middle. Using cables or short-haul fiber, you can get ranges upwards of a kilometer, though there's no reason why the long-haul link in the middle of the bridge couldn't be a pair of radio transceivers or satellite modems.
Embedded host solutions capable of doing this already exist. Also, two PCs connected via USB Ethernet adapters are essentially a slave/slave version of this master/slave bridge.
Click to expand...

Note that the 5m limit is for USB2.0 (high speed), not for USB1.1 (or 2.0 in a lower speed compatibility mode), where it is 3m.

The last paragraph mentions something like this, which was also featured in a blog post by Archimago, where it apparently resolved some HF isolation (or ground loop?) issues, when used with a shielded cable, as a bonus to extending the range.

edit: Ah, I haven't checked the links you provided - I assumed you mean the cable-like extenders with an integrated hub in the middle of the cable, since these are generally called "extenders". The ones you linked should work fine without violating the spec.
 
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Don't spend £300 on a solution (Icron). Rather, simply buy a second cheap (s/h?) PC to use for media duties?
 
Whaleblue said:
Don't spend £300 on a solution (Icron). Rather, simply buy a second cheap (s/h?) PC to use for media duties?
Click to expand...

Indeed. You can a G4 Mac Mini that will run JRiver (well it runs Pure Music OK) for around £80 and can control it either with your computer using VNC or with the remote app.

Just checked JR requires Snow Leopard and above but the G4 ends at Leopard. Still leaves iTunes and Pure Music that can be tried.

Laptops come out a bit more expensive due to the screen and keyboard.

Cheers,

DV
 
jirij said:
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Click to expand...
To be more specific; for a simple extender, I use http://krup.cz/default.asp?cls=stoitem&stiid=3700 , similar things can be found on ebay, look for ie. "usb active extender 10m", usually around 7-8 EUR.

Alternatively, http://rover.ebay.com/rover/1/711-5...0001&campid=5338728743&icep_item=390678027847 supports USB2.0 high speed and costs way less than £300.

The solution by Corning also works well for extension, but not isolation as it contains 2 tiny metal wires (not mentioned by marketing materials or relayed by most "audiophiles").
 
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Using a second laptop might not be as stupid as it sounds. You could buy the cheapest, fanless, small SSD machine you could find, put JRiver on it, and it will appear as a zone to your other JRiver machine, so you can play to it. Something like this Asus Transformer Book for example would do you fine, though I am sure there are other options.
 
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Curious, I run a 10 metre USB cable from a Gigabyte mobo to a Musical Fidelity V-DAC2 with no problems at all.
 
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