QUESTION: How Many Metre Is The Longest Length of a USB-A to USB-C Cable to Get Maximum Performance?

• 

  Orico on 21/07/2020 - 20:47

  +3

  I'm noob in this of area.

  Forget about everything you just asked and buy a good quality cable. Apple, Blitzwolf, Belkin, OEM stuff from Microsoft, Googlee etc.
  Spend more than $20.

  • 

    CyberMurning on 22/07/2020 - 00:10

    My question is about the length….

    • 

      iforgotmysocks on 22/07/2020 - 08:24

      +1

      Length is not always important, it's how you use it.

• 

  pegaxs on 21/07/2020 - 20:56

  +1

  USB 2.0 is about 5m
  USB 3.0 is about 3m

  It comes down to the quality of the cable used and what you are piping over it. Just data or just power or both, and how much of either/both. You can go beyond these limits, but again, cable quality, design and what you're moving over that cable makes a difference and past these limits, there would be no guarantee that your data would be intact or that you are getting your full charging current.

  Wires all have a resistance that affects current draw over their length. Also the thinner the wire, the less amperage you can draw/push through it, limiting it's ability to charge/run devices over a long distance. Same for length. The longer the wire is, the more resistance, the less it can push through. USB cables are notorious for have very thin wires, so, to pass enough current at the highest rating, they would have to limit the length. You can have one or the other. A nice, thin cable, but it's short, or a big, long cable, but it's thick. (giggity)

  Data is basically just an electrical impulse sent down a line. If that line is too thin or too long, the data may not have enough push to get to the other end and just get eaten up by line resistance before it reaches the other end. So, some data may get there if the line is too long, but some of it wont, so you will get data loss. Data loss = corruption/drop outs/no data.

  There is too much to explain about how electricity and cabling work, but there are lots of good YouTube videos and Google searches that can help you understand if you want to know the engineering of why cables do and don't work.

  • 

    CyberMurning on 22/07/2020 - 00:11

    Ah thanks.. at least now I know 2m is kind of safe.. I won't go extreme 8 metres for example….

  • 

    afoveht on 22/07/2020 - 11:47

    If that line is too thin or too long, the data may not have enough push to get to the other end and just get eaten up by line resistance before it reaches the other end.

    That's not really true. (And words like "push" and "eaten" don't mean much in this context.) USB signalling will likely be more affected by transmission line effects than resistive losses.

    • 

      pegaxs on 22/07/2020 - 13:26

      Yeah, I was just trying to be general. Of course there is a lot more to it, but I didn’t think that OP wanted that much information…

      And the link you pasted, isn’t that for analogue signals and not digital? Digital signals are usually just a + or - voltage square wave. Anyway, I’m no engineer, just going off what I have been taught. I’ve not had much to do with analogue lines and most of my experience with digital data transmission is either through CAN bus or cat5/6 type cabling.

      Anyway, I do like learning things, so I will read that page when I get more time.

      • 

        afoveht on 22/07/2020 - 13:58

        All real-world signals are essentially analog, just that many effects are not clearly manifest or of consequence at low speeds. At high speeds (not necessarily overall clock / data rates but specifically fast rise and fall times) digital signals must be treated as analog signals.

• 

  stirlo on 21/07/2020 - 22:19

  connect my laptop USB-A to a docking station USB-C (and then dock will output display to 2 external monitors).

  This is NOT possible!!! No cable will help with this. Only a laptop USB-C port carries the video signal which the dock uses. A laptop USB-A port does not and will not work for video output with a USB-C dock.

  • 

    D C on 21/07/2020 - 23:58

    Bollocks, USB 2 docking stations have been around for yonks: https://www.mwave.com.au/product/asus-usb20_hz1-docking-stat…, dual monitor even.

    At my last job we had some sort of Targus dock with USB-C input, worked fine with USB 2/3.

    • 

      stirlo on 22/07/2020 - 11:49

      Bollocks, USB 2 docking stations have been around for yonks

      Yes, but thats not OPs idea + shit performance

      Targus dock with USB-C input, worked fine with USB 2/3.

      Link to this mythical product? There's no reason to put a display adapter in a usb-c dock as display port is already in the spec.

      • 

        D C on 23/07/2020 - 02:31

        There's no reason

        Backwards compatibility.

        not OPs idea + shit performance

        Yes so? Fine for work, not gaming @ 4K.

        mythical product?

        As other have said, DisplayLink.

  • 

    CyberMurning on 22/07/2020 - 00:14

    Yes it is possible.
    https://www.amazon.com.au/dp/B07DXHTRCL/ref=cm_sw_r_cp_apa_i…

    But yes, outputting from USB A is not as good as from USB C Thunderbolt…. Too bad my work laptop doesn't even have USB C port….

  • 

    Tigerhacker on 22/07/2020 - 01:55

    They defintiely exist and generally do 1x 4K or 2x 1440p. They send a compressed video signal down the usb 3.0 link (or 1080p over usb 2.0) so there will be minor image degrdation and possibly a cpu penalty but fine for office work and is pretty common.

    If you want to dig into it, the key work is 'DisplayLink' the company that manufactures these chips that dock makers use.

    For optimal image quality you would definitely want a native display connection to the monitor via Thunderbolt/DisplayPort/HDMI though

    • 

      CyberMurning on 22/07/2020 - 08:51

      spot on i should mentioned displaylink, i just recently found out there are different type of manufacturer for dock! previously i thought dock is just simple dumb hardware like an adapters

      • 

        stirlo on 22/07/2020 - 11:42

        previously i thought dock is just simple dumb hardware like an adapters.

        So my advice was correct and saved you from wasting time buying a $30 dual screen usb-c hub and and naively thinking it would work if you converted the USBs

        You're trying to tell me you linked to a $5 aliexpress cable when you planned to buy a $200+ displaylink dock which includes cables anyway? Sure mate…

        • 

          CyberMurning on 23/07/2020 - 08:45

          @stirlo: i was thinking to get longer cable than the included one hence the question about length.
          yeah i learnt my lesson of not getting a laptop with thunderbolt (with DP capability).