Dual Displays from one thunderbolt port.

Discussion in 'MacBook Air' started by trueredsoxfan58, Mar 29, 2015.

  1. trueredsoxfan58 macrumors member

    Joined:
    Aug 5, 2013
    #1
    I have a 2013 MBA and two DVI displays i would like to use. Is it possible to to use two external DVI displays at the same time (with internal one closed). Is there a dock I can buy with two DVI outputs. I would rather not use a DisplayLink adapter.
     
  2. boast macrumors 65816

    boast

    Joined:
    Nov 12, 2007
    Location:
    Phoenix
    #2
    If OS X supported it, you could do this with an MST DVI hub, but Apple doesn't.

    For the Thunderbolt dock method, you would have to do something like buy two docks and daisy chain them with a monitor connected to each one. I believe some have gotten it to work by using a hard drive with two TB ports daisy chained after the dock.

    Other than that, the USB method might be the least expensive.
     
  3. jdechko macrumors 68040

    Joined:
    Jul 1, 2004
    #3
    Not directly and certainly not cheaply. The display output on the current Air is over thunderbolt, which itself is DisplayPort and Data muxed into one conduit. Your standard Apple, run of the mill DisplayPort to DVI adapter strips the DisplayPort output from thunderbolt and converts the signal to DVI. A simple hub adapter wont work because the DisplayPort signal can only be routed through 1 adapter.

    However, thunderbolt is also designed to allow daisy chaining, so a TB device accepts a thunderbolt signal (DisplayPort + Data) and can strip off either part but can also pass along a fresh, new thunderbolt signal (DisplayPort + Data).

    Working from there, you can daisy chain multiple thunderbolt hubs (like the CalDigit Thunderbolt Dock, each capable of outputting HDMI (which can be converted to DVI). So your setup would look like this

    Code:
    MBA -> TB Cable -> ThunderBolt Dock -> TB Cable -> ThunderBolt Dock
    Some docks may also have DVI out instead of HDMI, but you'll have to make sure you buy at least one dock with dual thunderbolt ports to make the daisy chain. In fact, the second thunderbolt dock doesn't need to be a dock at all. Any thunderbolt device with dual thunderbolt ports would work.

    Now I also said that it's an expensive proposition. The CalDigit dock is $200 without a TB cable. Elgato makes one that is $220, but includes a cable. Belkin also makes one that is $299 with a cable. Those docks have HDMI out, so if your monitor doesn't support HDMI, you need and HDMI to DVI dapter. The second "dock" can either be another dock like I mentioned above, or even an external hard drive Like the Lacie d2 Thunderbolt 2 (3TB drive, $299 with cable) . The only caveat is that the second device needs to have dual thunderbolt ports.

    Finally, the biggest caveat. I haven't personally tested a setup like this, so I can't guarantee that it would work. But from reading about thunderbolt and talking to other people, this should work.
     

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