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External USB 1 & USB 2 devices Question

  1. Dec 30, 2011 #1
    Will using USB 1 and USB 2 devices in the same desktop PC that has USB 2 ports slow down performance because of the USB 1 device being added to the system? I know that if you use a USB 2 hub and add a USB 1 device to it that the entire hub slows down to USB 1 speed. But Im interested to know if the same thing can happen to a PC if you're not using a hub, just the computers ports.

    Here is my concern...

    I have a USB 1 midi keyboard and a USB 2 audio interface (soundcard)

    Sound quality is obviously very important when it comes to music production.. Im concerned that the USB 1 midi keyboard might slow the USB 2 audio interface down to USB 1 levels which would be a disaster for processing audio signals.

    So does anyone know what will happen?

    Thank you for any help!!!!
  2. jcsd
  3. Dec 30, 2011 #2


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    It should not slow down the 2.0 device as long as they are plugged into separate USB ports. If they are in separate ports they are using separate controllers, if they are plugged into a hub they are sharing the same controller...
  4. Feb 4, 2012 #3
    I have an older Fujitsu Lifebook that has 1.0 USB and no cd/dvd drives. I just added a Syba 2.o Card Bus to give me 2 new USB 2.0 ports and it works great.

    There is one exception though. My Samsung external DVDRW drive (has 2 USB connectors linked together) isn't getting enough power to operate.

    My question...can I plug one of the USB connections into a second computer (to pull power) and the other into my laptop to install software?
  5. Feb 5, 2012 #4


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    Unfortunately, the two USB ports are probably powered off the same USB host IC. Can you reach the second plug around the laptop to the other side (assuming there are USB ports there?) I'd be a little leery of plugging in the second USB plug to another computer or even a USB-output wall wart since the 5V lines from the two are probably tied together. A mismatch in the voltages could lead to some unpleasantness.
  6. Feb 5, 2012 #5
    There are ports on the other side, but they're 1.0 - my next question was going to be using a USB-wall charger - sounds like a bad idea now.
  7. Feb 5, 2012 #6


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    I dont know if youve already tried this, but if the USB 1.0 (12 Mbit/s theoretical maximum - overhead) has enough current sourcing to run your DVD drive, I'd just use that. Wikipedia says that 1x DVD runs at 10 MBit, so as long as its just for data or the occasional use, you'd be okay.

    The other alternative is to use an externally powered USB hub. Or if your external DVD drive has a power adapter available, to use that.
  8. Feb 5, 2012 #7
    Unbelievable! Plugging both leads into the 1.0 ports works - assumed it wouldn;t. Thanks!
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