AW: [sdiy] MIDI over Ethernet (was Microchip DSP kit $60 > AVR32)
Peter.Ullrich at kapsch.net
Tue Mar 25 16:45:49 CET 2008
>> One other aspect that I haven't yet seen mentioned is that Ethernet,
>> like MIDI, has electrical isolation on inputs - opto- isolator for
>> MIDI, transformer for Ethernet. Even with Power-over- Ethernet you
>> still maintain the isolation between input and device via the switcher
>> magnetics. Ethernet also adds isolation on the output as well just
>> for completeness.
>> Unless you spend $$$ on special boxes you don't get isolation on USB,
>> so ground loops and noise-sharing via common grounds start to be a
>> problem again.
>Thanks Neil. If you combine the lack of isolation with the fact that
>you're probably connecting your USB MIDI to a computer with the usual
>atrocious switched-mode power supply, it seems like noise might be
>quite a problem.
Adding iCouplers from Analog Devices could help here.
Galvanic isolation up to 100Mbit/s - they work really fine!
But OK, they are not really cheap...
Peter Ullrich I Hardware Engineer, Research & Development
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