[LAU] Galvanic isolation (was: Re: pianos with built in recorders?)

Len Ovens len at ovenwerks.net
Thu Dec 24 17:46:40 UTC 2015


On Wed, 23 Dec 2015, Jonathan E. Brickman wrote:

> USB MIDI has got the risk to cause noticeable MIDI jitter.
> 
> Does USB MIDI provide galvanic isolation? Several times I read claims
> that USB MIDI connections aren't galvanically isolated.
> 
> Standard MIDI connectors make usage of opto-couplers and shield of the
> MIDI DIN connectors is open.
> 
> Certainly all of the USB MIDI connections I have ever tested, are not
> galvanically isolated; I always get trouble with USB signals bleeding over where
> they don't belong.  USB-to-DIN adapters I have used have been better, but not
> perfect.  Is there a make/model of USB-to-DIN (or even PCI-to-DIN if it exists
> anymore) which you know for sure has opto-coupling?  That would be a great boon
> to me.  Sooner or later I'm going to do optocoupling for audio too, probably
> using a TOSLink setup.

PCI slots on motherboards are getting hard to find. However, it seems they 
all still have two serial ports as headers if not on the back. Maybe try 
this:

http://www.maxmidi.com/diy/serial/

Note: this is old (I better pdf it) it makes mention of ISA slots :) But 
it would still work fine now. There are serialport midi drivers for Linux.

--
Len Ovens
www.ovenwerks.net


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