[sdiy] USB/MIDI ground isolation?

[Manuel Odendahl]

Hi,

On Sep 17, 2009, at 7:54 PM, Neil Johnson wrote:
>>   It seems to me that USB/MIDI has dropped the best feature of old  
>> fashioned MIDI.
>
> Yes, because its cheaper. MIDI over USB is a cheap hack designed for  
> low-cost consumer devices, where cost is more important than audio  
> integrity.  If you want to break the ground loops there are several  
> ways, from USB opto-isolators (very expensive), audio transformers  
> (mildy expensive) to cheap tricks such as ground-lift with a lowish- 
> value resistor.

Am I missing something here? On input, inside the USB/MIDI adapter,  
there is an optocoupler like you would expect. On output, the wires go  
straight through into the optocoupler at the receiving end. Thus,  
every connection is isolated. I don't really understand what this  
thread is about?

Regards, Manuel