[sdiy] MIDI phantom power...over 5 pin MIDI connector ?

[rsdio at audiobanshee.com]

Thanks, Neil, for sharing that link. I found it very interesting to read that long (in duration) thread. You certainly know what you're talking about.

In general, I find that the MMA has done a better job than many standards bodies (don't get me started on USB-MIDI, which was designed without the MMA). But I am surprised to see that they seem to be allowing non-engineers to make decisions about interpreting the spec. As you say, it's not hard to understand.

I'm glad we're discussing this, because I never looked closely before to see that there are two distinct ground symbols. I'm certain that was not an accident, especially considering the design goal of avoiding ground loops.


On Sep 10, 2015, at 2:00 AM, Neil Johnson <neil.johnson71 at gmail.com> wrote:
> Found the discussion I had with the MMA on this issue:
> 
> http://www.midi.org/cgi-bin/forum/forum.pl/forum.pl?m-1171180161/s-all/
> 
> Neil
> 
> On 10 September 2015 at 09:58, Neil Johnson <neil.johnson71 at gmail.com> wrote:
>> What I find particularly funny/frustrsating/disappointing is how many
>> people don't understand the MIDI spec.
>> All this talk of "5V" and "220R resistors" completely misses the point.
>> 
>> *sigh*
>> 
>> Here's a clue: the text of the standard makes no mention of voltage.
>> Chapter 2, page 1, "HARDWARE".  The circuit given on page 2 is an
>> illustration of one implementation.  I've also discussed the wording
>> in the standard with the MMA and their response to the vagueness in
>> the standard is "well no-one's pointed this out before, and we don't
>> quite understand why the spec was written in this way, so, umm, la la
>> la la..."
>> 
>> 
>> Neil