From arjan@prognosis.nl Sat Nov 01 02:58:02 2008
Subject:Re: V5 MIDI out power mod?


> > Not really, MIDI power is not part of the official MIDI
> > standard. Even
> > the MIDI solutions website (manual) agrees with me on that:

> You're reading a little extra into the spec., IMHO.

Not quite _who_ you are saying is reading a little extra into the
spec. In my opinion it's those who believe that the ability to draw
power from a MIDI out follows from the specs.

> 1. There is no standard for MIDI power.

Agreed

> 2. There is a standard for having the ground connection on
> a MIDI Out or Thru jack connected to 0V in the product
> (per the diagrams in the original MIDI v1.0 specification). >
Voce products do not follow this convention.

If that's what Voce did then shame on them ;)

There is also however a standard for having an opto coupler on the
MIDI in. The MIDI solutions product doesn't have that, so _it_ does
not follow convention either.

> If a device follows the conventions in 2) and 3) above,
> statement 1) is moot; the MIDI Solutions devices will work.

Not neccessarily. I'm sure it's possible to design a MIDI out port
that follows conventions 2) and 3) but wouldn't allow power to be
drawn from it.

In fact, even the original schematics do not allow for that
assumption, since it says nowhere how much current that 5V source is
required to deliver. It only needs to provide sufficient current to
travel the max 15m of MIDI cable and power the opto coupler on the
receiving end. That will not require very much. Any power requirements
beyond that by the receiving end are not mandated by the MIDI specs,
not even by the suggested circuitry.

Did I mention lately how much I love my brand new Korg CX-3? :)
Wonderful instrument, good looking, extremely good sounding and very
well designed in all departments including menu's and MIDI
implementation. I'm loving it ;)