My MTP-AV ties all the ground pins on both input and output connectors
to the chassis. This violates the MIDI spec, which is specifically
designed to prevent ground loops by having devices ground ONLY the
output connectors.

I sent an e-mail to MOTU, which of course went unanswered. I called
today and (after half an hour of busy signals) spoke to a rather
obnoxious rep named Steven, who assured me that it was probably just my
unit, and if I sent it in they would replace it with another. I asked
him to test a unit there, and he said he didn't even have one to test.

This seems like a design flaw, not a broken unit, so I don't want to
lose the use of my unit for a week while they send me one with the exact
same problem. Could someone check out their unit? Ground is pin 2 of
the MIDI spec; if pin 2 on an input connector is connected to the
chassis, you have the same problem I do. (Tip: It's a lot easier to
check the pin of a cable than to try to get a probe into those DIN
plugs.)

Could someone see if theirs has the same flaw? I'd also be curious to
see if the newer MIDI Express XT has the same problem.

--
Jay Levitt |
Wellesley, MA | Hi!
Faster: jay at jay dot eff-em | Where are we going?
http://www.jay.fm | Why am I in this handbasket?