From Brian Willoughby Sent Thu, Dec 27th 2018, 02:08
From Brian Willoughby Sent Thu, Dec 27th 2018, 02:08
Wow! I=E2=80=99m very disappointed that the MMA approved 1/8=E2=80=9D TRS = jacks for MIDI on small devices, for the very reason that it=E2=80=99s = common to connect the Sleeve of a jack to the metal of an enclosure or = modular face plate. Granted, some people have pointed out that it=E2=80=99= s possible to carefully select 1/8=E2=80=9D TRS jacks where this = grounding is prevented and/or to manually install insulating grommets = and nuts, but that sounds like a headache waiting to happen. For my MIDI builds, I use jacks that are plastic, and which screw to the = enclosure or face plate without any possibility for ground connections. = What manufacturer and part number have you been using for MIDI jacks? = I=E2=80=99d always assumed that it=E2=80=99s easier to find non-grounded = DIN-3 jacks. Brian Willoughby On Dec 26, 2018, at 6:04 PM, Michael E Caloroso = <xxx.xxxxxxxxxxx@xxxxx.xxx> wrote: > While we're discussing studio MIDI wiring... >=20 > ...I build my own I/O panels for my racks, and my own MIDI cables. I > recently uncovered a nasty bug that has perplexed me for years: >=20 > If you use metal shell MIDI plugs on your DIY MIDI cables, DO NOT > ALLOW MIDI GROUND TO COME IN CONTACT WITH THE SHELL. >=20 > I was gigging my road system and was experiencing intermittent MIDI > errors. After finally being able to reproduce it at home, I figured > out that the metal shell of the MIDI plug shorted to earth ground via > the metal DIN jacks I was using on my DIY I/O panels. Stray shield > wires from the cable had contacted the cable clamp of the plug > (despite my best attempts at trimming the stray wires), completing the > short circuit of MIDI ground to earth ground. MIDI gets very upset > under this condition. >=20 > I use an EBTech cable tested after I build all my DIY cables, and it > does not have the capacity to detect a short from the shell to any of > the pins - it's not supposed to. Even with my diligent testing after > completing a cable, this bug had eluded me for YEARS in my studio > system. Yes I was well aware that the MIDI specification grounding > system is designed that way FOR A REASON. >=20 > The only way to guarantee complete isolation of MIDI ground from earth > on the metal shell of the plug was to disassemble the plug and add > shrink tubing over the trimmed end of the cable. This separates any > stray shield wires from the metal clamp of the plug. Once I fixed my > cabling for the stage rig, it behaved MUCH better. >=20 > Nasty bug, this. >=20 > For years I had wondered why my SYSEX dumps were never 100% reliable, > now I know why. >=20 > That's just the STAGE rig. Now I have to make the cable corrections > to my STUDIO system, which has easily over 30 DIY cables that I built. > Guess how I am spending my holiday break... >=20 > Sent from my iGroundingCanBiteYou, > MC >=20