[sdiy] Who apart from me things the whole MIDI board needs replacing ?

Gordonjcp gordonjcp at gjcp.net
Wed Jan 26 13:11:49 CET 2022


On Tue, Jan 25, 2022 at 10:41:49PM -0500, Mike Beauchamp wrote:
> On 1/25/22 10:31 PM, Brian Willoughby wrote:
> > I brought this up with designers before, and someone claimed that it's easy to select panel-mount 1/8" jacks that are electrically isolated from the panel. Of course, that works until there are supply issues and someone in your sourcing department decides that another panel-mount 1/8" jack is "equivalent" ... except that it's no longer isolated.
> > 
> > I prefer the DIN where the shield and ground are separate from each other *and* separate from the MIDI signaling. That makes it *much* easier to ensure against ground loops.
> 
> I've never used 3.5mm midi. .but could this problem be "solved" with a
> custom cable where the shield doesn't connect at one of the ends?
> 

I have solved a similar problem in the past with a custom jack cable with the braid connected with a 470 ohm resistor at each end.

Makes bugger all difference to shielding (because 470 ohms or 235 ohms if both ends are grounded is peanuts compared to the infinite impedance of the braid in free space), drastically reduces ground loop currents to the point where they don't have an effect.

-- 
Gordonjcp



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