[sdiy] Who apart from me things the whole MIDI board needs replacing ?
cheater00social at gmail.com
Wed Jan 26 17:38:50 CET 2022
I'm not fully sure, but I believe this was said to be a bad idea in
the relevant Rane app note.
On Wed, Jan 26, 2022 at 4:35 PM <rburnett at richieburnett.co.uk> wrote:
> > 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.
> That's a good point.
> Often you can solve problems like this by connecting the shield to
> ground via a 100nF capacitor and 1Meg resistor in parallel (at one or
> both ends.) The impedance of the parallel combination is low for
> high-frequency signals (and most noise that has come through the air
> before coupling onto your cable is high-frequency in nature,) and
> conversely the impedance is nice and high for low-frequency signals
> (like 50Hz "hum" currents due to earth loops,) so not much current flows
> at these low frequencies. The 1Meg resistor prevents static build up
> across the 100nF capacitor, so it at least tries to keep them with the
> same DC potential if one of the bits of kit is "floating" relative to
> the other.
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