I'm developing a project where it's preferable to use 3.3V. And there has to be just one MIDI out. I tried connecting ground, vcc and data pins to a midi jack and it works fine with Kemper profiling amp. I tried it without any resistors as well as 220 ohm and 100 ohm on the 3.3V power pin (vcc) and there was no difference.
Is it better to use 5V than 3.3V?
What resistors are needed for each case and why?
(I know that on 5V 220 ohm resistors are used on tx and power pin but I don't really understand why they are used and what to do in 3.3V case)
Thank you!