On Fri, 25 Dec 2015 13:38:01 +0100, Yves Guillemot wrote: >Le jeudi 24 décembre 2015, 11:48:07 Bob van der Poel a écrit : >> I believe that the MIDI spec >> >> http://www.midi.org/techspecs/electrispec.php >> >> says that you must have a opto-isolator. Devices without one are >> probably not compliment ... don't know about direct usb connections. >> > >MIDI uses an unipolar signaling which is very sensitive to >electromagnetic noises, in particular those ground loop generates. >That's why MIDI standard requires an opto-coupler. > >USB uses a differential signaling and can works without any galvanic >isolation. Signal routes could be very tricky. A keyboard could be directly connected by MIDI to the PC, but audio of the synth might be connected to other gear and this gear is connected by audio to the PC. Galvanic isolation and an open shielding always could make a difference. There's also to keep in mind, that connections could be done by USB to MIDI DIN adapters. In the last 35 years music equipment became much cheaper, electronic components became much better, but design of circuits and/or carefulness of soldering and assembling became very worse. ISO 9000 is just crap to provide good-for-nothing idiots a quality management manager job to reduce quality, before that hype the quality of circuit design and carefulness of soldering and assembling was much better. 2 Cents, Ral -- http://www.grundgesetz-gratis.de/ _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
