MIKE ROSS wrote in a message to Roy J. Tellason:

 MR> "Roy J. Tellason" wrote to "Jasen Betts" (02
Feb 03  04:06:16)  ---
 MR> on the topic of "Monitors"

 JB> MIDI is also balanced,

 RJT> No it's not.  Typical driver circuit is one resistor to +5 and another
 RJT> tied to the output of an open-collector TTL gate.

 MR> MIDI is 5mA current loop, logic 0 is current ON.

Right.  But it's still not balanced...

 JB> but AFAIK most midi line driver circuits arent up to driving the
 JB> signals long distances.

 RJT> Yeah,  a couple of 220 ohm resistors at the driving end and one more
 RJT> at the receiving end don't give much margin when run off a +5
 RJT> supply...

 MR> MIDI spec is 50 ft max but 100 ft is not unusual.

So they used 74xx in stead of 74LSxx parts on the driving end,  or CMOS
instead of 74LS on the receiving end...

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