1 Nov
2009
1 Nov
'09
1:55 p.m.
On Sun, 2009-11-01 at 12:56 -0400, Raymond Martin wrote:
15 meters is a recommendation based on typical cables used in a simple system.
Data corruption ensues somewhere after 15m, depending on cable quality, EMI,
and so forth. I would imagine a CAT5 as having better shielding and IIRC runs
for that are advised to somewhere up to 50m. Different frequency ranges though,
so signal loss/degradation per meter may vary.
My recollection is that when MIDI was originally standardised, they
needed to specify a maximum length, and that 15M was chosen somewhat
arbitrarily (No tests were done, no eye patterns examined).
Now midi is actually at heart a 5mA current loop interface running at a
fairly low baud rate (31.25 Kbaud IIRC), so should be good for far more
then 15m without any problem, however nobody really knows and it will
depend a bit on the environment and the receiver.
Interference is unlikely to be an issue assuming good quality twisted
pair cable (Cat 5 counts), but bulk capacitance just might ultimately
limit the length.
Regards, Dan.