30' midi cables

[BigKahuna]

I'm in the process of redesigning my control room and where I would really like to place my synths would require me to use some pretty long midi cables (I'd have to run them around the room perimeter). I'm using Sonar as my sequencer, but triggering the sounds in the synths.
Do you think that 30' midi cables would introduce noticable lag in the signal? Has anyone ever had problems with that due to cable length?
I suppose I could move the PC closer to the synths ... but I also use MMC to slave Sonar to my multitrack and I would probably have the same trouble with that connection if I moved the PC to the other side. That is ... if it's a problem at all.
Thanks for your help.

[knightfly]

Normally, MIDI cables are kept to 20 feet maximum. The problem isn't so much lag as it is corruption of the MIDI signal, causing spurious commands, wrong notes, etc -

What happens is this: The MIDI signal is a series of square pulses, the important part of which are rise and fall times, or leading and trailing edge of digital pulses. The longer you make the MIDI cable, the more cable capacitance causes high frequency loss until you reach a point where the cable cannot transmit a square enough pulse to retain timing information. I'm not talking about timing as in "gee, I played that sooner that I'm hearing it", I'm talking timing as in your sequencer sending a module instructions to play a G4 at a velocity of 119, and the module hearing "Play an A5 at a velocity of 55 (119 - 64, for example) -

There are two ways to get around this - the cheapest, if it works, is to buy the absolute best quality (specifically lowest capacitance cable) MIDI cable you can find (just one, for starters, it may not work) and try it. Work really hard at trying to make it NOT work on your most finicky piece of MIDI gear, and if you can't, then get more of them and hook everything up. You may still have problems with some gear and not others, depending on their pulse shaping abilities. Normally what you would experience as a failure would be dropped notes, stuck notes, and anything else not attributable to ham-handed playing technique :=)

The next way would be to get some (relatively) inexpensive MIDI thru boxes (one in, two out, for example) and use two shorter cables with the thru box halfway. MIDI gear almost always re-shapes pulses on its inputs, so the thru box would clean up the edges of the pulse train and give it another 20 feet to get "dirty" again.

I've successfully used 20 foot MIDI cables (store bought), so trying the 30 footers would probably be worth the effort if you can even FIND cables that long. You might have to make your own - if you do, as I mentioned earlier, get the LOWEST capacitance cable you can find and it may just work... Steve

[BigKahuna]

great post, Steve
thanks!!

[subtractor]

I use a motu midi expressxt interface. Put it close to the intruments and use a very long usb cable to the pc.

[djc]

Good info Steve