MIDI cable question.

[Guest scott cs.]

is it possible to buy a MIDI to USB cable or will i have to make my own/buy an interface?

[skuzzlebutt]

is it possible to buy a MIDI to USB cable or will i have to make my own/buy an interface?

yep there's a pile of people make them.... one i use is made by edirol (UM-1)'bout 50 quid but works fine enough and easy enough to install...

[skuzzlebutt]

And here's the link.

http://www.sub.co.uk/index.php?sec=proddetails&pcode=UM-1EX#

Note that the blurb describes this as an interface - it probably has some inline circuitry involved. I would be very surprised if you could simply connect a USB plug and a 5 pin DIN to either end of a cable' date=' and I wouldn't recommend that you try...[/quote']

you definitely cannot...for this to work the USB and midi data standards would have to be the same, ie speed, lines, data formats, protocols expected by both receivers etc and they most certainly are not, USB is way quicker for a kick off....also midi usually uses an optocoupling interface which, at least for most mature products the speed of USB would exceed the optocouplers capabilities...(i'd bet the optocouplers rise and fall times are larger than a clock period on USB)

the um1 does have inline circuitry to realise the required interface

another thing i forgot to mention is that the edirol unit has pretty reasonable data latency, as far as i've noticed which again makes it reasonably attractive for such an application... however follw the driver instructions to the letter would be another tip...if you decide to take the um1 route...

[skuzzlebutt]

I did not know that. Opto-isolators (same thing) are used to isolate circuits of different voltages - is that the case here? Or are they being used to eliminate noise / voltage transients that could bugger up the data?

at a guess, i suppose somebody figured that musos are too fuckwitted not to have ground loops at different potentials.... so optoisolating everything negates problems associated with differing grounds ie noise biases etc...if you think about it any ac/dc device may have a floating ground/ grounded 0volts or some arbitrary ground....strap 'em all together via the serial data bus and a whole heap of nonsense can occur.... also bear in mind that midi has been around since the early 70's so i guess it made a lot f sense to optocouple...

i've got a book somewhere about all this shit...if i dig it out i'll see if there is any explaination justifying this feature..

[Guest Main Agent]

i suppose somebody figured that musos are too fuckwitted

Never......?(

[Stripey]

I don't understand what the problem is. If you want a USB midi interface, just go and buy one, they are not expensive. If you have a PC or laptop which has a joystick port, then all you need is a midi cable suited to it.

[Compuphonic]

at a guess' date=' i suppose somebody figured that musos are too fuckwitted not to have ground loops at different potentials.... so optoisolating everything negates problems associated with differing grounds ie noise biases etc...if you think about it any ac/dc device may have a floating ground/ grounded 0volts or some arbitrary ground....strap 'em all together via the serial data bus and a whole heap of nonsense can occur.... also bear in mind that midi has been around since the early 70's so i guess it made a lot f sense to optocouple...

i've got a book somewhere about all this shit...if i dig it out i'll see if there is any explaination justifying this feature..[/quote']

Optocouplers are a requirement of the midi spec. Best ask Dave Smith why he designed them there, but they make a lot of sense to me.

Midi has been around since the early '80s - think it was 1982 if I remember correctly.

As for USB to midi interfaces there are several on the market. Turnkey were selling off Emagic ones for 20 recently, MOTU have several as do to the other names already mentioned in this thread.