I had one that would stop passing note data if you sent a program change while sending CCs. At the end of the day, they’re a €10 midi interface, you can’t expect them to be perfect forever. I still use that wonky one if I want to play round in the dining room 
those cheapo cables work sometimes for some things … but have problems just like you experience.
Either try the Roland UM-ONE mk2 (Roland - UM-ONE mk2 | USB MIDI-Interface) which is a lot better or an audio interface / proper midi device.
I have a decent midi interface, that’s not my problem or what I’m asking. Both of these cables work perfectly fine, I use them all the time with the MPC and the iPad. My question is about why the joined cables do not pass data through the adapters. Both cables and the adapters all work perfectly individually. I’m guessing it an impedance/electrical issue because Midi cables do carry a small charge.
I guess this is just going to end up a ‘don’t use Chinese midi cables’ thread. 
I’m perfectly happy with them, I just want to know why joining them together fails. My mission was to make a USB A to USB A midi cable.
I’m hoping someone who understands the electrical aspect will answer.
Good luck then! 
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It would be really handy if it worked and save some complexity, it’s not the end of the world and don’t have much hope now but I really want to know why it should fail, it’s just connecting 2 sets of midi cables at the end of the day.
Might be a physical connectivity issue, send data through one end and see what fails to come out of the active pins.
Cheap works
Cheap to cheap doesnt
Good to cheap does
Might be some minor DIN flaws that accrue together where careful fitting is present in your interface, synths, and better cables.
I don’t think this can possibly work. You have a USB-A connection at both ends, that can’t work. The A end of a usb connection is the “host” which controls the “device” at the other end. You can’t connect A to A because you would have host talking to host, and they both want to be in charge. That’s why you can’t get USB-A to USB-A cables, they always have B or mini-B or micro-B at one end.
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No it isn’t.
Midi cables just contain wires, no smarts. Each pin is connected to another pin by a wire. But the USB protocol is much more “clever” and isn’t just a case of connecting the corresponding pins via some wires. The two ends of the usb connection have to agree to talk the USB protocol, and one end agrees to act as host and one end agrees to act as device. You can’t have two hosts communicating.
Edit: though I guess it could work in theory, since the two hosts don’t actually see each other as usb hosts, just as dumb midi devices. Hmm.
Edit 2: now I’m really confused whether this can work… I should stick to the beer thread when I’m this drunk at midnight.
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Yeah, I don’t see how the USB has anything to do with it, both are converting to Midi. I’ve just had it all out again and tried every test/combination just to be fully certain there’s no physical defects causing it. I’ve also tested on a MacBook instead of the iPad and it’s the same.
I’ve also tried using MPC USB Midi out to Virus TI Midi Din In and the used the second USB cable from the Thru port to the iPad and that works as expected passing the midi through. Basically using the TI instead of the adapter. I’ll hopefully get my Kenton thru box back to test in the next week, although I’d want something passive for it to be useful.
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It seems plausible that your adapters were designed with the assumption that there would be a fully functional MIDI device on the other end, and then cut some corners to save costs or design time.
The E-Mu branded cable I mentioned over in the X.05 thread is apparently still made with the good stuff, so if your goal is to have a USB-USB MIDI null modem setup, then you might try a pair of those. The E-Mu passes sysex, which a lot of cheap cables manage to screw up. If they paid more attention to detail in the software, maybe they didn’t cut as many corners in the hardware.
Maybe it’s a MIDI loopback issue? Does it work with just one of the plugs connected (ie. sending MIDI from MPC to ipad?
Any reason why you’re not just using one USB-MIDI cable from the ipad to the MPC’s DIN sockets? Or a USB-A cable from ipad to the USB-B input on the MPC?
Yeah these cables don’t do sysex, but they are honestly flawless outside of that, I’ve used them a lot over the years because they are convenient to move around rather than the hassle of an interface.
Tbh, it’s not something I want to spend a lot of money on, I just had the cables and thought I’d get some adapters and give it a try.
I’ve been reading up on it a bit and it seems that midi outs send 3-5v and inputs should be passive. Perhaps these cables aren’t but then you’d expect the midi ins wouldn’t work at all if that was the issue.
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I’ve only been testing the midi in most of the time, they have midi activity indicators on them. Yeah the cables work great from both devices. I usually use the midi ports to iPad usb, but it ties up the ports, it would be great to use the iPad via USB. It’s not the end of the world, I’d just like to know why it it doesn’t work.
As for the A to B cable, I don’t think that would work would it? I’ve seen people complaining about the ipad not being class compliant for midi and so I’ve never tried. I’ll go and try it now though!
EDIT: No sadly neither side sees anything, I don’t think either of them are class compliant…
I mean you’ve tried everything else, why not? Even if it’s not the solution you want it’ll help isolate what the problem’s not. See if that extra data point shakes anything loose.
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I have a feeling it will work with the Kenton and it’s maybe a voltage issue, and it needs something powered in the middle to reamp the signal, considering that the virus TI as a thru box worked. I’ll maybe pick up another brand of cable at some point too to see if it will change anything.
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I’m spatially retarded but actually it might be when using one of those din busses the pin numbers don’t align correctly because the pin numbering on a female midi connector are mirrored but in this case it’s just a throughput so pin 1 on cable A is going to pin 5 on cable B and vice versa. Very ineloquently worded, sorry about that.
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Output to input should be fine though, it’s the expected use; same as going from a keyboard’s MIDI out to an interface’s MIDI in.
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It works with 1 cable and a midi lead plugged into it though.
I’ve done this exact thing with 2x m-audio unos and it worked perfectly. Have you tried changing your connections? Gotta make sure your ins and outs are flipped. (He says from experience lol)
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Yeah, I am 100% sure of everything, had 2 lengthy sessions of testing and trying all components individually and together with multiple systems. I’ve been dealing with midi since 1990, so it’s not down to inexperience etc…
Really good to know it works with Unos though! At least I know the idea is sound, it’s just the cables that can’t do it. Thanks for letting me know, that’s the sort of answer I’ve been hoping for
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