Why does iOS GarageBand's MIDI sound disappear?

Riku7

macrumors regular
Original poster
Feb 18, 2014
124
17
Oh really hot days I can't run my main Mac at all so in order to not spend days or even weeks completely unproductive, I'd like my old iPad to provide sound to a MIDI controller keyboard. I don't dream of seriously producing music on an iPad, I'd be happy with just having sound so I can do something.

I have the camera connection kit which turns the iPad's connection into a female USB port. I also have a MIDI cable with MIDI in/out at one end and USB male at the other. Fine, now this connects the iPad to the keyboard. Because (the compact keyboard that I can actually move around easily) is bus-powered and an iPad can't provide that power, I'm using the keyboard's USB port to get power from a wall socket.
So far, so good: The keyboard's display lights up, the iPad's GarageBand recognizes it and I can play the GarageBand instruments. However, after a few minutes, it stops making sound and I have to unplug and replug the MIDI cable for it to respond again. At first I thought that it was happening because I hadn't triggered any MIDI notes for a while, but I can now confirm that it's not about inactivity, but the time starts running from the first moment you plug it in. This behavior seems to be very consistent and without exceptions.

Is this a known issue and is there anything I could do about it?
 

Wando64

macrumors 6502a
Jul 11, 2013
748
827
It is not a known behaviour and it shouldn't happen.
I can only imagine it could have something to do with the USB to MIDI cable that you are using.
My recommendation would be to either:

A. Plug both iPad and Keyboard into a powered USB hub, and use MIDI over USB to communicate between the two
OR
B. Plug the iPad into a USB audio interface (depending on the type of iPad you have, this might still require going through a powered hub) and connect the keyboard to the MIDI output of the audio interface.

I regularly use both solutions and they work fine.
 

Riku7

macrumors regular
Original poster
Feb 18, 2014
124
17
I wanted to avoid trying any big investments because the fact is that it's an old iPad which might not have that much life ahead of it anyway, and a new iPad is not on my shopping list anytime soon. So instead, I got a lightning to USB converter for my modern-ish iPhone and tested the same setup with the keyboard. My first impression is that it no longer drops the MIDI connection, so I'm suspecting the fault to either be the iPad's port, its operating system, or its camera connection kit, rather than the M-Audio MIDI IN/OUT to USB wire or the MIDI controller keyboard. The downside is that the small display of a phone is an absolute pain to use (and this is the only context where I think that a smart phone's display is not small enough!) and I think it consumes the battery in pretty much no time. So we come to:

A. Plug both iPad and Keyboard into a powered USB hub, and use MIDI over USB to communicate between the two
I never knew that devices plugged into the same USB Hub could talk to each other via the hub. Is this normal for all hubs and they do it without any setup, or is it a special feature that only some can do? So would this simultaneously power the keyboard, keep the phone or tablet charged, as well as let them communicate?
 

Wando64

macrumors 6502a
Jul 11, 2013
748
827
I wanted to avoid trying any big investments because the fact is that it's an old iPad which might not have that much life ahead of it anyway, and a new iPad is not on my shopping list anytime soon. So instead, I got a lightning to USB converter for my modern-ish iPhone and tested the same setup with the keyboard. My first impression is that it no longer drops the MIDI connection, so I'm suspecting the fault to either be the iPad's port, its operating system, or its camera connection kit, rather than the M-Audio MIDI IN/OUT to USB wire or the MIDI controller keyboard. The downside is that the small display of a phone is an absolute pain to use (and this is the only context where I think that a smart phone's display is not small enough!) and I think it consumes the battery in pretty much no time. So we come to:



I never knew that devices plugged into the same USB Hub could talk to each other via the hub. Is this normal for all hubs and they do it without any setup, or is it a special feature that only some can do? So would this simultaneously power the keyboard, keep the phone or tablet charged, as well as let them communicate?
The only reason you need the Powered hub is because you said the keyboard is USB powered and an “old iPad” wouldn’t be able to provide the necessary power over USB. “Devices plugged into the same hub” don’t talk to one another, but they talk to the the port that the hub is expanding i.e. your iPad. Finally, the hub will not power the port it is expanding i.e. the iPad, but it will provide power to the devices connected At the other end.
 

Riku7

macrumors regular
Original poster
Feb 18, 2014
124
17
The only reason you need the Powered hub is because you said the keyboard is USB powered and an “old iPad” wouldn’t be able to provide the necessary power over USB. “Devices plugged into the same hub” don’t talk to one another, but they talk to the the port that the hub is expanding i.e. your iPad. Finally, the hub will not power the port it is expanding i.e. the iPad, but it will provide power to the devices connected At the other end.
But my keyboard was being powered already: It had its USB cord going directly to a power supply unit in a wall socket. I can also replace the power supply unit with a power bank. But since that occupies the keyboard's only USB port, that's why I used its MIDI IN/OUT sockets instead, to get the connection to the iPad. I had already talked to some people on different forum, about powering this keyboard in other means than the USB bus power itself, because you can only provide power to this via the USB port, but depending on your other device, MIDI can either be transmitted via USB or MIDI IN/OUT.
 

Wando64

macrumors 6502a
Jul 11, 2013
748
827
But my keyboard was being powered already: It had its USB cord going directly to a power supply unit in a wall socket. I can also replace the power supply unit with a power bank. But since that occupies the keyboard's only USB port, that's why I used its MIDI IN/OUT sockets instead, to get the connection to the iPad. I had already talked to some people on different forum, about powering this keyboard in other means than the USB bus power itself, because you can only provide power to this via the USB port, but depending on your other device, MIDI can either be transmitted via USB or MIDI IN/OUT.
We are saying the same thing.
I am suggesting you could use MIDI over USB and, because you need to power the keyboard over USB too, you will need to use a powered hub so the power can be passed from the HUB to the keyboard *as well as* the MIDI data.
- - Post merged: - -

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Riku7

macrumors regular
Original poster
Feb 18, 2014
124
17
I am suggesting you could use MIDI over USB and, because you need to power the keyboard over USB too, you will need to use a powered hub so the power can be passed from the HUB to the keyboard *as well as* the MIDI data.
Oh! Sorry, I somehow imagined every device merely being 'equal client devices' and forgot about this topological detail of the male USB connector having a special role. I see. In this setup though, the iPad can't be charged simultaneously either, right? It's probably impossible.
 

Wando64

macrumors 6502a
Jul 11, 2013
748
827
Oh! Sorry, I somehow imagined every device merely being 'equal client devices' and forgot about this topological detail of the male USB connector having a special role. I see. In this setup though, the iPad can't be charged simultaneously either, right? It's probably impossible.
When I had a lighting port iPad I managed to get it to charge by using a third party connector that had both a USB female port and a lighting female port. I could attach the hub to the USB and the normal charger to the lightning.
However, it is pot luck to find one of these connectors that work as advertised. They all seem to be coming from China.
 
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