If you want to connect your USB keyboard to your MIDI gear without a computer, this little box might fit the bill...
There are plenty of MIDI interfaces that allow instruments and effects equipped with five-pin DIN MIDI sockets to communicate with a computer via USB, but what do you do if you have a USB-only MIDI keyboard that you need to integrate into the five-pin DIN MIDI world without involving a computer? Simple: providing your USB controller keyboard is 'class compliant' so that it can communicate via USB with no additional driver software, the Kenton MIDI USB Host will do the trick. The physical implementation couldn't be simpler: it's a small aluminium box (110 x 55 x 32 mm) with MIDI In and MIDI Out sockets, a USB Type A socket and a power connector for the included regulated 5V power supply. A small LED shows when the unit is powered and active. Your keyboard plugs into the USB port, and there you have it — old-school MIDI In and Out ports. MIDI data received at the MIDI In socket will be sent to the USB device, while MIDI data received from the USB device will be sent to the MIDI Out socket.
The manufacturers recommend that the USB connection be made before powering up. If the power is switched on with nothing plugged into the USB socket, the LED will flash. If it doesn't stop flashing when you hot-plug the USB device, you need to power down, plug in the USB device then try again. Note that some USB keyboards can be set either to Class Compliant (or generic) mode or to an advanced driver setting. The device must be in Class Compliant mode to work with the Kenton MIDI USB Host.
Kenton advise that most Edirol products have the advanced setting on by default, so if you have one, you'll need to refer to the manual to see how to switch back to Class Compliant mode. Also check for software updates if you have a Novation controller or keyboard, to see that you have the latest firmware update, which should work with the Kenton MIDI USB Host. (Note that this may only apply to the Remote Audio, LE or SL series, and not the 25/37 models.)
It is also essential to use the regulated PSU that comes with the MIDI USB Host, to avoid passing on excessive voltage levels to the connected USB device. An external USB device can be powered from the Kenton MIDI USB Host up to a maximum of 500mA. If the input voltage rises above 6.5 Volts for any reason, such as connecting the wrong PSU, the power will be shut off and you'll have to wait around a minute for the thermal trip to reset.
I tried the unit with my own Edirol PCR300 keyboard and, sure enough, I had to switch off the advanced driver mode first, but having done that, it just worked. I dug out my ancient MIDI analyser, hooked it up and checked that the right type of MIDI data was being sent for all the keys, knobs and buttons, and all the right LEDs lit up. So, in summary, this device 'does exactly what it says on the tin'.
If you need this facility, the Kenton MIDI USB Host offers a solution, but it's imperative that your USB keyboard can work in Class Compliant mode.
I'm not aware of any direct alternatives, although you can probably buy a used MIDI keyboard for around the same price.