Hi Rich,

Thanks for the question. Both items allow you to connect an electronic musical instrument via Bluetooth to a capable smart device sending MIDI information bi-directionally. You can connect to iOS devices (iPhone, iPad, etc) As a Motif XF owner you could choose either device (and thus the question): Which one?

I guess I better explain why both exist. I'm not sure of the exact number of unique products that Yamaha makes (it boggles the mind) but believe it or not, not all come with standard 5-pin MIDI jacks any more. At the lower end of the price scale (where every dollar counts to meet a price point) it might be excessive to include both USB ports for MIDI and standard 5-pin MIDI IN/OUT/THRU ports. After all some of the entry level keyboards may in fact, never be connected to another keyboard or module via standard 5-pin MIDI jacks, and are far more likely to be connected to a laptop or desktop computer (nowadays). So because there are many products that *only* have the USB "To Host" port on the back, the UD-BT01 exists. (USB Device-BlueTooth 01).

All of the synthesizers from Yamaha feature both the USB "To Host" port and the standard 5-pin MIDI jacks because both are likely to be used (maybe not always at the same time, but certainly often at the same time: the MX, MOX/MOXF, S-XS, and Motif-series all feature both types of connectivity and can use both simultaneously... As when you are connected to the computer via USB and using the 5-pin jacks to interface with an external keyboard or module. All of these synths can act as a MIDI interface for an external device allowing the external device to send its MIDi messages through the synth on to the computer.

The MD-BT01 (MIDI Device BlueTooth 01) connects to the 5-pin IN/OUT jacks of your instrument and let's you broadcast wirelessly from there for MIDI communication (up to 10 meters). Functionally the same as the other unit... Both allow your iPad to be connected wirelessly to your keyboard while still being connected to a charger or A/C (so you never have to worry about your mobile device running out of juice during a creative session.

There is a nice Compatibility Chart that shows which Type of ports are available on the various devices. You'll notice that all of the synthesizers can actually use either one. If you own a reface YC/CP/CS/DX and want total mobility (because you're sitting poolside or in the park being creative) far from any power source, the MD-BT01 clearly has an advantage. It is able to draw the power it needs to function from the instrument via the 5-pin MIDI jacks of the instrument. The UD-BT01 must be adapted and plugged into an A/C power source in order to function. So that is a huge difference for those wishing to be totally mobile.

The MD-BT01 is nifty, neat, less to setup, and basically disappears when working -simply plugs the MIDI OUT to MIDI IN...
The UD-BT01 solves the wireless connectivity between instrument and smart device for those instruments that do not have 5-pin DIN MIDI ports to connect to... So as a Motif XF owner (we assume so because you posted in this forum heading) you'd probably opt for the MD-BT01.

Hope that makes sense. Thanks for the question.

This is why you are the "go to" professional. Asked and answered better than I expected. New insight into potential uses. As for me, the "MD" will suit my Bluetooth appetite.

Many thanks Phil