I believe some cheaper USB-MIDI cables drop SysEx messages. I have the Roland cable myself though and it works well.

Cheap USB/MIDI cables often don't contain an opto-coupler, not even a switching transistor (pull-up/down) .

They do transmit data by using the controller chip's power from its pin.
A simple resistor is all that's protecting that pin.

Source: http://www.arvydas.co.uk/2013/07/cheap-usb-mi … ay-be-required/

That's very un-elegant and causes a lot of trouble - because MIDI, electrically, is a current loop.
With the exception of the WaveBlaster header, which is just a normal serial port running at 5v level. 🙂

The simplest solution, I'm afraid, is to fix these 5vbles by manually installing an opto-coupler.
Their PCBs often have a provision to add it back.

And yes, there might be a problem with missing MIDI notes.
I've had missing messages myself when using DOSBox on a Pi.
Though I don't know for sure if it was the cable, Raspbian or the circuit of my Mt32-pi build. 🤷‍♂️

Even if you add the optocoupler the chip might not be able to handle fast sysex.
Better budget options are getting a second hand m-audio midisport uno or Roland UM-1S. If you get this old roland cable you will have to edit the drivers for windows.

The best way is to get a Roland UM-One Mk2.

Thanks everyone, you gave me a lot to think about. I had not considered the lack of data (inc. sysex) with cheaper models.

This is what I currently have: https://m-audio.com/products/view/midisport-2 … versary-edition . It worked fine "back in the day" but I see most recent drivers are from 2013. I may yet give it a go, despite the amount of cables that it needs

Otherwise, if I understand correctly, the Roland UM-One Mk2 might be the best option to ensure no compatibility issues. I see however it's gone up in price in the last year or so ( https://www.amazon.co.uk/Roland-UM-ONE-mk2-MI … UN50/ref=sr_1_1? ) unless someone can recommend a better place to hunt for one?

I've been using an M-Audio Uno 1x1 USB MIDI interface (https://www.sweetwater.com/store/detail/Uno--m-audio-uno).

I've had zero issues using it with all sorts of MIDI modules including the MT-32.

pedrorq wrote on 2022-05-04, 14:54:

Otherwise, if I understand correctly, the Roland UM-One Mk2 might be the best option to ensure no compatibility issues. I see however it's gone up in price in the last year or so ( https://www.amazon.co.uk/Roland-UM-ONE-mk2-MI … UN50/ref=sr_1_1? ) unless someone can recommend a better place to hunt for one?

I use the UM-ONE MK2 and haven't had any issues with it on my MT-32 through Dosbox. Some of the better pricing on some of these items is to check Reverb.com. I believe that is where I got my UM-One originally several years back.

https://reverb.com/p/roland-um-one-mk2-usb-midi-interface