The slightly more modern and stable alternative to Apple Midi Manager is called OMS. It may require System 7, I can't recall.
The QY10 was my first piece of music hardware
If it, like some 80s-90s gear, actually has a mini-DIN serial port as well as MIDI, you can in fact plug it straight into a Mac without a MIDI converter. If you like the sound of that, keep an eye out for a Roland Sound Canvas or Roland PMA-5. You can also find some older Roland keyboard/synths with the Mac serial plug.
There are schematics floating around for building your own Mac MIDI converters - they're pretty simple, and you could probably bodge one up in half an hour once you have the parts.
The QY10 was my first piece of music hardware
If it, like some 80s-90s gear, actually has a mini-DIN serial port as well as MIDI, you can in fact plug it straight into a Mac without a MIDI converter. If you like the sound of that, keep an eye out for a Roland Sound Canvas or Roland PMA-5. You can also find some older Roland keyboard/synths with the Mac serial plug.There are schematics floating around for building your own Mac MIDI converters - they're pretty simple, and you could probably bodge one up in half an hour once you have the parts.