The MusicWeaver 1.3 should run fine under BeOS R5 -- except for one little thing...! Trying to use the internal synth "out of the box" will crash it.
The trivial reason for this is that the internal synth (not the MusicWeaver itself) is looking for a file of instruments named 'big_synth.sy' in /boot/beos/etc/synth, but it doesn't exist -- under that name.
Be have promised a fix/patch for this, but in the meantime applying your own cure is easy -- create a link from 'big_synth.sy' to 'Patches111.hsb' in the above folder. Probably the simplest method is to open a Terminal and do:
cd /boot/beos/etc/synth ln -s Patches111.hsb big_synth.syThe Synth should work then. Only the 'WvrSynth' module of the MusicWeaver is affected, by the way, so if you just use external MIDI, you won't need the fix.