All the music data files are based on GM standard SMF(Standard MIDI File, *.mid) format-0.
The volume data (CC#7) of each part is set to maximum. If you want to make some particular part louder, download the SMF, and reduce the volume data of the other parts using proper sequence software.
Download free if you are going to use these SMF's for the purpose of the music practice or the music research. Contact me if you want them for commercial purpose.
*Since I trimmed the data of these SMF's in this site to reproduce through YAMAHA:DOU-10, it will bring you the best result, but it is too old to get. So I recommend Mid Radio: freeware SMF player application with software tone generator.
1. for orchestral practice
The independent MIDI part is given to each part of the score.
The tempo of each tune is set to proper as I imagine.
The title of the tunes, in which choir is used, are indicated in bold letters.
2. for choral practice
The parts of the same instruments are sometimes put into one MIDI part.
The slower tempo is set to the tune which tempo is fast usually.
When you click the title of the tune, you can access the data, in which the pan of the choral parts are set to left, and the pan of the orchestral parts are set to right.
When you click the choir part, you can access the data, in which that part is set louder and the pan to center, the pan of the other choral parts are set to left, and the pan of the orchestral parts are set to right.
In the case of Motets (BWV225-230)
The same format data as "for orchestral practice" when you click the title of the tune, and the volume-up version as "for choral practice" when you click the choir part. The instrumental organizations are refered to the list of the instrumental sheets from Baerenreiter.