For percussion (drums) tracks, the performance panel looks a bit different, of necessity.
The reason for the difference is that percussion tracks select different percussion instruments by which key is pressed, and there is a different instrument for each half-step in a 12-tone chromatic scale. Because of this, all of the intelligence built into the keyboard for doing transposition, and knowing whether to play a black key or a white key, cannot apply.
As a result of this, the staff-lines & keyboard diagram is very different for percussion tracks, as we see below:
There are a few items of note in the top row of MIDI controls.
First, in this case, the MIDI channel is 10. The synthesizer I was using is the hardware synthesizer on the Soundblaster 'Live!' sound card. With this synthesizer, per the General MIDI standard, track 10 is a percussion track. For other synthesizers (such as Qsynth), selecting bank “1:0” (actually bank 128) is used to designate a percussion track (which I have also selected above). But for the emu10k1 chip's synthesizer implementation on the Soundblaster 'Live!' card, if it's channel 10, it's a percussion track.
Also take note that the base octave is “3”, and the transpose value is “1-Down”. I will explain the reason for this later.
Notice above, that the keyboard diagram is still the same. You still play just the 'white key' note of the keyboard, but notice on the left, these keys line up with each of the various percussion instruments. There are no staff-lines, nor is there any key-signature.
The mapping of keys to percussion instruments is per the General MIDI standard. If you import your instrument definitions from a Rosegarden bank definition, you can specify a different instrument key-mapping. If the instrument definitions are imported from a soundfont, the built-in General MIDI standard mappings (above) are used.
In the diagram above, the number on the far-left is an actual MIDI note number. MIDI notes range from 0 (the first note of octave 0) to 127 (the highest note that can be specified over a MIDI interface. I very much doubt that there is a keyboard with a key for every possible MIDI note (all 128 of them). A full piano keyboard has 88 keys, so the MIDI standard allows 40 notes below/above those used in a piano keyboard.
Since a typical synthesizer has 61 keys (5 octaves), and originally it was not so easy to change the octave transposition, it made no sense to start defining percussion instruments at MIDI note 0. To accommodate the keyboards out in the market, the General MIDI standard starts defining percussion instruments at MIDI note 35.
To fit with this (and allow a single keyboard note per percussion instrument), the KeyMusician keyboard sets the base octave to “3”, and the Transpose to 1-Down, which puts the first percussion instrument at the bottom of the diagram, and even leaves room for an additional one at the top of the diagram. If you use a different percussion key-mapping, you may want to vary the base octave and transpose values to fit it.
In the example above, I was playing (simultaneously) instrument 47, the Low-Mid Tom, and instrument 49, the Crash Cymbal 1.
All of the MIDI controls (and buttons) work the same as in melodic instrument panels. You can use the volume slider to fade out a drum roll the same way you use it to fade out a long trumpet note. The exception to this, is that I have not observed the “Sustain” button to have any effect on a percussion track.
The “Instrument” drop-box on percussion banks lets you select the type of drum kit you want to use. There are kits for rock, jazz, orchestra – you name it. And they do change the sounds made by the percussion instruments.
The final thing to take note of, is the “Percussion” check-box. If this is checked, you get the percussion-unique keyboard/instrument display shown above. You can actually use this on a melodic MIDI instrument, and it will dutifully play it. If you do this, the keyboard notes you play will be the notes of a chromatic (12-tone) scale (but with an unusual transpose setting), which might be useful in rare cases.
Normally, the keyboard keys play the notes of a key-signature-specific scale, which has 7 tones in it. Here, it plays the 12 tones of a chromatic scale.
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