I play a Roland TD-30K drum kit and have been working to extend what can be done with this incredible piece of technology for quite some time now. A sort of holy grail I have been aiming for is the ability to support others in the group I play with by being able to trigger melodic instrument parts using percussive MIDI signals. I have extended my ability to trigger sounds by adding 4 Roland BT-1 bar triggers which I use to occupy the four Aux channels in the TD-30 module. The thought is to be able to use them -- or other triggers/MIDI controllers reasonably able to be activated by drum sticks -- to trigger different chords or other melodic elements of the song to add dynamics to a live performance without using loops or backing tracks.
The challenges I seem to continue running into are as follows:
First, I have found that though MIDI controllers used to control melodic instruments (such as a MIDI keyboard) are often moderately well-suited to playing percussive parts, the reverse is not necessarily the case. For example, the sustain portion of a sound's volume envelope is difficult to manage when triggered with a transient MIDI signal. The triggered melodic notes would all need to be the same length unless a sequencer is used to set up a specific sequence of MIDI note lengths in advance. A simpler way to go would be to simply have the MIDI controller latch one note before proceeding to the second (useful for, say, an organ pad for example), but I have had difficulty finding MIDI controllers that are percussive in nature (and which would not require me to remove my hands from the drum sticks & drum/percussion kit) which have latching functionality, and whatever software plugin, etc. being used to generate the sound may or may not have a latching feature either.
Given that I would like to use specific instrument patches for different songs, I would like to be able to control switching between control of melodic instruments being triggered by MIDI on the fly similarly to how different drum patches can be switched between in the TD-30 itself.
The two challenges above seem like they could be feasibly controlled by some sort of MIDI interface that would act as an intermediary between the hardware triggering the initial MIDI notes and the software that receives them. If custom routing of MIDI, and MIDI-triggered changes in the configuration of which were controllable by this interface it seems like the above could be achieved. Is anyone aware of such a thing, or does anyone have any other suggestions which might pose some other solutions?