Now Igor, it’s onto the brain! You could pick up a brain for anywhere between $150 used on eBay, to $2,100 new out of the box. It really depends on how much flexibility you want and what your basic requirements are. If you were seeking a basic module to simply trigger sounds without a lot of extras, then a pre-owned older model, say the Alesis D4, would work just fine. But if you’re looking for a fully featured module with loops, effects, a metronome, a plethora of preset kits, an epic library of sounds, and flexible user-defined parameters, then something like the Roland TD-20 may be more up your alley.
Companies like Roland, Alesis, Yamaha, and ddrum offer a variety of drum modules to imbue your Franken-kit with life. A good comparison of brains can be found at drumjunction.com, hartdynamics.com, and drumbalaya.com. Things you should be looking at include the number of trigger inputs, variable hi-hat nuance control for a natural hi-hat sound, a good library of sounds, compatibility with various electronic kits, and whatever extras you may want, such as a metronome and built-in sequencer for programming loops to play along to.
If you want greater flexibility, consider getting a brain that features stereo inputs for dual triggering off of one jack. You could make multiple triggers on one sound source work with mono inputs, but you could be limited depending on the number of inputs. Most of the available drum modules today have a separate hi-hat input to handle the variations.
There you have it, a basic foundation from which to start building your own electronic drum set. Of course, there are many different approaches and variations on what’s presented here, depending on how much time and money you want to spend and what you want to achieve. Online resources and forums for DIY electronic drum builders abound. You could create an entire kit, or even just build a few pads to enhance your acoustic setup. Hey, it’s your monster.