Don't Pull That Trigger!
A lot has happened in the e-drum world over the last 30-plus years. Companies and products have come and gone, and in many cases, come again. Alternate Mode, Pearl, Roland, and Yamaha – all key initial players in the world of electronic drums – have continued to consistently create innovative products. They’ve made new sound modules, created new ways to manipulate sounds using a drummer’s performance, as well as made strides in pad design, using new materials and clever mechanics to make e-drums more playable and responsive than ever. Even with all this innovation, getting a pad or drum trigger to respond as wanted is still somewhat of a mystery. I’m not saying that the jokes about drummers are true, it’s just that balancing all the trigger settings within a drum module requires a bit of understanding.
Further complicating things, almost every situation is unique. Pads and acoustic drum triggers are susceptible to many external influences: pad or trigger type, type of pad mount, stage volume, and drum type and tuning (in the case of acoustic drum triggers).
The Mechanics Of Triggering
The chain of events needed to hit a pad and make a drum module play a sound is simple (also assume triggered acoustic drum when you see the word “pad”):
1) Hit the pad
2) Drum module trigger input reads the trigger waveform
3) The drum module interprets the trigger waveform and sends the assigned sound to the audio output(s)
The vast majority of pads and acoustic triggers rely on piezo technology to make them work. A piezo is a crystal that has the property of producing voltage when it is put in motion. In our case, we put the piezo in motion by striking something to which it’s attached or coupled. This could be a rigid plate in a pad, or a drumhead of some kind. Because a piezo is very fragile, striking it directly will destroy it rather quickly. Because of this, many clever ways have been devised and patented to protect the piezo, while at the same time offering adequate triggering performance. In addition to piezos, there is also increasing use of FSR technology – force-sensing resistors – in pads and acoustic triggering, most notably by Aquarian in its inHead drumheads and onHead pads. This technology was pioneered for drums by KAT, and Alternate Mode, its successor. A bit more on FSR later.
When a pad is hit, a small amount of voltage is produced and sent to trigger input of the drum module. The harder the pad is hit, the larger the amount of voltage is produced; usually maxing out at around five volts. The volume of the sound the drum module plays is directly related to the voltage produced by the pad. The higher the voltage, the louder the sound produced. All fairly simple.
When captured and viewed, this voltage has a shape, let’s call it the “trigger waveform.” The trigger waveform will be expressed in voltage over time. The height of this waveform is referred to as its amplitude; the higher the voltage, the larger the amplitude. (Fig. 1) It’s important to understand that the length of the trigger waveform directly relates to decay of the actual sound or vibration of the pad or triggered acoustic drum. In the real world, a triggered acoustic floor tom will have a long decay, while a triggered snare drum and pad will have much shorter decay. (Fig. 2)
Trigger settings inside the drum module are used to manipulate how the trigger waveform is interpreted. As a rule of thumb, short waveforms are much easier to interpret than long waveforms. This is because longer waveforms can have secondary trigger spikes. These secondary spikes, which most often occur when triggering from acoustic drums, are difficult for the module to interpret. The module has to determine if a waveform’s secondary spike is an actual restrike of the drum, or just a secondary trigger (false or double trigger) occurring within the decay of the drum. The faster a drum is played, especially those with a long decay, the harder this interpretation becomes. This often results in missed notes or double triggering.
The good news is that when using a manufacturer’s stock pad and module configurations, the work is already done for you – little or no tweaking should be needed. The fun starts when non-stock configurations are used ¬– especially those mixing and matching pads, triggers, and modules from various manufacturers. In these situations, tweaking of trigger settings will definitely be needed! That said, all the modules from Alternate Mode, Pearl, Roland, and Yamaha – which we’ll be looking at here – handle triggering amazingly well.