Don’t Pull That Trigger!

The Skinny:

Pads are fairly easy to make trigger accurately and precisely. Piezo-based acoustic triggers are much more difficult to make perform well. Pads and short acoustic sounds are much easier to make trigger well than acoustic sounds with long decays.

Terminology
The first order of business is to cover some basic triggering terminology. Please note that there are a few differences between what each company calls the same setting. If there is an asterisk by a term, refer to Fig. 3 for the differences.

Amplitude
The height of a trigger waveform, measured in volts.

Crosstalk*
The vibration of the drum or pad being struck causing another trigger input to sound. This can be caused by sympathetic and mechanical vibrations from adjacent pads, or external loud sounds like stage monitors.

Double Trigger
One or more sounds sounding just after the initial (intended) pad or trigger hit.

Headroom*
A setting, related to mask time, that helps reduce false and double triggering due to additional peaks after the waveform’s initial peak, or trigger spike.

Mask Time*
The amount of time a module’s trigger input waits before it will react to another trigger signal. This setting helps filter out (mask) double triggering in the first 1-60ms (milliseconds) after a trigger signal is recognized by the trigger input. It is generally measured in milliseconds.

Milliseconds
A measurement of time. One-second equals 1000 milliseconds. For reference, in air, sound travels at the rate of about one foot per millisecond.

Scan Time*
The amount of time after receiving a trigger signal that a sound module waits before reading the waveform amplitude to determine the volume (velocity) of a sound – measured in milliseconds.

Sensitivity*
A trigger setting used to balance out the varying voltage output levels of different acoustic triggers and pads.

Threshold*
The point below which a trigger waveform will not be recognized by a drum module’s trigger input.

Velocity Curve*
A setting used to alter how a drum module’s sound volume changes in relation to user input.

Waveform, Trigger Waveform
The representation of the voltage output of a drum trigger – shown in amplitude over time.

terminology

Fig. 3

Understanding Pad Types:

Rubber and Silicone, Mesh Heads, and FSR

Rubber and silicone pads essentially come in three types: single trigger, dual trigger, and three-way trigger. Although the technology used in most of these pads is very similar, you really should know which of the following pad types you are using. This will allow you to choose an exact or similar pad type in the trigger settings of the drum module. Doing this will give you settings that are a good starting point, thereby making it easier to get optimal trigger performance. Failing to set the pad type setting can make it nearly impossible to get good trigger performance.

Membrane-Switching Rubber Pads
Membrane-Switching pads have been around for decades, and are by far the most common type of pad. Most rubber and silicone dual-trigger pads are of this type. They use just one piezo to trigger both the head and the rim. The secret to getting the one sensor to trigger two zones is the use of a material called FSR – force-sensing resistors. FSR detects pressure, not vibration like a piezo, and is used on the rim of the pad. Fig. 4 shows an exploded view of a membrane-switching pad. The single piezo is mounted to the rigid plate on the underside of the pad’s rubber playing surface. My right hand is holding the FSR between the thumb and forefinger. As you can see, the FSR is a thin, flexible piece of plastic. A membrane-switching pad, like the one shown, can function in three different ways:

1) When you hit the center of the pad, it acts just like any other single-trigger piezo pad, and because of this, it can be used in any drum module.
2) To play the rim, you hit the rim and the center of the pad simultaneously. You see, the single piezo also functions as the sensor for the rim. There’s a circuit in the drum module that detects that the rim membrane is pressed (by the rimshot), and the module then sends the out sound assigned to the rim. To use the rim trigger on this type of pad, a drum module has to be designed to have this circuit – most do.
3) FSR also makes it possible to choke cymbals. Because the FSR in the rim senses pressure, the drum module can detect if the FSR has been pinched, and send out the data information needed choke off any sound playing that was triggered by that particular pad.

Membrane-switching technology is also used in three-way trigger pads like the ride cymbals pads from Roland and Yamaha, as well as some of Yamaha’s snare pads.

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