Don't Pull That Trigger!

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

Fig. 1

trigger

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.

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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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Fig. 4

True Dual-Trigger, Mesh Pads
True dual-trigger pads use two piezos, one to trigger the head and the other to trigger the rim. Most true dual-trigger pads have mesh heads. All piezo-based dual-trigger acoustic drum triggers are true dual-trigger devices. These would include pads and triggers from PinTech, Ddrum, and Roland. Beware, many drum modules do not accept true dual-trigger pads. There is still some proprietary technology in the e-drum world. Plugging this type of device into an input designed for membrane-switching pads will more than likely result in only the head portion of the pad or trigger working. Don’t be afraid; this mismatch won’t harm anything in the module. It truly is difficult to make smoke pour from a drum module!

FSR Pads
Although there have been a few FSR-based pads around for some time, the new Aquarian onHead pads, and inHead acoustic-electric drumheads are set to make FSR technology much more prevalent. Unless you are using a module that can supply the needed powered circuit to the FSR – there’s only one right now, the DITI trigger interface from Alternate Mode – you’ll have to use a special interface box between the FSR and the module. It’s available as a bundle with the inHead and onHead products.

Understanding Drum Modules: Types of Trigger Inputs

The types of trigger inputs available on drum modules can be broken down into four basic types: single trigger, membrane switching (dual and triple trigger), true dual trigger, and FSR. All of these inputs work slightly differently from one another.

1) Single-Trigger Inputs
The single-trigger input is self-explanatory. With single-trigger inputs, no matter what type of pad or type of cable you use, the pad will only function as a single-trigger pad. Only one sound at a time can be assigned to the pad. A mono cable is needed to connect to the module. A stereo cable with also work, but is not required.

2) Membrane-Switching Inputs
Membrane-switching is the most common type of input. This input type requires the use of a stereo cable to connect the pad to the module. If a mono cable (guitar cable) is mistakenly used, the pad will only trigger from the head. If your rim trigger isn’t working, check and see if you’ve made this mistake. I have never made this mistake ... no, not ever.

3) True Dual-Trigger Inputs
True dual-trigger inputs allow for the use of pads that are designed with two piezo elements, one for the head, and another for the rim. This input type also requires the use of a stereo cable.

4) FSR Inputs
Currently, dedicated FSR inputs are only found on the new Alternate Mode DITI (Drum Intelligent Digital Interface – Fig. 5) module. They allow for FSR-based pads and acoustic heads to be plugged directly into the module without using a special FSR interface box.

trigger

Fig. 5

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What You’ve Been Waiting For: Let’s Tweak Some Trigger Settings

Perhaps the best way to illustrate the functions of the different trigger settings is to take you through setting up an acoustic drum trigger. An acoustic trigger is much more difficult to get performing well than the common pad. If you can tweak a drum trigger into submission, any pad doesn’t stand a chance.

For this example I’m going to use an acoustic drum trigger on a tom. It is a single-zone trigger, so either a mono or stereo cable can be used to connect it to the module. I’ll be plugging it into a Roland TD-30 drum module, only because that’s what I have here in the studio. All the drum modules and trigger interfaces will have similar functions. Just to clarify, drum modules have built-in sounds; trigger interfaces do not.

Select the Trigger Type
After connecting the trigger, go into the trigger settings pages. Most modules “note chase,” so select the trigger input you want to edit by hitting the mounted tom. Then I select the trigger type, in this case RT10T. Setting the trigger type sets the trigger settings to values that work well with that acoustic trigger or pad type. (Fig. 6, Roland TD-30)

trigger

Fig. 6

Trigger types in a module will generally reference that manufacturer’s pads, not those of other manufacturer’s. When using pads with another manufacturer’s module, you’ll need to choose a trigger type that is similar in function. This is when it pays to know the subtleties of the different pad types. Starting off selecting an incompatible trigger or pad type can make it nearly impossible to get great triggering performance.

Set The Sensitivity
Next, set the sensitivity or gain of the trigger input. On the menu where input sensitivity is set, there is a graph (or text values) that shows the input level; it will change as you hit the drum softer and louder. To set the sensitivity, hit the drum as hard as you think you might in an actual performance. This is generally louder than you will hit it in a quiet room by yourself. Adjust the gain up or down so that the input sensitivity is peaking out just as the drum is hit the loudest. Then lower the sensitivity setting by one value to give a little cushion, in case the drum is hit even harder. (Fig. 7, Pearl Redbox)

Setting the sensitivity either too low or too high will limit the dynamic range of the input. If the level is too low, it’ll be difficult to get loud dynamics. If it’s too high, soft dynamics will be almost impossible. The sensitivity setting is extremely important. Take the time to get it right.

trigger

Fig. 7

Set The Threshold
Remember, threshold is the point at which a trigger signal is recognized by an input. The threshold is the first line of defense against false triggering. Begin by setting the threshold setting to “0,” its most sensitive, and then play the drum at the softest volume you’ll be playing. Slowly raise the threshold until the triggered sound begins to occasionally drop out. Then lower the threshold a value or two. Take note, the tendency will be to play the drum softer than you will in actual performance. Don’t be afraid of a few dropouts. Setting the threshold too low can cause unwanted double triggering and sympathetic triggering.

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Fig. 8, Alternate Mode DITI

Set The Mask Time
Mask time is an important setting. The mask time setting is mostly responsible for getting rid of double and false triggers. If possible, find out how your interface’s numeric values correspond to actual milliseconds, this will make setting this parameter a bit clearer. If not, you’ll just have to rely on your ear.

trigger

Fig. 9, Alternate Mode DITI

Take the mask time setting all the way down to “0,” then play the drum as fast as you will in actual performance. Raise the mask time setting until the double triggering is gone, or nearly gone. Next, continue to increase the value until some played notes don’t trigger. At this point, lower the setting a few notches.

For reference, the space between notes in a buzz roll is around 15ms. The space between flams is about 40—50ms. Generally, the snare will have the shortest mask time, the toms will have mask times that increase as the toms get bigger and lower in pitch. The kick drum can have a mask time of 50ms or more.

Headroom
I use the headroom setting as a way to fine tune the mask time setting. For instance, if the drum is triggering fairly well, but occasionally there is a false or double trigger, I’ll gradually raise the headroom setting until it goes away.

Using Crosstalk
Crosstalk is the last setting to visit, and rather easy to tweak. If another input triggers when you strike a pad, gradually raise the crosstalk level on the offending input until the amount of crosstalk is either acceptable or gone. You may have to adjust this setting on more than one pad to get rid of all the crosstalk happening.

It’s possible that after following the method above, there still may be either note dropouts or double triggering. All I can say is make minor changes to the mask time, threshold, and sensitivity. It’s a balancing act. There are no fixed rules; you must experiment and tweak. You may even find that choosing another trigger type may magically work perfectly. (Fig. 10, Yamaha DTX900)

trigger

Fig. 10

Go Forth And Trigger!

Experimentation is the key to understanding trigger input settings. Remember, you can’t break anything by experimenting!

Mike Snyder loves drums, technology, and Lucy, his golden retriever. Contact him on Twitter: @drumbz or by email at .(JavaScript must be enabled to view this email address).