The bass drum requires the largest speaker (preferably a subwoofer), because subwoofers are designed push a large amount of air in order to produce lower frequencies. Woofers and midrange drivers are intended to reproduce midrange frequencies, and they tend to be more sensitive and move less dramatically. These speakers are fit for Snare drums and smaller tom toms. My personal experimentation and research has also shown that speakers designed in the 1970s and 1980s are generally less sensitive and therefore move more than their modern counterparts.56 The speakers are driven by pulse width modulation (PWM), a type of modulation technique. PWM is also used in telecommunication as a method of transmitting time code. PWM is a square wave characteristically, and in the use of the Shred device it allows the speaker to become active or inactive in order to strike the drum skins.
The device is constructed from malfunctioning speakers that once functioned in Hi-Fi systems. The speakers are taken and cut down so only that only the driver and the spider remain. This deprives the speaker of any sonic quality, but it retains the ability to produce a driving force strong enough to propel a mallet into a drum skin. The characteristics of the speaker also allow them to be programmed to hit the drums in various intensities, producing an output ranging from 70dB to 120dB. Typically, the speaker size is directly proportionate to the size of the drum that the device is intended to function in.