musical tones. In the 1990s and 21st century, some churches began using electronic-trigger equipped pedalboards for the 16′ and 32′ stops. The MIDI information from the electronic pedalboard sensors triggers pipe organ sounds from digital sound modules (e.g., Wicks CM-100, Ahlborn Archive Modules, or Walker Technical sound generation), which are then amplified through loudspeakers. These MIDI systems can be much less expensive than metal or wooden bass pipes, which are very costly to purchase and install, due to their heavy weight (up to one ton per pipe), large size, and need for large amounts of wind. Another rationale for using MIDI systems is that it may be easier to get a focused sound with a MIDI system, because all of the bass tone emanates from a single speaker or set of speakers. With traditional pipes, it can be difficult to give the pedal division a focused sound, because the large pipes tend to be spread out over the entire organ pipe chest. This cost-saving measure has been the subject of controversy in the organ scene. Advocates of MIDI pedal divisions argue that a good quality MIDI system produces a better tone than an inexpensive set of bass pipes with money-saving "shortcuts" such as using stopped pipes and resultant tones to reduce the number of required pipes. However, critics dislike the way that the use of MIDI pedal divisions blends electronically amplified lower voices with the natural, wind-driven upper ranks. Willi Apel and Peter Williams argue that by definition, an organ must make its sound by air flowing through pipes. Some critics argue that the bass tone from a MIDI pedal division, which comes from an amplified 12-inch subwoofer, is not as "natural" and "open-sounding" as the vibrations from a massive, wind-driven 32-foot pipe. Design Keyboards Pedalboards range in size from 13 notes on small spinet organs designed for in-home use (an octave, conventionally C2–C3) to 42 notes (three and a half octaves, G1–C5) on church or concert organs. Modern pipe organs typically have 30- or 32-note pedalboards, while some electronic organs and many older pipe organs have 25-note pedalboards. Besides the number of pedals, the two main identifying aspects of a pedalboard are: whether all the pedals are at the same height relative to the floor ("flat"), or whether the pedals in the middle are lower than those on the outer edges, forming a curved-in shape ("concave"), and whether all