ARP2600 - Fundamentals of Music Technology - Cyborgstudio.com

SECTION15THE ARP SEQUENCERAN INTRODUCTIONAn in-depth look at the ARP sequencer would easily fill 40 pages, and is beyond the scope of this book.This section is intended to provide only a brief introduction to this rare instrument. Unfortunately,many of its wonderful features can not be explored at this time, but for the curious, there is a good dealof information about this instrument on the web.When ARP produced its first modular synthesizer, the mammoth 2500, one of the modules which couldbe included was a sequencer. A sequencer is a device which puts out a series of control voltages whichthe user is able to preset. The sequencer then repeatedly steps through these voltages. ARP later madea revised version of the sequencer module available as a separate unit. (See Figure 15-1)Figure 15-1: The ARP sequencerMost analog sequencers allow users to program sequences of 1 to 16 steps. A step is an event in asequence, which is usually characterized by the sequencer putting out a voltage. Sequencers put out upto sixteen steps, because there are sixteen sixteenth notes in a measure of common time, which is themost common musical meter. The voltage that the sequencer will output when it reaches any given stepis set using a knob or a slider. (This varies from sequencer to sequencer.) The ARP sequencer usessliders with blue and white slider caps, and there is one slider for each potential step. (See Figure 15-1)The ARP sequencer is highly sought after as analog sequencers go since it offers two voltage quantizers.A voltage quantizer is a module which will raise or lower control voltages slightly so that thevoltage will always fall on a tone from a chromatic scale. When the INITIAL FREQUENCY slider onan oscillator is moved, the frequency of the oscillator changes in a continuous smear. However, if thefrequency of an oscillator is being modulated by the sequencer, and the slider on a particular step of thesequencer is moved up or down, the pitch of the VCO will change up or down in a chromatic scale. CDtrack 84 Imagine how difficult it is to set particular notes on a sequencer when one must go through atuning process for each note. The ARP sequencer’s voltage quantizers eliminate this problem.119