ARP2600 - Fundamentals of Music Technology - Cyborgstudio.com

SECTION SEVEN: ADSR AND AR GENERATORS - 057HOLD IT RIGHT THERE!The next stage of the envelope is unique in that it is the first, and only stage to deal with a level insteadof time. The third stage of an envelope is called sustain and it determines the amount of control voltagethe EG will put out while a key is being held down. Of course, this creates another little conundrum.How does the EG know when a key is being held down?Yet another pin on the cable which connects the keyboardto the cabinet is used to send voltage to the cabinetas long as a key is being held down. This voltage,which is ‘on’ while a key is held down, is called aTimesustain level gate signal. There is an input for an external gate signalwhich is located just to the left of the trigger input.Figure 7-6: SustainOnce again, specific uses will be described later. Aswith the trigger pulse, the manual start button will also produce a gate signal as long as it is held down,so that all the stages of the envelope can be heard.VoltageBecause sustain refers to a level and not a time period, the sustain stage sometimes causes some confusion.The time between the end of the decay and the beginning of the final stage is called the sustain,but the level of this stage is also referred to as sustain. The amount of time this stage lasts is determinedby the length of time a key on the keyboard is held down or the length of time the manual start buttonis held down.PLEASE RELEASE ME; LET ME GOFinally, when a key on the keyboard is released, the gate signal being fed to the EG is abruptly cut off,and the EG goes into its final stage, called release. Release determines the time it takes the envelopegenerator to go from the sustain level to no voltage. Release can be seen in Figure 7-7 where the releaseportion of the envelope is drawn in red.Taking the first letter of each stage, one gets the abbreviation“ADSR” which is pronounced “Add-Sir.”One will frequently refer to the ADSR generator, butthe other generator on the ARP is merely called theA-R generator. Although Bob Moog invented the VCOand VCF, the idea for the ADSR generator was notTimehis. Although the Moog music company built the firstADSR generators, the module was the idea of Russianelectronic music composer Vladimir Ussachevsky (1911-1990), who was Wendy Carlos’s teacherFigure 7-7: Relaseat the Columbia-Princeton Electronic Music Center. How are each of these times and levels set? TheARP 2600 provides the user with a separate slider for each stage of the envelope. With the sliders, onecan almost see a sort of graphic representation of the envelope about to be produced.Voltage