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EG01 - EG with EMS-syle Repeat
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Introduction
The EG produces a CV that varies over a period of time. It’s start is triggered by a Gate or Trigger signal.
The main use for an EG is to vary the volume of a sound, (when used to control a VCA), to reproduce the way natural instruments sound. E.g. a piano sound starting loud when the key is struck, then gradually dieing away. It can also be used to change the timbre of a sound over time, by controlling the cut-off frequency of a VCF.
The most common EGs are ADSR, AD and AR (Attack, Decay, Sustain, Release). The attack time adjusts the rate at which the envelope will rise to its peak value. This is initiated with a Gate signal. The Decay adjusts the rate the signal takes to fall to the Sustain level. The Sustain level adjusts the level that the EG signal will sustain from the end of the Decay time till the end of the Gate signal (i.e. when the key is release). The Release time adjusts the rate the signal takes to fall from its current level to zero, after the end of the Gate signal (when the key was released). If a short Trigger signal is used to initiate the EG, there will be no Decay or Sustain portion to the EG signal. The signal will rise to peak level (Attack), then imidiately fall from peak to zero at the Release rate.
Use
Sockets
Trigger In A positive gate or trigger voltage in here will activate the ADSR sequencer.
+ EG Out A full level positive envelope signal from this socket. Level pot has no effect.
+/- EG Out The EG signal is positive. By pulling out the EG knob, the signal is inverted (negative).
Controls
Attack After receiving a Gate signal, this sets the time is takes the envelope to reach full level.
Decay After reaching full level, this sets the time it takes the envelope to decrease to the Sustain
level.
Sustain The sets the Sustain level. The envelope signal will remain at the Sustain level (after
decreasing from the maximum level) as long as there is a Gate signal present at the
Trigger in socket (i.e. as long as a key is held down).
Release After the key is released (the Gate signal no longer present), this sets the time it takes for
the envelope signal to decrease to zero.
Special EMS-Style Repeat Function
The EG01 has an EMS-style repeat function which is easy to use and adds powerful modulation capabilities.
When the sustain level is set to zero the repeat function will be active. The envelope will repeat (re-trigger itself) so as soon as the envelope finishes its cycle, it starts all over gain. In this mode the EG becomes an LFO or Oscillator. The speed is set by the Attack and Decay time. (The Release control will have no effect). By setting very short times an audio signal will be present!
Whether the repeat is short giving high frequencies (audio signals) or slow (like an LFO), by varying the Attack or Decay times you are changing the wave shape of the output. Anything from Saw to Triangle to Reverse Saw wave froms can be created.
The unique way in which the EG01 repeat works is that it will only repeat as long as the Gate voltage is at the Trigger input (i.e. the key is held down/sustained). This is a great bonus compared to other repeating envelopes in that rather than repeating indefinately, it will only repeat as long as you want it to (by controlling the length of the Gate signal). One application of this is by setting the repeat function to create an audio signal. The output will only produce audio when a Gate signal is present. This gives you a gated audio signal - effectively an Oscillator through a VCA.
Concussor
Modular Synthesizer from Analogue Solutions
Tel:+44 1384 35 36 94 Fax:+44 1384 35 36 94
e&oe (c) 11 2002
