| 摘要 |
An AC keying transient is simulated in a DC keyed electronic musical instrument by gating a pseudorandom frequency noise source output to the audio output circuit of the instrument during a brief time interval initiated by a legato pulse. The level of the noise is randomly selected from a range of values of a triangular wave form. The amplitude range of the triangular wave form is determined for each keyboard manual by chopping the highest drawbar voltage setting with an approximately 20 percent to 80 percent duty cycle higher frequency rectangular wave pulse gated by a low frequency square wave. The variable duty cycle wave form serves as an amplitude control for all keyboards with an equal effect being provided by the individual drawbar voltage settings for each keyboard. The chopper output is filtered to remove the variable duty cycle pulses leaving the triangular wave form which is integrated from the 6.8 hz square wave signal.
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