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EKS Tuning and Decay Exercises

Use the shell script in §3.9 below to generate a pd synthesizer based on the EKS, and drive it either from the Virtual Keyboard or from an external MIDI keyboard, as described in the Faust intro.

  1. Checking Tuning
    1. Using delay (no interpolation) for the main delay line, determine if you can hear the tuning error when the sampling rate is 44.1 kHz, and if so, report the lowest MIDI key-number and other settings used.
    2. Repeat using fdelay (linear interpolation).
    3. Repeat using fdelay4 (4th-order Lagrange interpolation).

  2. Uniformity of Decay
    1. Using fdelay for tuning, set the brightness set to 1 and the decaytime to maximum. Determine the set of MIDI key numbers, if any, at which there is noticeably reduced decay. These are notes that sound markedly brighter than their neighbors and tend to ``jump out'' when playing a chromatic scale.

    2. Repeat with brightness set to 0.

    3. Repeat with brightness set to 1 and using fdelay4 in place of fdelay.

  3. Measure and report the decay time (either by ear, or by measuring $t_{60}$ on a dB-magnitude waveform display) at notes C1, C2, C3, and C4 when the decay-time parameter is set to its minimum and maximum values. How good is $t_{60}$ is a definition of decay time?

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Download faust_strings.pdf

``Making Virtual Electric Guitars and Associated Effects Using Faust'', by Julius O. Smith III,
REALSIMPLE Project — work supported in part by the Wallenberg Global Learning Network .
Released 2013-08-22 under the Creative Commons License (Attribution 2.5), by Julius O. Smith III
Center for Computer Research in Music and Acoustics (CCRMA),   Stanford University