OMChroma User ManualPredefined Classes > Karplus-Strong > Karplus-Strong Synthesys with PLUCK-2

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Karplus-Strong Synthesys with PLUCK-2

Tutorial PLUCK-2 Methods

Specific Slots

Name	Description	Default value
amp	Maximum Amplitude. Linear from >0.0 to 1000 or in dB from 0 to -∞ (see Tutorial Getting Started 02 - Amplitude and Internal Editor for more details)	-6.0
freq	(Minimum) fundamental frequency [Hz]	440.0
buf	Intended pitch value in Hz, used to set up a buffer of 1 cycle of audio samples which will be smoothed over time by a chosen decay method. The buffer normally anticipates the value of the frequency, but may be set artificially high or low to influence the size of the sample buffer.	220.0
dec	Decay time % of the total duration of the amplitude envelope [H%]	0.8
ranfun	Function number of the random source [GEN]	0
meth	Method of natural decay. There are six, some of which use parameters values that follow simple averaging. A simple smoothing process, uninfluenced by parameter values. stretched averaging. As above, with smoothing time stretched by a factor of iparm1 (>=1). simple drum. The range from pitch to noise is controlled by a 'roughness factor' in iparm1 (0 to 1). Zero gives the plucked string effect, while 1 reverses the polarity of every sample (octave down, odd harmonics). The setting .5 gives an optimum snare drum. stretched drum. Combines both roughness and stretch factors. iparm1 is roughness (0 to 1), and iparm2 the stretch factor (>=1). weighted averaging. As method 1, with iparm1 weighting the current sample (the status quo) and iparm2 weighting the previous adjacent one. iparm1 + iparm2 must be <= 1. 1st order recursive filter, with coefs .5. Unaffected by parameter values.	4
ipar1	Parameter required by some values of meth	0.5
ipar2	Parameter required by some values of meth	10.0

Class description

The PLUCK-2 Class realizes a Karplus-Strong Synthesys (naturally decaying plucked string or drum sound) with the following controls:

The main amplitude,
The fundamental frequency,
The buffer size,
The stored function (GEN routine) used to initialize the cyclic decay buffer. If ifn = 0, a random sequence will be used instead.
The decay time of the total duration of the amplitude envelope.
The Method of natural decay (see specific slots' description).

Patch description

These examples collect all methods each of which has its own feature (see specific slots' description). Watch out to the optional parameters and their range and relationship.

Common Red Patches

For the red patch C#ed and Synt see Appendix A

Tutorial PLUCK-2 Buffer and runfun

Patch description

The example F fixes on the buffer size values. With increasing values the sound changes into more muffled and less brilliant.

The example G gives 5 GEN subroutines as stored function used to initialize the cyclic decay buffer. The default one (f0) is random sequence, the kind of function (given as f- functions to the keyword inlets "tables" of synthesize) influence the timbre of the sound.

Common Red Patches

For the red patch C#ed and Synt see Appendix A