gbuzz — Output is a set of harmonically related cosine partials.

*ifn* -- table number of a stored function containing a cosine wave. A large table of at least 8192 points is recommended.

*iphs* (optional, default=0) -- initial phase of the fundamental frequency, expressed as a fraction of a cycle (0 to 1). A negative value will cause phase initialization to be skipped. The default value is zero

The buzz units generate an additive set of harmonically related cosine partials of fundamental frequency *xcps*, and whose amplitudes are scaled so their summation peak equals *xamp*. The selection and strength of partials is determined by the following control parameters:

*knh* -- total number of harmonics requested. If *knh* is negative, the absolute value is used. If *knh* is zero, a value of 1 is used.

*klh* -- lowest harmonic present. Can be positive, zero or negative. In *gbuzz* the set of partials can begin at any partial number and proceeds upwards; if *klh* is negative, all partials below zero will reflect as positive partials without phase change (since cosine is an even function), and will add constructively to any positive partials in the set.

*kmul* -- specifies the multiplier in the series of amplitude coefficients. This is a power series: if the *klh*th partial has a strength coefficient of A, the (*klh* + n)th partial will have a coefficient of A * (*kmul* ** n), i.e. strength values trace an exponential curve. *kmul* may be positive, zero or negative, and is not restricted to integers.

*buzz* and *gbuzz *are useful as complex sound sources in subtractive synthesis. *buzz* is a special case of the more general *gbuzz* in which *klh* = *kmul* = 1; it thus produces a set of *knh* equal-strength harmonic partials, beginning with the fundamental. (This is a band-limited pulse train; if the partials extend to the Nyquist, i.e. *knh* = int (sr / 2 / fundamental freq.), the result is a real pulse train of amplitude *xamp*.)

Although both *knh* and *klh* may be varied during performance, their internal values are necessarily integer and may cause “pops” due to discontinuities in the output. *kmul,* however, can be varied during performance to good effect. *gbuzz* can be amplitude- and/or frequency-modulated by either control or audio signals.

N.B. This unit has its analog in *GEN11*, in which the same set of cosines can be stored in a function table for sampling by an oscillator. Although computationally more efficient, the stored pulse train has a fixed spectral content, not a time-varying one as above.

Here is an example of the gbuzz opcode. It uses the file *gbuzz.csd*.

**Example 412. Example of the gbuzz opcode.**

See the sections *Real-time Audio* and *Command Line Flags* for more information on using command line flags.

<CsoundSynthesizer> <CsOptions> ; Select audio/midi flags here according to platform -odac ;;;realtime audio out ;-iadc ;;;uncomment -iadc if realtime audio input is needed too ; For Non-realtime ouput leave only the line below: ; -o gbuzz.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> sr = 44100 ksmps = 32 nchnls = 2 0dbfs =1 instr 1 kcps = 220 knh = p4 ;total no. of harmonics klh = p5 ;lowest harmonic kmul line 0, p3, 1 ;increase amplitude of ;higer partials asig gbuzz .6, kcps, knh, klh, kmul, 1 outs asig, asig endin </CsInstruments> <CsScore> ; a cosine wave f 1 0 16384 11 1 i 1 0 3 3 1 ;3 harmonics, lowest harmonic=1 i 1 + 3 30 1 ;30 harmonics, lowest harmonic=1 i 1 + 3 3 2 ;3 harmonics, lowest harmonic=3 i 1 + 3 30 2 ;30 harmonics, lowest harmonic=3 e </CsScore> </CsoundSynthesizer>