Sketches of Buchlidia

Sketches of Buchlidia is a piece made up of a series of sound fields performed in succession on the Buchla synthesizer. The general elements of each section were preconceived and rehearsed, but the piece’s performance is primarily the product of improvisation. Buchlidia is an adaptation of the word Buchlidian, used here in reference to an alien and imaginary world.

 

Notes on the Patch

Here I will describe the methods used to synthesize each of the sections in the piece. A picture of the patch is provided for reference.

  1. The first section begins with a low  A triangle wave on the 259’s Modulation oscillator which is triggered by the third pulse output from the 216 keyboard. By turning the second pot on the 257 Voltage Processor which is connected to the second Fluctuating Random Voltage output from the 266 the oscillator begins to randomly change frequency. This audio signal is the then sent to the 291e where the filter frequency and bandwidth are modulated using the same random voltage. This sound is paired with a pseudo-noise synthesized on the 259e with both wave form selectors set to 6 and CV from row B of the tunable portion of the 216 keyboard changing the frequency. The audio signal of 259e modulation oscillator whose frequency is being modulated using row A of the tunable keyboard is sent to the fm input on the principal oscillator. In addition, CV from the modulation oscillator is sent to three places. First it is sent to the 256 Voltage Adder and then used to modulate the attack time of the fourth envelope generator on the 281. Next it is sent to the second row on the 256 to change the spatial position of the 259e principal oscillators sound. Finally, it is sent to the pulse input for the fluctuating random voltage which is being used to modulate the frequency of the 259’s modulation oscillator as well as its filter settings on the 291e.
  2. The second section is announced by a droning A on the 259 principal oscillator  which is heavily frequency modulated by the 259 modulation oscillator. This is triggered by flipping the trigger switch all the way up on the 281’s second envelope generator.  The sound is made “stable” on A by removing the flow of random voltage used in the first section at the 257. The envelope of the 259 drone is also used as CV to attenuate the timbre modulation of the oscillator.  The 259e principal oscillator’s wave form selectors are then both switched to setting 2 so that the oscillator’s sound now delivers a definite pitch. The same tuning as before is used from row B of the 216 tunable keyboard, but now the pitches are far more obvious. The scale used is as follows in ascending order: A, D, Eb, E, A, Bb, C, E.
  3. The third section is dominated by the 250 Arbitrary Function Generator. The sequence is set to be a continuous seven stage loop. The 259 principal oscillator, now no longer using fm from the audio signal of the modulation oscillator, is now changing frequency according to CV output one from the sequencer. Pulses at each stage are sent to trigger output from the first envelope generator on the 281 producing the rhythm of the sequence. This means that the 259’s principal oscillator is now double gated as the second envelope generator is still set to continuously cycle. The effect is that the 250’s pulses create a continuous pulse which crescendo’s and decrescendo’s. The audio signal of the 259 is then sent to the first input on the 230 envelope follower (set to transient response) which triggers a noise source from the 266. This noise source is filtered at the 291 and it’s filter frequency and bandwidth are modulated using the first Fluctuating Random Voltage output on the  266 creating an interesting percussive effect. Eventually the 259’s modulation oscillator is switched to low mode and frequency modulation on the principal oscillator is reintroduced. After this, audio from the 259’s modulation oscillator as well as from 259e are triggered freely to fill some of the gaps between cycles of the sequence.
  4. The fourth and final section begins with the 259 principal oscillator changing pitch as the result of CV from the 250 sequencer but the sequence is now slowed down by turning the attenuator (receiving CV from the envelope follower) and the voltage offset on the 257 Voltage Processor all the way down. However, the flow of random voltage is reintroduced by turing the second pot on the 257 to the left so that not only is the principal oscillator changing pitch in time with the sequencer, but also being wildly frequency modulated by the audio signal of the 259’s modulation oscillator (still set to low mode) which is itself being frequency modulated by a fluctuating random voltage. Gradually the flow of random voltage is removed and the 259’s principal oscillator begins to once again drone on a very unstable A, going in and out of tune slowly and never really settling. The sensitivity of the envelope follower, which was turned to zero at the for the start of this section so that no noise is allowed to pass through it’s gate at the 292C, is turned up and the pulse response is set to sustained. This section is essentially a inversion of the first in terms of form as it begins with a randomly modulated voltage and ends with a drone.

 

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