User Manual
Buchla 259e Twisted Waveform Generator
Intro
Overview
Buchla Philosophy
Detailed Description
Indicators
Inputs
Outputs
The Buchla 259e Module In Use
Credits
Donald Buchla, an inventor based in Berkeley, USA, started building and designing electronic instruments in the early 1960s. It all started when he was commissioned by avant-garde composer Morton Subotnick to build a modular instrument for composing and performing live electronic music. The result was called the Buchla Box—Don Buchla’s first modular synthesizer. This evolved into Don’s first commercially available system, the Buchla 100 system, which was followed in the 70s by the legendary Buchla 200 system.
In the early 2000s, Don decided to reinvent and reimagine the 200-system, and the new Buchla 200e system was born. The 200e system is an interesting hybrid between analog and digital technology, and the Buchla 259e module is a perfect example.
The 259e is in one sense a modern day digital implementation of the original Buchla 259 Complex Wave Oscillator, but in many other ways it’s a different beast altogether. The 259e's crazy memory scanning functionality and its cold and very digital sounding waveshaping capabilities, with plenty of characteristic aliasing distortion, makes it a prime candidate for sonic experimentation beyond the ordinary.
Softube’s Buchla 259e Twisted Waveform Generator plug-in for Modular features the digital waveshaping, aliasing noise and fold over frequencies of the original hardware. The plug-in captures all the self-modifying, screeching, snarling responses from the original’s downright odd inner workings—which added “twisted” to its name.
The 259e consists of two separate oscillators. One is the Modulation oscillator, which primarily serves to modulate the second one, called the Principal oscillator. The Modulation oscillator can be switched between High and Low frequency ranges, where High generates notes in the audible region and Low is mostly for when the oscillator is used as an LFO which modulates the Principal oscillator. The Modulation oscillator can be switched between three classic waveform shapes, and three different modulation targets can be selected, one by one or in any combination.
The sine wave generated by the Principal oscillator is simultaneously applied to two of the eight available waveshape tables. Step through the tables (1-5, a-c) by pushing the green and red buttons. Green and red LEDs indicate which tables are currently selected.
Tables a, b and c are actually not tables in the classical sense—they are simply portions of the 259e operating program, full of unpredictable noise and frequent silences. When these tables are selected, the FM controls are re-assigned to table scanning functions and the FM inputs become table modulators. In this state, the Mem Skew LEDs above the FM controls light up.
A morph voltage pans between the two tables and a warp voltage varies the amplitude of the sinusoidal (driving) waveform. Both these functions can be modulated by the modulation oscillator.
The Buchla systems vary the harmonic content in their patches by using a waveshaper on a rudimentary sound source such as a sine oscillator, rather than shaping of harmonic content through filtering, which is the more commonly used method. Buchla’s type of synthesis is often referred to as the West Coast style.
Where a VCF removes harmonic content from a signal, a waveshaper warps the waveform by applying either a fixed or variable mathematical function. This real time process alters the shape of the waveform, adding harmonics and resulting in a more abrasive sound compared to the typical East Coast style characteristics (classic subtractive synthesis).
In a Buchla synthesizer system, audio and modulation signal paths are separated by their different jack and cable formats. Audio jacks are silver and AC coupled, while modulation jacks are colored “banana” jacks which are DC coupled. The form factor of the jacks and the different cables make it easy to see which signal goes where and creates a natural signal flow in the Buchla environment.
Softube has reimagined the 259e in a Eurorack environment, adapting levels and connectivity to work as any Eurorack module. This means that the 259e module featured in Modular, unlike its hardware counterpart, will have no limitations when it comes to connectivity— you can connect any type of output to any kind of input, whether it’s audio or modulation. But for the sake of familiarity, we kept the look and color of the hardware audio and modulation jacks. Softube has also adapted the signal levels to harmonize better with the other modules in the Modular system.
The following adaptations have been made when converting the Buchla 259e to Softube Modular:
- Audio and CV can be freely patched to each other.
- CV voltages rescaled by around 0.9 times, so that setting the frequency CV attenuators to max gives a 1V/oct response.
- Audio voltages have been rescaled by around four times, to match Eurorack levels better.
- Remote Enable replaced by MIDI Enable. Press once to go to MIDI learn mode (blink), play a MIDI note and it locks to that channel. Press again to turn MIDI off.
- the AC coupling of the FM jacks was disabled when in Slew mode in order to make them more useful when in use with regular DC CV modulation such as LFOs, envelopes and sequencers.
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- Main outputs
- Midi enable
- Principal oscillator, Timbre section
- Principal Oscillator
- Modulation oscillator, Sync behaviour
- Modulation conversion between Modulation oscillator and Principal oscillator
- Modulation oscillator
MIDI Enable Button
When clicked once in its preset state, the LED will start flashing, an indication for that the 259e is awaiting a MIDI note on message. When the MIDI note is received, the 259e automatically sense will sense on which MIDI channel and lock onto that channel (LED is lit). By clicking once more, MIDI is reset to off status and LED will go unlit. Received MIDI range is from A-1 to A7 (8 octaves), same range as coarse tune. MIDI pitchbend is received on the same MIDI channel and responds to +-1 octave.
MIDI Prin Sync Button (Modulation Osc Sync)
This button toggles between the different reset behaviors of the Modulation Oscillator:
- Preset mode - no synchronization is set (all LEDs are unlit).
- Soft sync mode - uses a phase-lock loop to achieve synchronization.
- Hard sync mode - truncate synchronization to the Principal oscillator. This means that the Principal oscillator will hard reset the Modulation oscillator.
- MIDI note sync - synchronisation by incoming MIDI note messages on the channel set by the MIDI enable function (see description above). This means that this function will not be operational when MIDI enable is set to off.
Morph
The Morph knob is the offset used to fade between the green and red wave-shape tables of the Principal oscillator. When this knob is fully counter-clockwise and no modulation is applied to morph from neither the Modulation oscillator or the Principal Osc Morph CV jack, the green LED just beneath the knob will be lit indicating that presently, only the green wave-shape is output on the Principal outputs. When turning the morph knob gradually clockwise, more and more of the red wave-shape will be faded into the Principal outputs, and at fully clockwise, only red is output. The Morph knob works as an offset, to which modulation is added, either via the Principal Osc Morph CV input or via the Modulation Index routing.
Principal Osc Morph CV
This is the bi-polar amount knob to scale the incoming CV at the Principal Osc Morph CV jack. At 12 o'clock position, amount is 0 and then increasing clockwise up to 1 times scaling at the 5 o'clock position. Turning the knob counter-clockwise from 12 o'clock to 7 o'clock position sets amount to fully -1 times (CV has inverted impact on morph). Modulating morph CV is always relative to the position of the Morph knob which works as an offset.
Modulation Index CV
This is the bi-polar amount knob to scale the incoming CV at the Modulation Index CV jack. At 12 o'clock position, amount is 0 and then increasing clockwise up to 1 times scaling at the 5 o'clock position. Turning the knob counter-clockwise from 12 o'clock to 7 o'clock position sets amount to fully -1 times (CV has inverted impact on the Modulation Index). Modulation CV is always relative to the position of the Modulation Index knob (offset). See further description on Modulation Index below. The signal patched into the Modulation Index CV input will affect the amount of modulation selected via Mod Type and offset via the Modulation Index, positively or negatively. For example FM amount between Modulation oscillator and Principal Oscillator can thus be affected by an external ADSR envelope.
Modulation Index
The Modulation Index knob sets the amount of the selected modulation between the Modulation oscillator and the Principal oscillator. This is done via Mod Type button (see description below). The Modulation Index knob works as an amount offset, which is affected by the signal at Modulation Index CV input. This signal can be set to affect the Modulation Index positively or negatively.
Timbre Bank Buttons
These green and red buttons control the different wave-shape tables of the Principal oscillator. There are different wave-shape tables for the green and red sides, although some of them are the same. When clicking ov n one of the green and red buttons, the corresponding colored LED will move one step up the wave-shape selector ladder. Both sides, green and red, will share the same indicator which makes the LED lit up orange when green and red indication appears on the same step. When clicked through until step C, one more click will cause the that side to cycle back to step 1. Green and red Timbre banks are the same for position 1, A, B and C, but differ slightly in harmonics for position 2,3,4 and 5 on the green and red side. Positions 1 through 5 are different regular wave-shapes, while position A-C reflect the fun and quirky memory bank mode. In this mode, the wave-shapes are based on scanning through the digital code memory of the Buchla 259e with the Mem Skew function (see further description below).
- Modulation Index Offset and Attenuator
- Green and red Timbre selection
- Midi enable button
- Morph knobs
- Warp knobs
- Modulation oscillator coarse and Fine tune
- Green and red FM Amount (or Mem Skew)
- Pricipal Coarse and Fine tune
Principal Osc Warp
The Osc Warp knob controls the folding of each of the timbres (except timbre nr 1, sine) working as an offset for the modulation applied to the Principal Oscillator Warp CV input. Increased warp changes the output harmonics of the Principal Oscillator. When the in Mem Skew mode, the Principal Osc Warp knob will set the range of Memory being scanned via the Mem Skew Index and CV input.
Buchla 259e Principal Oscillator Timbres: Green Timbres
Waveforms captured at 440hz
Buchla 259e Principal Oscillator Timbres: Red Timbres
Waveforms captured at 440hz
Principal Osc Warp CV
This bi-polar amount knob to scales the incoming CV at the Principal Osc Warp CV jack. At 12 o'clock position, amount is 0 and then increasing clockwise up to 1 times scaling at the 5 o'clock position. Turning the knob counter-clockwise from 12 o'clock to 7 o'clock position sets amount to fully -1 times (CV will have inverted impact on the Principal Osc Warp). Principal Osc Warp CV is always relative to the position of the main Principal Osc Warp knob (offset). The signal patched into the Principal Osc Warp CV input will affect the Warp amount, positively or negatively.
Mod Type button
This button determines which destination, or combination of destinations, the Modulation Oscillator will modulate through the Modulation Index. Multiple presses on this button switches between the none (all three LEDs - morph, warp and ptch, are unlit), one, two or all three of the available Modulation destinations: Morph, Warp and Ptch (Pitch). There are in all 7 different combinations available.
Modulation Osc Fine
This knob is for fine-tuning the pitch of the Modulation Oscillator. The range is roughly up and down two semitones.
Principal Osc Fine
This knob is for fine-tuning the pitch of the Principal Oscillator. The range is roughly up and down one and a half semitone.
Modulation Osc Coarse
The Modulation Osc Coarse knob sets the coarse tuning for the Modulation oscillator. When Modulation Osc Range is set to Low the range of this knob goes from 0.25Hz to 64Hz. When set to High range is 27,5Hz to 7040Hz. In Pitch Track mode, the knob function as offset to pitch set by the Principal Oscillator frequency.
Principal Osc Coarse
The Principal Osc Coarse knob will set the coarse tuning of the Principal oscillator ranging from 27,5Hz up to 7040Hz. In MIDI mode this knob will not always reflect the pitch heard because, in MIDI mode, pitch is determined by the last MIDI note played. And when you then tweak the Coarse-knob, it will work as an offset from the MIDI note. In practise this means that if you play an A4 in MIDI mode, the following time you adjust the Principal Osc Coarse knob, the pitch of the Principal Oscillator will start at 440Hz regardless of where the knob points, and work in linear fashion towards the lo and hi extreme endpoints of the knob. A new MIDI note will force the frequency back to that note value. This means that if a MIDI sequence is played, the Principal Osc Coarse knob can be used to temporarily tweak the frequency of the active notes, while it will always jump back in tune for every received MIDI note.
Modulation Osc Range button
- Pitch track - when this LED is lit, the Modulation Oscillator pitch is tracking that of the Principal Oscillator, but offset by the Modulation Osc Coarse knob. In this mode, the LED above the Modulation Osc Coarse knob indicates if the pitch-relation to the Principal Oscillator is below (red light), above (green light), or spot on (LED is unlit) when the Modulation Osc Coarse knob is set to 12 o’clock.
- High - the Modulation Oscillator operates in the audio-region with the Coarse knob ranging from 27 to 7040 Hz. In this mode, the LED indicator above the Coarse knob remains unlit.
- Low - the Modulation Oscillator operates in the sub-audio range with the Coarse knob ranging from .25 Hz to 64 Hz. The LED indicator above the Coarse knob in this mode reflects the cycles of the Modulation Oscillator (red being negative part and green being positive part).
Modulation Osc FM
This knob sets the amount of frequency modulation to affect the Modulation Oscillator when patching in an external signal into the FM in input jack. When the Principal Oscillator’s green timbre table is in Mem Skew mode (using bank A,B or C), this knob’s functionality is re-assigned to table-scanning. This is indicated by the Mem Skew green LED indicator being lit above this knob. In Mem Skew mode, the Modulation Osc FM knob will act as an offset for the Principal Oscillator green table scanning while signals patched into the FM in input jack will affect the scanning (without any attenuation).
Modulation Osc CV
This knob will attenuate modulation signals patched into the CV in input jack situated below this knob. Knob position 12 to 5 o’clock will attenuate positively clockwise (0 to 1 v/octave), while knob position 12 to 7 o’clock will attenuate negatively anticlockwise (0 to -1v/ octave).
Principal Osc FM
This is the amount of frequency modulation to affect the Principal Oscillator when patching in an external signal into its’ FM in input jack. When the Principal Oscillator’s red timbre table is in Mem Skew mode (using bank A,B or C), this knob’s function is re-assigned to tablescanning. This is clearly indicated by the Mem Skew red LED indicator being lit above this knob. In Mem Skew mode, the Principal Osc FM knob will act as an offset for the Principal Oscillator red table scanning while signals patched into the Principal Oscillators FM in input jack also will affect the scanning (without any attenuation).
Principal Osc CV
This knob will attenuate modulation signals patched into the Principal Oscillator CV in input jack situated below. Knob position 12 to 5 o’clock will attenuate positively clockwise (0 to 1 v/octave), while knob position 12 to 7 o’clock will attenuate negatively anticlockwise (0 to -1v/octave).
MIDI enable LED
This LED starts blinking when clicking on the MIDI mode button, indicating that the 259e is waiting for a MIDI note on message to determine which MIDI channel to listen to. When having received a MIDI note, this LED will stop blinking and remain lit until MIDI mode button is clicked again to switch 259e to manual mode.
MIDI prin sync LED
This LED indicates sync status of the Modulation Oscillator. For further detailed information on the different indicated sync modes, see description above (MIDI prin sync button).
Timbre Bank LEDs
These LEDs tells you which timbre banks, green and red that are selected for the Principal Oscillator.
Morph LEDs
These LEDs indicate the balance of the timbre banks heard on the Principal Oscillator output, directly reflecting the sum of the Morph knob and Principal Osc Morph CV input.
Mod Type LEDs
These LEDs indicate which modulation destinations in the Principal Oscillator that currently are selected to be connected to the Modulation Oscillator. Selected destinations can be any combination of one, two or all three destinations. None is also an option (no LEDs lit).
Modulation Osc LED
Situated just above the Modulation Osc Coarse tune knob is the Modulation Osc LED reflecting the internal function of the oscillator. When the Modulation Oscillator is set to Low Mode it will reflect the oscillator rate with red being the negative portion and green being the positive portion of the waveform.
Mem Skew LED Green
This LED is lit when the Principal Oscillator green timbre bank is using one of the memory banks A, B or C. It indicates the temporarily changed functionality of the Modulation Osc FM knob and CV input (for further detailed information, see above description about the Modulation Osc FM knob).
Modulation Range LEDs
These LEDs reflect Modulation Oscillator operational mode: Low, High or Pitch Track. See further detailed description above on the Modulation Oscillator Range button.
Mem Skew LED Red
This LED is lit when the Principal Oscillator red timbre bank is using one of the memory banks A, B or C. It indicates the temporarily changed functionality of the Principal Osc FM knob and CV input (for further detailed information, see above description about the Principal Osc FM knob).
Principal Osc Morph CV input
This is the CV input for the blend of the red and green timbre banks on the Principal Oscillator.
Modulation Index CV input
CV input for scaling the Modulation Index between the Modulation Oscillator and Principal Oscillator.
Principal Osc Warp CV input
This jack is the input for externally controlling the Warp function of the Principal Oscillator from a CV modulator (LFO, envelope, etc).
Modulation Osc FM input
Audio input for frequency modulation of the Modulation Oscillator or, in Mem Skew mode, external CV control of the green timbre banks memory scanning. This jack is AC coupled in ordinary FM mode which means that it will work better with audio signals (this is how the original hardware works). In Mem Skew mode this jack will change to DC coupled mode to better work with modulation signals such as LFOs, envelopes and sequencers.
Modulation Osc CV input
This jack is external CV control of the Modulation Oscillator pitch, tracking 1V/octave when the Modulation Osc CV knob is set to max (preset value).
Principal Osc FM inpu
Audio input for frequency modulation of the Principal Oscillator or, in Mem Skew mode, external CV control of the red timbre bank’s memory scanning. This jack is AC coupled in ordinary FM mode which means that it will work better with audio signals (this is how the original hardware works). In Mem Skew mode this jack this jack will change to DC coupled mode to better work with modulation signals such as LFOs, envelopes and sequencers.
Principal Osc CV Input
This jack is external CV control of the Principal Oscillator pitch, tracking 1V/octave when the Modulation Osc CV knob is set to max (preset value.
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- Modulation attenuation CV in
- Modulation oscillator CV and Audio output
- Principal oscillator outputs
- Morph CV in
- Warp CV in
- Modulation oscillator FM and CV in
- Principal audio FM and CV in
Modulation Osc CV Out
This is the DC coupled output of the Modulation Oscillator spanning approximately 0 to 8.6V. This output is very suitable when using the Modulation Oscillator as an LFO to modulate other module.
Modulation Osc Audio Out
This is the AC coupled output of the Modulation Oscillator. Use it when you’re patching the Modulation Oscillator as an ordinary oscillator to external filters and such.
Principal Osc Audio Dual Out
These two identical AC coupled outputs are the main outputs of the Buchla 259e where the resulting waveform of the Principal Oscillator is heard.
Due to its complexity, patching the 259e can be pretty challenging but also great fun.
Here are some interesting patch-scenarios for you to try out:
Building Filter-Like Effects With 259e
Morphing between a timbre bank with little harmonics and a timbre bank with lot of harmonics can give the you the illusion of a filtered sweep. Try for example using green timbre bank 1 and red timbre bank 3 for a sine to square like sweep. Experiment with different warp amounts to give the red timbre part different harmonic content.
Synced Modulation
The fact that the Modulation Oscillator can be synced to incoming MIDI note messages and slaved to the Principal Oscillators pitch makes it interesting for audio rate modulation of pitch, Morph and Warp. Try for instance to have the Modulation oscillator to rapidly Morph the Principal Oscillator banks while in pitch track mode.
Use a envelope generator gated from a MIDI to CV module to sweep the Modulation Index and this will create a chorusing motion in the harmonics of the Principal Oscillator output.
Modulation Oscillator As External LFO
The Modulation oscillator can of course also be used as a ordinary LFO that can control external modules such as another 259e via its modulation (blue jack) and audio (silver jack) outputs. Using the Modulator Oscillator as LFO you can take advantage of the MIDI note on reset if you for instance would like a tremolo effect that will sound exactly the same for each note.
Using Aliasing As A Desirable Effect
The principal oscillator on the 259e has a pretty gritty, nice sound full of gorgeous aliasing in the upper regions. This can be used as a great source of metallic sounding effects, hihats, gongs etcetera.
Using The Modulation Oscillator As Main Oscillator With Hard/ Soft Sync
The Modulation Oscillator can of course also be used as main audio source. Especially the hard- and soft-sync features add new and exciting harmonic possibilities not offered by the Principal Oscillator. The Buchla 259e sync options do not sound like the other oscillators and have highly musical qualities.
Skew In Practise
The 259e’s timbre banks A,B and C enable a special Memory Scan mode where parts of the 259e internal program memory is played back as audio through the Principal Oscillator outputs. In this mode, Warp will set the scope of swept memory and the FM in knob (Mem Skew) will set the offset (i e reference point in memory), where incoming CV 0 to approximately 5.88V will sweep portion of the memory around the set offset. The 259e for Modular has been modified to be used with DC signals which makes it possible to for example very precisely sequence Mem Skew positions with a CV sequencer.
Drones
The dual timbre banks of the Principal Oscillator coupled with the built-in modulation of the Modulation Oscillator makes the 259e ideal for creating long, evolving and exciting drone sounds. Just add a couple of slow LFOs sweeping Morph, Warp, Modulation Index as well as Mem Skew inputs and you’ll have a killer drone in no time. Just add reverb.
Creating thundering bass sounds
By mixing the audio outputs of the Modulation Oscillator and the Principal Oscillator and slightly detuning them, the core basis for great bass sounds can easily be created. Use a lowpass filter like the Doepfer A-108 VCF8 or the Doepfer A-101-2 LPG to further filter out high frequencies and get a pronounced bottom end.
All in All: The Buchla 259e is a very creative and musical module that will bring you many hours of pleasant music making. Have fun!
Oscar Öberg – Modeling, project management, validation
Kristofer Ulfves – Presets, validation, user manual
Igor Miná – User manual layout, hardware photos
Todd Barton – Testing, presets
Patrick Detampel – Testing, feedback
Henrik Andersson Vogel – Marketing
Bitplant – Graphics