Model 259e Twisted Waveform Generator
The 259e consists of two separate oscillators. One, the modulation oscillator, serves primarily to modulate the second, called the principal oscillator.
The Modulation Oscillator
The modulation oscillator has two ranges, one in the audio region of 27 to 7040 Hz; the other mostly in the sub-audio, ranging from .25 Hz to 64 Hz. Three classic wave-shapes can be selected (just one at a time), and three modulation targets can be chosen, singly or in any combination.
An F.M. input provides for frequency modulation.
Pitch tracking, when enabled, forces synchronicity with the principal oscillator. With no control voltage applied to the modulation oscillator, its pitch will track that of the principal oscillator. The offset will be zero when the modulation frequency is set to 440 Hz., indicated by an extinguished bicolor LED.
A sync facility permits synchronization to MIDI note-on messages, or to subdivisions of the principal oscillator. Hard sync truncates the waveform; soft sync uses a phase locked loop to achieve synchronization.
The Principal Oscillator
The principal oscillator generates a sine wave varying in frequency from 27 to 7040 Hz. The frequency can be modulated with an externally applied signal. This sine wave is simultaneously applied to two wave-shape tables.
Selecting waveshape tables: The selected tables are indicated with green and red LED's; changes are made with a switch that advances the selection. Short activations advance the selected tables. Pressing and holding the switch more than 1 second toggles between selecting the green and red tables.
"Memory bank" tables--a,b, and c--are actually not tables in the classical sense – they are simply portions of the operating program, full of unpredictable noise and frequent silences. (This memory is volatile, so it will be different the next time you boot up.)
When these tables are invoked, the F.M. controls labeled "mem skew" are re-assigned to table scanning functions and the F.M. inputs become table modulators. This state is indicated on some units by illuminated LED's located above the F.M. controls.
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.
Internal Bus messages and Remote Enable: MIDI messages can be received by the 259e via 1 of 4 internal busses is the module is remote enabled.
A module decodes the pitch (key #) contained in note-on messages originated by a 225e, 226h, or 218e arriving on its bus. It also responds to pitch bend messages.
Storing knob settings is also made possible when the module is remote enabled. As in all 200e series modules, the settings of pots and switches can be locally stored and subsequently recalled by the preset manager such as models 225e or 206e.
To connect or disconnect the module from this central library function, push the remote enable switch. A red LED signifies a connection.
The Internal Bus I.D. for the module is set with two DIP switches on the back of the module, and can be displayed on the 225e by holding the remote enable switch closed for about two seconds. Settings can be for A,B,C, or D. Change the DIP switch settings, reboot and hold remote enable to display your changes. It is most useful if each oscillator in a system has its own Internal Bus I.D.
Potentiometer Calibration:
Generally unneeded, there is a calibration procedure for the input potentiometers on the 259e. It eliminates the slight dependency of frequency versus knob setting for both the f.m. modulation knobs and the c.v. multiplier knobs. In other words, if you think your multiplier knobs may not be tracking correctly, you can invoke this factory calibration procedure and it may fix the problem.
• Turn all knobs counter clock-wise (CCW) – except principal OSC set to 220.
• Hold 'midi sync' button whilst you power on boat.
• Hold for 5 seconds and then release.
• There should be a constant tone generating from the 259e. After a few seconds there will be a brief drop in the sound from the tone; this means calibration has been successful.
Fun fact about 259e Revisions:
Revision 4 and below were called the 259e Complex Waveform Generator: tables 6, 7 and 8 were not memory bank tables. Revision 5 and above introduced the "memory bank" wavetables. In Don's words: "The Twisted version introduces some radically weird timbres. It is definitely not recommended for those over 25 years of age or for anyone with golden ears."