Introduction Rainbow is Big Tick's software synthesizer for Microsoft Windows. It can be used either as a standalone synth, or as a plugin, based on VST 2.0 specifications. It can be downloaded at http://www.bigtickaudio.com Thanks to an original mixture of FM, AM, additive and substractive synthesis techniques, Rainbow is able to produce a wide assortment of sounds, from analog emulations or synthesized drums to 80's electric pianos and synth basses. Rich stereo sounds can be created in a minute thanks to the built-in chorus. And, don't forget the step-sequencer for this arpeggiated, drone lines! Finally, a high-quality oversampling mode allows to generate.wav files without any aliasing artifacts. Credits Rainbow is copyright (c) 2000 Big Tick VST Plugin-In Technology by Steinberg. VST is a trademark of Steinberg Soft- und Hardware GmbH 1 of 12 7/6/10 7:23 PM
Special thanks to: - Bram de Jong for his constant support and beta testing - Charles Kirk for testing Rainbow with Logic, and for the wonderful bank3. System Requirements The plugin version requires a VST-compatible host. This program has been tested with Cubase VST 3.7, Logic Audio Platinum 4.6.2, and Orion 1.0. If you intend to use it with Logic, please note that Logic implementation of parameters automation will prevent you from automating parameters after the first 64 ones. The standalone version requires a soundcard with DirectSound drivers, and a midi controller. History of changes Version 2.2 - Fixed some nasty clicks - Slight performance improvements Version 2.1 - Support for panning and sustain automation - Now works fine in Logic Audio platinum 4.6.2 - Can load/save patches in the host native format (fxb or pst) Version 2.00 - New graphics engine with skins support - double-mode and bandpass filter - Phase knobs - Monophonic and 'finger' modes - Midi out option - Lots of bug fixes! Version 1.80 - Added step sequencer - Added stand-alone mode - Added "freeze" option - Added a new bank of 32 programs - Many annoying bugs fixed! Version 1.70 - Added stereo chorus - Added control of filter cutoff by velocity - Minors layout changes (to fit the above additions into the interface). - Audio out sliders are moved into the oscillators blocks, and all sliders now have a LED display. - Changing an oscillator pitch displays its scaling compared to base pitch Version 1.63 - First public release At a glance: Rainbow features Polyphony 1 to 4 oscillators per voice, up to 24 voices, depending on cpu power. Oscillators Selectable shape (sine, saw, square, triangle, noise) 2 of 12 7/6/10 7:23 PM
Coarse / Fine tuning knobs, with selectable keyboard tracking mode. LFO mode. Distorsion (Waveshaping) and phase knobs APDSR (Attack/Peak/Decay/Sustain/Release) level enveloppe. Control of the level by midi velocity and/or key position. Frequency and Amplitude modulation controls Filter Selectable Lowpass, Bandpass or Hipass filter, with cutoff and resonance knobs. 'x2' (4 poles with 2 filters in series) mode APDSR enveloppe and env mod knob. Control of cutoff and/or resonance by midi velocity Other features APDSR pitch enveloppe Portamento Stereo chorus Built-in step sequencer. Monophonic mode. High-quality oversampling mode with antialias filter Fully customizable user interface. Midi implementation Rainbow is fully midi-controlled. Moreover, all controllers can be customized to fit your existing hardware. Installation Notes - Double-click on the setup file. - Select your installation directory. By default this directory is \Program Files\Big Tick\Rainbow2. This is the location where all data required by Rainbow (wavetables, banks, configuration files) will be installed. - Select your 'start menu' group. This is the place where you will find a link to Rainbow standalone version and documentation, in your Windows start menu. - The installer then copies Rainbow files into your chosen installation directory, and proceeds with wavetables generation. Generating wavetables Rainbow uses high-quality wavetables to store the default square, saw, triangle, and sine waveforms. You are given control over the quality of these wavetables: 3 of 12 7/6/10 7:23 PM
The 'table length' parameter selects the size of an individual wavetable. It should be set to the highest possible value (4096) for best sonic results. The 'max tables/octave' parameter selects how many wavetables will be generated, if required, per octave. Again, it should be left to 12 for best results. Changing any of these parameters displays the estimated required memory. This allows you to tweak the wavetables quality to meet your memory requirements. Plugin installation Finally, the installation program will ask for the location of your vst plugins directory. If you only want to use Rainbow as a standalone synth, hit 'cancel', otherwise specify the proper location, and the installer will copy the plugin file there. Using Rainbow The Oscillators Rainbow synthesis engine can use up to 4 oscillators per voice. All oscillators offer the same set of controls. Waveform selection Oscillators can produce one of 5 waveforms, among: sine, saw, triangle, square, or noise. The waveform is selected using one of the 5 buttons at the bottom of the oscillator panel. Waveform modifiers Next to the waveform selection buttons, the 3 waveform modifiers buttons allow to: - randomize the initial phase of the oscillator. - rectify (take the absolute value) of the oscillator. - negate the oscillator. The picture below displays the waveform for a rectified sine wave oscillator. Waveshaping distorsion The WS knob is used to distort an oscillator, by applying a square-like waveshaping curve. The following pictures show the effect of sweeping the WS knob from 0 to 127 on a sine wave oscillator. 4 of 12 7/6/10 7:23 PM
Oscillator pitch The oscillator pitch is controlled by the right-part of the oscillator panel: - The keyboard button selects the keyboard tracking mode. When engaged, the oscillator pitch follows the played note. When disabled, the oscillator pitch is constant. - The "Coarse" knob controls the pitch of the oscillator, by intervals of a semitone. - The "Fine" knobs allows to detune the oscillator, from -0.5 to 0.5 semitones. - The "lfo" button turns the oscillator into low frequency mode (by dividing its frequency by 1000). Note: when lfo mode is engaged and both Coarse and Fine knobs are set to 0, the oscillator is "frozen". This means its value won't change over time. This unusual feature is very useful to create pulse-width modulation effects (where a frozen oscillator is entirely driven by another oscillator, using Frequency Modulation). When changing the pitch settings of an oscillator, some useful pitch information is displayed to the right of the patch name screen: for fixed pitch oscillators, the frequency (in Hz.) is displayed. If keyboard tracking is enabled, the ratio of the pitch (compared to the base pitch) is displayed. This information is very useful for FM programming. Levels The oscillator level is controlled by the main level (green) knob, and the APDSR (Attack, Peak, Decay, Sustain, Release) enveloppe. Attack, Decay and Release times can range from 10 ms to 5 seconds. Levels modifiers In addition to the enveloppe level, the VS and KS knobs are used to modify the level depending on the midi note velocity or number: The VS knob controls how much the midi note velocity affects the overall oscillator level. When VS=0, the oscillator level does not depend on the note velocity. When turned up to 127, the note velocity fully modifies the oscillator level, so that a note played at velocity 1 will be barely audible, while one played at velocity 127 will play at full volume. The KS knob allows to control the oscillator level depending on the played note position: when 0, the lower end of the keyboard is louder. When 64, all notes have the same level. When 127, high notes are louder. Main output Because of the synthesis method used in Rainbow, you won't want to route all oscillators to the audio output. For instance, LFO mode oscillators are more useful as a modulation source than as an audio output. The big slider to the left of the block allows to select the audio mix of the oscillator. 5 of 12 7/6/10 7:23 PM
Frequency modulation (FM) Any oscillator can have its frequency modulated by any other, including itself (feedback). How FM works FM in Rainbow should more accurately be called "Phase Modulation", as internally, FM is actually the value of an oscillator phase. More accurately, the pitch of an oscillator depends on 2 values: - The "base pitch", determined by the coarse and fine knobs (and lfo mode button) - The "phase" or "fm" value, determined by the FM matrix. It would be out of the scope of this documentation to describe the theory (and the maths) behind FM synthesis, it is enough to know that, when an oscillator is FM-modulated by another one: - New harmonics appear below and above the modulated oscillator base pitch. - The new harmonics depend on the ratio between both oscillators pitches: if the ratio is an integer, harmonics will be multiple of the base pitch. Otherwise new tones will appear. - When an oscillator self-modulates itself (feedback), it usually creates very low harmonics. This is suitable for creating very deep basses. FM controls Every oscillator has a set of 4 sliders, defining the Frequency Modulation amount from the 4 oscillators. Amplitude modulation (AM) Another way to have the oscillators interact with one another is to use amplitude modulation. This synthesis method is very useful for creating metallic timbres, combined with the filter and the stereo chorus, it can create very interesting ambient textures. How AM works Amplitude modulation is used to multiply 2 oscillators together. This can be used for several effects: - If one of the oscillators is in lfo mode, it will change the overall level of the other oscillator. - Otherwise AM will create new harmonics, leading to strange (and often beautiful) effects. When applied to 2 sine waves the harmonic results is the sum and difference of the initial oscillators, but when using more complex oscillators, the result will have a very complex harmonic contents. AM Controls For each oscillator, a row of 4 buttons allow to select one or several oscillators that will be used as amplitude modulations sources. An oscillator can even AM-modulate itself! The Filter The audio output mix, after applying FM and AM, is sent through a resonant filter. Filter settings 6 of 12 7/6/10 7:23 PM
The hb, bp and lp buttons are used to select the filter type (highpass, bandpass or lowpass). The x2 button sets the filter into 'double' mode (basically, it uses 2 identical filters in series). The cutoff and rez knobs select the cutoff frequency and amount of resonance. Filter enveloppe An Attack / Peak / Decay / Sustain /Release enveloppe can be applied to the filter cutoff. The Env Mod knob selects the amount of modulation from the enveloppe. Velocity Control The VS.R knob is used to select how much the midi note velocity controls the filter resonance. When set to 0, the value of the rez knob is used whatever the midi note velocity. When turned up to the max, high velocity notes will have a resonance close to the one selected by the rez knob, while low velocity notes will have almost no resonance. The VS.C knob, new in version 1.7, works similarly, but with the cutoff frequency. The pictures below illustrate the effect of the filter, with various settings, when applied to a 22 KHz noise signal generated by rainbow: Lowpass Filter No resonance With resonance With resonance, x2 mode Highpass Filter No resonance With resonance With resonance, x2 mode Bandpass Filter No resonance Average resonance High resonance Pitch enveloppe and Portamento Below the filter settings are global pitch controls: Pitch Enveloppe 7 of 12 7/6/10 7:23 PM
The 5 familiar knobs define the global pitch enveloppe of the sound. Peak and Sustain values range from -12 to +12 semitones. The default value (basic pitch) is 64. Portamento When the glide button is toggled on, portamento is activated. With this effect, new notes "slide" from the pitch of the last played note. The time taken for sliding is controlled by the time knob. Mono mode When the mono button is toggled on, the synth is in monophonic mode: existing notes will be cut off when new ones are played. This mode can be useful to play portamento effects. Finger mode When the finger button is toggled on, in combination with the glide button, portamento will be activated only when notes overlap (playing staccato won't activate the portamento). This feature is very useful for this classical 'bassline' sound. Stereo chorus A stereo chorus, made of two sweeping delay lines with cross-feedback, was added in version 1.7 (note: this is a the little brother of our Hexaline plugin, a free chorusing effect that you can download from our web site). The audio output is delayed by two independant delays, whose delay time is controlled by a LFO. The output of each delay is then fed back into the other one. This feature can give the sound more depth and presence, or create phasing effects. Used with extreme feedback settings, it can generate beautiful ambient textures, even from simple sources. The top line of knobs controls the left delay line, the bottom one controls the right one. Delay knobs control the minimal delay amount (from 0 to 50 ms). Depth knob control the range of the lfo (from 0 to 50 ms). Speed knobs control the LFO rate (from 0 to 50 Hz) Feedback knob controls the amount of feedback (from -1 to +1). Extreme feedback values are possible, but should be reserved for special effects. Finally, the 'out' slider controls the amount of chorused signal that is mixed into the audio output. Setting it to zero bypasses the chorus entirely (thus saving some cpu). Step sequencer New In version 2.0 is the step sequencer. This sequencer allows to trigger a little sequence whenever a note is played. This is a wonderful feature for this classical "arpeggiator" sound, or for building hypnotic patterns. The little green lights to the bottom left are switches that allow to turn the step sequencer on and to select the speed of the sequence. Note that the speed is always dependent on the current tempo. The 16 knobs are used to define the notes that are going to be played in sequence. The buttons below these knobs allow to define the length of the sequence. The "length" knob selects the duration of the notes of the sequence. Don't crank this one up too much or you'll generate a lot of notes, thus using all the cpu. Finally, the 'random' knob is a little gem that makes the sequencer pick a random note into the sequence at each step. You can hear it in action in the 'PleasureDrone' demo patch, in file bank2.bnk. Miscellaneous 8 of 12 7/6/10 7:23 PM
The last part of the synth consists in a display with the current patch name. Whenever a value is changed, the midi controller and the new value are displayed below the patch name. Oversampling The "x2" button toggles oversampling. This cpu-intensive feature should be used when rendering the synth output to WAV files, to achieve the best possible quality. DC removing The "DC filter" button toggles the DC filtering. This feature removes any offset that might be present in the output signal, and can be useful if rectified oscillators are sent into the audio mix. MIDI out The midi out button selects the behaviour of Rainbow regarding automation: when turned on, Rainbow sends automation information to the host using midi controllers. When off, the regular vst parameters automation is used. In standalone mode, turning it on allows Rainbow to send midi controllers to the selected midi output whenever a parameter is changed. Tempo knob The Tempo knob allows to select the default tempo for the step sequencer. When turned to the right to the maximum (127), the sequencer uses the tempo of the host application. Otherwise the actual tempo is displayed under the patch name. MIDI controls All parameters can be controlled via MIDI. Instead of hard-coding a knob or button to a fixed parameter, we use the rbctrl.ini file, located in your installation directory, to define which MIDI controller goes to which knob. This file is also used to define the names of Rainbow internal controls. You can modify this file if you like (for instance, if you'd like to change the controllers assignments), but if you do, never change the order of the controls! Banks and Patches Rainbow writes sounds into 2 types of files: Patches are the parameters for a single sound. Banks are a collection of 32 Patches. In version 2/0 you have 4 banks (bank1.bnk to bank4.bnk). The last one can only be loaded by registered users. Loading new sounds Right-clicking anywhere in the window opens a menu, where you can: - Display information about Rainbow. - Load a Bank (a collection of 32 Patches) or a single Patch. - Save a Bank or a single Patch (registered users only). - Go to any Patch in the current Bank. - Write the current Patch to any location in the current Bank. Saving your work: important note Rainbow actually holds 33 patches: the 32 ones of the loaded Bank, and the one being edited. This means, when you 9 of 12 7/6/10 7:23 PM
change the parameters of a sound, the initial patch is not modified (you are actually working on a copy). If you want to save your work, you have to write the patch onto a location in the internal Bank. This is done by selection the "write" option in the right-click menu. If you don't write your changes into a Patch in the internal Bank, your changes will not be saved with the bank when you select the "save" option. However, the "save single patch" option works on the patch currently being edited. The same applies to the "load single patch" option. Keyboard shortcuts Rainbow can handle the following keyboard shortcuts (depending on the host you are using, not all of these will be available, as some hosts - Logic Audio being the most famous one - prevent plugins from receiving keystrokes): '+' and '-' keys allow to finetune a control value. You can enter a controller value directly using the numeric keypad 'f' key, on a 'coarse' or 'fine' knob, allow to enter an oscillator frequency in Hertz. '*' key, on a 'coarse' or 'fine' knob, allow to enter an oscillator frequency, as a multiple of the base frequency. 'w' key allows to write Rainbow output to a.wav file (standalone mode only) 'i' key brings up the setup dialog (standalone mode only) Right-click menu The right-click menu allows to: Load and save bank or patches (note that saving is only enabled in the registered version) Clear the current patch 'Freeze' Rainbow (so that it will not react to program changes sent by the host) Standalone mode 10 of 12 7/6/10 7:23 PM
Rainbow can run as a plugin in a vst-compatible host like Cubase or Logic, or as a standalone application. In this latter case, it requires a midi keyboard to be plugged into one of the system midi inputs. It can then be played as a realtime synthesizer. Standalone setup The very first time you run the standalone version, you will get the following setup screen. This dialog box allows to configure the standalone version of Rainbow: audio device is the DirectSound audio device that will play the output sound. You can choose to use the primary DirectSound buffer, which will allow you to get a lower latency (but then you will not be able to use other audio applications while Rainbow is running) sample rate is the output audio sample rate. Make sure you select a sample rate compatible with your soundcard. latency determines how much time elapses between the time you press a key on your midi controller, and the time the associated note is played by Rainbow. Normally you will want this figure to be as low as possible, but you will have to tweak this parameter until you find the value that works best with your hardware configuration (not all soundcards are equal when it comes to latency values). Midi settings should be familar, they allow to select which midi port will be used to trigger Rainbow. Midi output is used if you want Rainbow to generarate midi controllers whenever a knob is tweaked. 11 of 12 7/6/10 7:23 PM
Default Tempo selects the default value for the tempo. This value is used with Rainbow step sequencer, when the internal tempo is set to 127. Programming your own sounds Beginners tutorial: single oscillator synth This first tutorial is for new users who would like to get started in programming sounds with Rainbow. Setting up the oscillator - Clear the current patch using the right-click menu - Enable oscillator 1 by selecting a sine wave shape. - Set oscillator level to the maximum. - Set oscillator audio level to 24. This routes the oscillator into the audio out, without changing its level. - Set oscillator pitch settings: coarse=12, and fine=64. - Toggle keyboard tracking on. If your host is set up to send midi data to Rainbow, playing notes on a keyboard should now play a basic sine sound. Adding feedback While still playing notes, slowly turn up the first knob of the Frequency Modulation matrix till about 75. Hear the changes? What you are doing is adding some FM from oscillator 1 into itself. This creates a much more interesting timbre. Filtering the sound We're now going to send this audio into Rainbow's resonant filter: - Enable the lowpass filter. - Set cutoff to 64, and rez to 80. - Add a filter enveloppe: Attack=10, Peak=127, Decay=100, Sustain=50, Release=0 - Set Env Mod to 127 Adding Portamento - Turn "glide" on. - Set glide time to 40. In this example we have only used one oscillator out the 4 provided by Rainbow. You should now try to add a second, detuned one for a bigger sound... Then maybe, use another one to add an attack part? And what about using the 4th one as a sub-oscillator for a monster bass sound? We know Rainbow can look a bit intimidating with all these knobs and sliders... Included are four banks of 32 patches, varied enough to demonstrate the potential of Rainbow as a synthesis tool. You will probably come up with new interesting effects by experimenting from these, if you do, don't hesitate to send us your patches... 12 of 12 7/6/10 7:23 PM