The B500 Sampling Keyboard models a sampler from the mid ’80s, with 4-voice polyphony and multi-channel note memory. The audio engine and user interface are based on the Casio SK-1. Many DIY enthusiasts have taken advantage of the affordability of this synth and pioneered circuit modifications to manipulate ROM address and data outputs for a variety of otherworldly sounds; a practice that has since been coined circuit bending.
Section Details
1 Volume
Increasing volume above 50% engages speaker distortion with Internal Speaker blend greater than zero.
2 Internal Speaker
Sets blend between Direct output and Internal Speaker emulation.
3 Operation Modes
- Normal mode is the default mode of operation, supporting 4-voice polyphony.
- Solo modes 1 and 2 each provide separate monophonic voices, supporting different tone selection.
- Chord mode splits the keyboard and engages 3 or 4 note diatonic chords from F3 to C5, with chord type specification from C#5 to C6. Refer to synth labeling for chord type per note which includes: major, minor, 7th, minor 7th, minor-major 7th, augmented, diminished, suspended 4th, augmented, 6th, minor 6th, and half-diminished chords. If no type is supplied, chords default to major.
All modes can be sequenced via note Memory, refer to Section 10 below for details.
4 Effects
- Vibrato engages subtle pitch bending after an initial delay.
- Portamento bends each note up or down to pitch depending on if an existing note is being held below or above the played note.
5 Circuit Bending
Tapping the Circuit Bending button opens a new window containing three sections corresponding to Analog, Digital, and Clock sections of the internally modeled circuit. A fixed set of bend points have been provided that can be dynamically connected or configured with a wide variety of results mimicking actual bends on a ROM-based synthesizer.
Note that inter-section connections are unidirectional with respect to the point of origin. If a bend connection is modified, wire color will change to reflect routing from the source to a new destination. This allows for independent control of analog-to-digital or digital-to-analog bends, with each direction providing a unique effect.
6 Envelope Select
Tapping the Envelope Select button highlights the currently selected volume envelope. Each accidental key on the main keyboard represents a different envelope. Envelopes are pre-programmed with each tone and can be modified and saved in a preset. The display bar above the keyboard contains visual representations of each envelope type.
7 Synthesized Tone
Tapping the Synthesized button selects the synthesized tone, which defaults to reference pitch.
Tapping the Synthesizing button opens the drawbar which overlays partial values above the specific subset of natural keys that control each partial. These keys can be tapped or dragged to change the level of each partial from values 0 to 15. Each partial is labeled based on traditional organ pipe lengths from 16′ to 1′.
Note that synthesized tones are internally generated and are not impacted by Circuit Bending.
8 Sampled Tones
What else is there to say? These sampled tones are classics, we hope you enjoy them!
Note that selecting a sampled tone loads a pre-programmed envelope, and re-selecting the same sampled tone will re-apply this envelope. Envelopes with sustain or longer decays than selected sample length will loop automatically.
9 Rhythm
Tapping the Rhythm button highlights the currently selected beat. The lower section of the drawbar shows each available beat for the specific subset of natural keys that apply. Changing the beat is instantaneous and can transition mid-measure during playback. Tapping Tempo buttons changes BPM by +/-10.
Tapping the Fill-In button plays a preset fill with custom duration based on the selected beat. Fills transition mid-measure and will play to the end of the current measure, or the next full measure when tapped within a 1-2 beat grace period at the end of the current measure.
10 Memory Sequencing
Tapping the Memory button opens a new window containing a score-based view for recording simple melodies. In Normal mode, melodies can contain four note harmony, in Multi-Channel mode (Solo 1/2, Chord), melodies are monophonic or fixed diatonic chords.
Melodies can be manually entered using Note Length and Insert Rest for composition. Melodies can also be recorded live which may provide a less accurate notation for the performance but will play back exactly. Delete removes the current or previous note based on cursor position. Clear erases the entire sequence on the selected staff.
When recording live, rhythm always plays back to provide a reference for the beat. During manual playback, Sync Rhythm can be enabled so that the beat starts during playback. Enabling Repeat sets a loop point at the end of the last measure with playable notes.
Note that after programming and/or recording a melody, the Lock icon above the title bar can be enabled to ensure further edits are disabled.
Continuous Sampling
- Continuous sampling for realtime glitch effects
- Sample loop editing for time and pitch manipulation
- Single or multi-part sequencing for sample playback—combine with continuous sampling for additional chaos
Tapping the Continuous Sampling button engages a live sampling mode where the buffer used for playback is taken directly from stereo audio input. By default the buffer plays back at a normal rate, reproducing the original signal, slightly degraded by the limitations of the internal sampler. In addition to this, the keyboard or Memory sequencer can be used to trigger buffer playback at different sample rates. And in addition to that, Circuit Bending can be employed on sample buffer playback. With full stereo support.
Note that this mode is independent of the traditional internal mono sample buffer that can be used to capture and store samples for playback and manipulation.
11 Sampling
Tapping the Sampling button opens a new window containing an oscilloscope-style view for capturing samples and setting the loop point. Instructions to operate are as follows:
- Drag the Threshold (horizontal line) up or down to establish a reasonable threshold slightly above the noise floor
- If needed, adjust Gain and/or Range to set input level
- Engage by tapping Record which transitions to an Armed state
- Once the input signal exceeds the threshold an internal 1.4s buffer will fill with audio data
- Drag the Loop Point (vertical line) left or right to establish where sample playback will stop and/or loop
By default, Left and Right inputs are summed to a mono, however Left or Right can be selected independently. Use Monitor to listen to sounds before and/or during recording. Dir/Mic sets blend between Direct input and Internal Microphone emulation.
By default, playback is normalized to A4, however Tune can be adjusted +/- 12 semitones to extend range or assist with tuning.
Audio Unit Operation
- Section 9: Sync DAW Tempo
In addition to the specified controls above, a new button is made available when running SynthStamp as an audio unit. The Sync DAW Tempo button is provided which enables continuously tracking DAW BPM rates so that rhythms can be synchronized with DAW recording and playback.
