Introduction
Features
- MIDI input and output
- MIDI CC control of cutoff and resonance. For CS15 and CS30: independent control of both filters
- Additional LFO for each filter with multiple waveforms and optional MIDI clock sync
- Velocity and aftertouch can be linked to cutoff, LFO amount or LFO frequency
- CS30: Sequencer can be clocked via MIDI clock or a MIDI note. Adjustable MIDI clock divider with many options
- CS30: Extended note range for MIDI input
- MIDI CC control of all additional parameters
- Built-in configuration menu to quickly set many additional parameters
- Easy to install: Requires soldering, but no traces need to be cut
- Fully additive: does not change the behaviour or sound of the synthesizer unless desired.
- Low latency ?
- Optional hardware MIDI controller for hands on control of the additional parameters/li>
- Firmware update via MIDI Sysex
MIDI note control
CeeS adds MIDI input and output. In both cases, the MIDI channel can be set, or the MIDI connection be turned off.
In case of the CS30, the MIDI input has an extended note range with 5 additional note below the lowest F.
The MIDI input is monophonic and behaves exactly like playing on the keyboard. The ‘highest note’ priority is preserved.
The MIDI output is polyphonic to an extend: In certain situations, the CSxx keyboard IC stops reading low notes. More about this below.
Filter control
CeeS provides MIDI CC control of filter cutoff and resonance for the filter (CS10) or both filters (CS15, CS30).
The MIDI cutoff control is additive to the existing cutoff setting.
The MIDI resonance control is subtractive to the existing resonance setting.
Additional LFOs
Two additional LFOs are implemented, one for each filter. The LFOs feature
- MIDI control of all parameters
- Multiple Waveforms: Triangle, Rising sawtooth, falling sawtooth, square and S/H
- Free running mode, frequency adjustable between 0.13Hz (8s period) and 750Hz on a logarithmic scale
- Can run synced to MIDI clock with 18 different dividers
- Adjustable LFO-Delay and optional phase reset
- Velocity and aftertouch can be linked to LFO depth and speed
CS30 sequencer sync
CeeS allows the CS30 sequencer to be synced to MIDI in two possible ways:
- Synced to MIDI clock with adjustable clock divider
- Triggered by MIDI note 0. Each time the note is played, the sequencer advances one step
It is possible to set the sequencer clock source via MIDI CC, or in the configuration menu.
By default, the clock source is set to the internal clock of the CS and the sequencer can be used with the START/STOP button and CLOCK SPEED knob.
Velocity and aftertouch link
MIDI velocity and aftertouch can be each linked to one of the following parameters:
- Filter 1/2 cutoff
- Depth of the additonal filter LFO (1 or 2)
- Speed / or clock divider of the additional filter LFO (1 or 2)
These controls are additive to the existing filter cutoff or LFO parameters.
There is also an additional depth control for both the velocity and the aftertouch link.
Configuration Menu
By pressing a special key combination on the keyboard (all notes from F0 to C1), a configuration menu can be entered.
Here, most of the additional parameters can be adjusted on the fly:
- MIDI input and output channels
- Velocity and aftertouch link and depth
- Sequencer clock source and clock divider
The settings can be saved and will be recalled the next time the synth is powered on.
CeeS controller
A hardware MIDI controller for CeeS is available and can be used to easily control most additional parameters.
The controller features MIDI TRS and USB connections and can also be used as USB MIDI interface for CeeS.
More info on the CeeS Controller page.
User manual
Coming soon….
Installation guides
Installation guide for CS10
Installation guide for CS15
Installation guide for CS30
Peculiarities of MIDI out
CeeS is piggybacking on the original YM24800 key assigner. It reads its keyboard signals and injects its own to simulate key presses.
This approach means that we do not alter the existing connection between the keyboard and the CV generation. This has the advantage that we do not add any delay or latency – playing on the keyboard is exactly as before.
It also means that for MIDI out, we can only read a keyboard key when the YM24800 IC reads it. If it does not, we can not read it either.
As it happens, in certain circumstances, the YM24800 does not read all keys. Specifically, this happens when you start playing a high note and add multiple lower notes afterwards. After playing between 3 and 6 notes (this varies), the key assigner stops reading notes below the ones currently pressed. Higher notes can always be added.
Interestingly, this does not happen, when you start a chord by playing a low note first and then add higher notes on top. Here, we could easily send out chords with 10 notes (I don’t have more fingers, but more might be possible).
Conclusion: CeeS will not turn your CS synth into a master keyboard. But MIDI out is certainly sufficient for some situations.