CeeS upgrade for Yamaha CS10, CS15 and CS30 Synthesizers

video upload by Tubbutec

"CeeS is an upgrade for Yamaha CS10, CS15 and CS30 synthesizers. It adds MIDI input and output as well as additional filter modulation sources."

https://tubbutec.de/cees/

CeeS is an upgrade for Yamaha CS10, CS15 and CS30 synthesizers. It adds MIDI input and output as well as additional filter modulation sources.
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: ~1ms
Optional hardware MIDI controller for hands on control of the additional parameters
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.