Submodular Synthesizer

Introduction

The ISHIZENO ONE is a submodular synthesizer. It decouples faceplate from electronics in order to provide more modularity. It is built around an iPod Touch used as touchscreen, configuration interface, and advanced processing unit. It provides 8 monophonic channels. Each channel is supported by a modular 16-pin breakout board. Patching between the faceplate's controls and the channel's breakout board is supported by a set of analog crosspoint switches configured through the iPod Touch.

8 Monophonic Channels

Each of the 8 monophonic channels provides:

• 8 analog ports
• 2 small knobs
• 2 large concentric knobs

Any analog port or knob of any channel can be patched to any pin of the channel's breakout board. Patching can be done through the multi-touch user interface, or through a QR code printed on the breakout board and scanned by the iPod Touch's front-facing camera. Patches can also be downloaded from the Internet through the iPod Touch's WiFi connection.

16-channel Oscilloscope

The module includes two AD7606 8-channel 24-bit analog to digital converters. This allows the built-in iPod Touch to be used as a low-frequency 16-channel oscilloscope. By default, the oscilloscope's channels are patched to the input and output of every monophonic channel.

Submodular Architecture

Out of the box, the module does not provide any synthesis capabilities. Instead, these are added through breakout boards, with up to 8 boards (one per channel). The module also includes an Arduino Uno used as middleware. Programming can be done through the Arduino, through the iOS operating system of the iPod Touch, or both. Obviously, the Arduino and the iPod Touch can be used as software sequencers (among many other applications). The analog crosspoint switches can also be reconfigured dynamically in order to support high-frequency dynamic patching.

Breakout Boards

Every channel can be supported by an optional breakout board that is plugged onto the module's backplane. Breakout boards must use a standard 16-pin connection pattern that is currently being defined. One likely candidate is an L-shape arrangement of 2 rows of 8 pins (standard 2.54mm spacing). This arrangement ensures that breakout boards are always properly connected to the backplane.

The ISHIZENO submodular architecture does not mandate any specific pin assignment. Instead, the pins of breakout boards are dynamically patched through the analog crosspoint switches, which can be used for both analog and digital signals, as well as power. Because breakout boards do not include any faceplate, controls, or power connector, they should be more cost effective than full-fledged Eurorack modules. As such, they are referred to as submodules, and the synthesizer is described as being submodular.

A single-channel breakout board (1S) is 53mm long and 53mm wide. Connection between a breakout board and the backplane is achieved through stackable headers, allowing multiple breakout boards to be stacked on top of each other for applications that require many components.

Examples of breakout boards could include any of the following:

• Analog Filter
• Digital Signal Processor
• Envelope Generator
• Low Frequency Oscillator
• Mixer
• Oscillator
• Phase Shifter
• Sampler
• Sequencer
• Waveshaper
• Etc.

Multi-Channel Breakout Boards

By default, a breakout board has 16 pins and is attached to a single channel. But some applications might require breakout boards with more pins, or more PCB real-estate. In such a case, a multi-channel board can use the connectors offered by 2, 3, 4, 6, or 8 channels. For standardization purposes, single-channel boards are said to have a size of 1S, while multi-channel boards have sizes of 2S, 3S, 4S, 6S, or 8S.

• 1S: 53mm × 53mm
• 2S: 53mm × 106mm
• 3S: 53mm × 159mm
• 4S: 106mm × 106mm
• 6S: 106mm × 159mm
• 8S: 106mm × 212mm

Dynamic Patching

Dynamic patching is enabled by a matrix of 32 AD75019 analog crosspoint switches. These switches have no gain and a low 150 Ω resistance. No more than two switches are ever used in cascade, thereby limiting the overhead resistance to 300 Ω on every analog signal path.

Patching across channels can be done in a traditional way through the faceplate's 64 3.5mm jack chassis sockets, through the analog crosspoint switches, or through multi-channel breakout boards. Using dynamic patching, any of the 8 analog ports and 4 potentiometers of any channel can be patched to any of the 6 analog inputs of the Arduino Uno, and any of 8 shared analog endpoints. The latter enables dynamic cross-channel patching.

Digital Potentiometers

All knobs are connected to an AD5254 quad digital potentiometer with 256-position resolution and providing a resistance range of 1 kΩ, 10 kΩ, 50 kΩ, or 100 kΩ. This setup allows all 32 potentiometers to be controlled manually through knobs, digitally through Arduino or iOS, or modularly through traditional voltage control (with both faceplate patching and dynamic patching).

Additional Features

The faceplate also include two spinner control knobs driving rotary encoders and two USB ports, one connected to the iPod Touch's lightning connector, and one connected to the Arduino Uno. The USB ports can be used to connect controllers like keyboards or grids.

Project Status

This module is at the early prototyping stage. Specifications will vary. All software will be released under an open source license and all hardware designs will be released under a Creative Common license. Unfortunately, no release timeframe can be announced at this point.

Additional Resources

• List of Parts

Feedback welcome!

https://ishizeno.wordpress.com/

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• ? mA -12V
• ? mA 5V

No info about availability.

$1,995