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Prototype DSP-based Digital Oscillator Module
This module includes a 32-bit DSP, high speed 16-bit ADC with multiplexer input, and two channel 16 bit DAC. On-board regulator can source 150 mA at 3.3 Volts to power external circuitry. A 50 ppm voltage reference allows the converter to operate stably regardless of power fluctuations.

Additioal peripherals can be supported with a I2C interface and a second SPI interface. A serial input and output ports are also provided.
USB Host Module Boards and Panels Arrive
The boards and panels for the USB Host module have arrived. This module adds the ability to host class compliant USB devices such as sequencers, keyboards, MIDI controllers, and memory devices to the GMS-632 or GMS-634 Programmable Interface modules. An internal power source can provide up to 500 mA. on the USB host port to power devices. It can also support externally powered hubs.

The 4 HP module (0.8 inches, 20.3 mm) comes in two color schemes and is supplied with a power and an interconnect cable.
General Purpose DSP Subsystem in a 2 Inch Square Module
A complete DSP subsystem including high speed analog to digital and digital to analog converters form the processing core of the new hybrid oscillator module. Here is a rendering of the 2 inch by 2 inch, 40 pin module:

The module has 8 multiplexed high speed analog inputs feeding a 16 bit ADC and two 16 bit DAC outputs. A variety of analog and digital inputs and outputs are provided including a secondary SPI and I2C ports and a trimmable 1V/Octave input that can be used for frequency CV control.

Hybrid VC Oscillator Features Thru-Zero FM & PM
In development is a hybrid digital oscillator that will use an NCO core to drive analog waveshaping circuits to generate sine, triangle, and pulse waveforms. FM and PM modulation inputs can be set for linear or exponential thru-zero operation.



The MU module will feature dual oscillators and VCA functions to form two complete FM operators.
USB Host Extender Module Prototype in Test
The USB Host Extender Module, GMS-632X is undergoing testing including the USB host capability and running Arduino sketches. The USB library is accessible from within an Arduino sketch and uses interrupts so the device detect, attach and eject functions continue to operate in the background while user code executes in the foreground.



Here the extender module is mounted next to the GMS-632 USB/MIDI/CV Interface module. The two are connected by a short ribbon cable with IDC10 connectors. The extender module does not require a power connector. The extender module can be used with either the GMS-632 or the GMS-634 modules.



Here the module is being used to host an m-Audio Keystation 49. Through the GMS-632 module, keypresses are converted into pairs of CV and gate signals. The GMS-632 is simultaneously connected to a laptop computer as a USB device, through which it can receive USB MIDI or program uploads.
USB Host Extender for GMS-632 and GMS-634
The GMS-632x Host Extender module adds USB Host functionality to either the GMS-632 USB/MIDI/CV Interface module or the GMS-634 General Purpose Programmable Interface modules.



The module also expands the number of analog inputs by two, each input equipped with a CV attenuator. When the input is not used, a reference voltage is applied to the attenuator so that it can be used as a control input.

The module also adds two additional gate inputs. Both USB ports may be used simultaneously.

The module is 0.8 inches (4HP) wide and does not require a power connection. It is supplied with a short jumper cable that connects it to the host module. The unit is available in black anodized with clear aluminum graphics or clear anodized with black graphics.
32 bit Processor is Core of Multi-function Module
The GMS-634EU Programmable Processor has a Teensy 3.1 processor board with a 32 bit ARM Cortex-M4 processor, USB interface, 96MHz clock, 512K of program memory and 65K of data memory. The supporting module includes two analog inputs with attenuators, two extra potentiometer-controlled voltage sources, 2 analog outputs supported by a two channel 12 bit DAC, two gate level inputs, two gate level outputs, a two channel in and out audio interface with a 24 bit 96 KHz sample rate CODEC, a standard 5 pin DIN MIDI input and output, and a 3.5mm stereo headphone output with level control.

By using the Arduino IDE with the Teensyduino add-in users of this module can download their own sketches to the module to utilize the processing power and substantially larger program space contained in this processor. A number of modular synthesizer specific sketches are available and can be downloaded and run in this module using the Teensy support libraries and some minor code modifications. In addition, libraries are provided to allow users to access the provided stereo CODEC as a high quality stereo audio input and output. The input and output jacks support -10dB line level signals.

The module can be purchased assembled or in kit form. The kit includes a Teensy 3.1 processor with pre-installed headers. The surface mount header that is used to access more of the processor I/O is also pre-installed. The CODEC board is supplied with pre-installed headers, too. The CODEC board has a socket for a mini-SD card, accessible from the rear of the module, and has been configured with SD card libraries in the Arduino environment.



The kit comes complete with all the parts and with the potentiometer leads pre-assembled. Even the solder is included. All the builder needs to assemble this kit is a narrow-tip soldering iron, long nose pliers, diagonal cutters, a small flat blade screwdriver to secure the knobs and a small or medium Phillips screwdriver. A wrench for tightening the pot and jack nuts is also recommended.

This kit includes complete instructions for assembly and is recommended for builders with intermediate kit building skills.
New Kit Recreates an Old Classic
The GMS-294a VC Low Pass Filter is a faithful recreation of the classic Moog 904a 4 Pole Transistor Ladder filter. It incorporates the same audio path and transistors used in the original filter designed by Robert Moog. The GMS-294a adds an attenuator on the audio input and an attenuated CV input as well as a 1 Volt/Octave frequency control input.

The manual resonance control causes a peak in the low pass response and if increased to near maximum will cause the filter to go into sine wave oscillation.

The 1 MU wide module is available either assembled or in kit form as shown here:



The kit comes complete with all the parts and with the potentiometer and jack leads pre-assembled. Even the solder is included. All the builder needs to assemble this kit is a narrow-tip soldering iron, long nose pliers, diagonal cutters, a small flat blade screwdriver to secure the knobs and a small or medium Phillips screwdriver. A wrench for tightening the pot and jack nuts is also recommended.

This kit includes complete instructions for assembly and is recommended for builders with intermediate kit building skills. Some calibration is required after assembly and minimally requires a voltmeter although a waveform display of some kind is helpful.
Dual DADSR Envelope Generator Has Multiple Modes
The GMS709a dual DADSR envelope generator, in addition to the normal ADSR controls adds a delay setting prior to the start of the envelope. The delay time interval can range from 1 millisecond to 10 seconds. Other panel controls can select an exponential envelope or a linear envelope with either positive or negative direction. The operating modes are Normal, Gated and Loop. In Loop mode, by adjusting the delay, attack and decay controls, the envelope generator will generate a series of envelopes with varying frequency.



The gate input connector also includes a trigger input on the ring connection so that a trigger source can restart the Attack/Decay phase of the envelope while the gate signal remains active. There is also a front panel gate pushbutton to trigger the envelope for each channel.
Adapter Allows Using Expert Sleeper ES-3 Module in MU
The ES3-MU adapter allows a Expert Sleepers ES-3 Mk II ADAT optical interface module designed for Eurorack to be housed and powered in a 5U MU format synthesizer cabinet. The Eurorack panel is removed from the module and some minor and reversible modifications made to the module. The module can then be remounted in the MU panel and connected to an internal circuit board that provides power and output interface connections to 1/4 inch panel jacks.



The module adapter also allows the user to select signal conditioning for the channel 5-8 outputs to produce an analog output or a 0-5 Volt standard gate output. Internal power supplies are connected to the module through a 16 pin Eurorack power cable. The module will be available as a semi-kit to allow current ES-3 MK II owners to adapt their modules. We will also offer a retrofit service for those people who want to obtain a completely assembled and tested unit.