DIY - FOR EXPERIENCED BUILDERS - PCBs ONLY

The unit is designed for a modular synthesizer and a computer with a DAW such as Ableton Live, and/or a MIDI keyboard with a DIN cable and/or a MIDI-USB music keyboard.

This module will play four polyphonic voices. Each voice can be autotuned. Autotuning will customize the voltages sent to each voice to compensate for any tracking errors in the VCOs. After the autotune process, each VCO will receive CVs that will allow it to play notes that are separated by 1/12 octave. And all four VCOs will be in tune.

For example, if one of your VCOs tends to become flat as it reaches higher frequencies, the autotune feature will automatically send a higher CV to that VCO to compensate for the scaling error. Each VCO in the bank may be compensated differently so that they remain in tune as the full frequency range is accessed.

The autotuning will get your VCOs very close but if you are looking for very high precision tuning this is not the module for you. The user interface is complex (although fully documented) so if you are experimenting with polyphony on your modular then you will enjoy the module.

IMPORTANT NOTE

This is a PCB and Panel set only. A set of 2 high quality PCBs, 1 front panel, pre-programmed PIC microprocessor ONLY are included. You will need to purchase your own components and build your own module. Comprehensive build instructions and BOMs are provided to help you source the components needed and we even provide links to shopping carts to simplify sourcing those components. Some product photos above show COMPLETED build.

THE PROGRAMMED PIC PROCESSOR IS INCLUDED!

KEYBOARDS

Use this module to connect a range of popular USB MIDI keyboards:

• Roland A-49
• Arturia MiniLab MKII
• Arturia MiniBrute
• MidiPlus AKM 320
• M-Audio Keystation 49
• M-Audio Keystation 61
• WORLDE Panda MINI 25-Key Ultra-Portable USB MIDI Keyboard

and directly play your analog modular synthesizer. Polyphonic and monophonic operation.

Construction

Build it yourself - FOR EXPERIENCED SOLDERERS ONLY - This is a set of 2 high quality PCBs and an optional front panel ONLY for users who want to purchase their own components and build their own module. Some product photos above show COMPLETED build. The pre-programmed PIC microprocessor is included with the PCB set.

Features

• 4 outputs supported which can drive 4 synth voices

• Command mode enables various functions to be performed using the keys

• POLYPHONIC PLAYING MODE - play 4 notes polyphonic using up to 4 synth voices

• MONOPHONIC PLAYING MODE - the device will play monophonically with the same note playing on all 4 outputs

• Various split-keyboard modes allowing you to group the outputs for better control of key shifting

Connections

1. You can connect a DIN keyboard using the TRS jack. You will need a MIDI/TRS Type A cable or a MIDI/TRS Type B cable depending on how you have configured the jumpers.
2. You can connect a USB keyboard. The device will operate as a USB host and power the keyboard on its USB bus while receiving MIDI data from the keyboard.
3. You can connect the module as a USB device using a computer or other host connected to the module's USB-B type socket. This connection will be used for connecting your DAW, such as Ableton Live, to the module.
4. The CV and GATE outputs go to each of the 4 voices in your modular.
5. The SIG IN jacks are for connecting a pulse output from each VCO that is to be autotuned.

Playing modes

Mode 0: Omni On/POLYPHONIC. Standard mode. It receives channel messages sent on any channel and plays notes polyphonically. The device will play 8 polyphonic voices. The device responds on ALL midi channels.

Mode 1: Omni On/MONOPHONIC. It receives channel messages sent on any channel and plays notes monophonically. The device will play monophonically with the same note playing on all 4 outputs. The device responds on ALL midi channels.

Mode 2: SPLIT-LOW-POLY MODE. The device will play 3 polyphonic voices on outputs 2-4 for keys on and below the split and monophonically on output 1 for keys above the split. The device responds on ALL midi channels.

Mode 3: SPLIT-HIGH-POLY MODE. The device will play 3 polyphonic voices on outputs 2-4 for keys on and above the split and monophonically on output 1 for keys below the split. The device responds on ALL midi channels.

Mode 4: SPLIT-POLY-POLY MODE. The device will play 2 polyphonic voices on outputs 1-2 for keys on and below the split and 4 polyphonic voices on outputs 3-4 for keys above the split. The device responds on ALL midi channels.

Mode 5: Omni Off/POLYPHONIC. It receives channel messages sent on ONE specified channel and plays notes polyphonically. Now the device will play 4 polyphonic voices but the device responds only to the selected midi channel.

Mode 6: Omni Off/MONOPHONIC. It receives channel messages sent on a set of specified channels and plays notes monophonically. Now the device will play monophonically, with each input midi channel mapped to one output channel. The initial midi channel sets the midi channel that will output from the device on channel 1. The remaining 3 outputs will be assigned consecutively starting with initial midi channel +1 etc.

Autotuning feature

Plug the pulse output of each VCO to be autotuned into the corresponding SIG IN jack. Plug the corresponding CV of the Auto-Midi into the CV input of each VCO to be autotuned. Plug the corresponding GATE of the Auto-Midi into the GATE input of each EG in the voice to be autotuned.

The auto tune process will move through each of four voices until complete. If a SIG IN is not present for a voice the auto tune will skip that voice after a few seconds.

Construction

The module (when using our front panel) is Eurorack size and only 8HP wide leaving room in your rack for other modules. With the PCBs only, you can wire any pots and jacks to your own front panel or standalone case.

Further details

If you are a composer, create your own MIDI sequences, backing tracks or songs using your favorite MIDI-USB keyboard.

The module uses a PIC 24 bit microprocessor to convert the midi messages from the keyboard or PC into digital codes which are then converted into gate and control voltages for 4 voices with precision DACs. These are buffered with precision op amps providing precise tracking over three octaves and to within 0.01V over 5 octaves.

The following MIDI-USB Keyboards are supported, others may work also.

• Arturia MiniLab MKII
• Arturia MiniBrute
• MidiPlus AKM 320
• M-Audio Keystation 49
• M-Audio Keystation 61
• WORLDE Panda MINI 25-Key Ultra-Portable USB MIDI Keyboard

Comprehensive documentation, parts lists and firmware are provided in the documentation link for building, testing and using the module.

Arturia addendum to user guide (Courtesy of Erik Moe, module builder and user):

Hold down the SHIFT key and turn ENCODER 1 counter clockwise a couple of rotations in order to set the master volume to 0. Once the master volume is set to zero, press the OCT (-) button 5 times and then Midi-CV-8 will be in command mode.