Partymaker: Accordion Synthesizer

This project is an electronic add-on for various types of acoustic accordions that brings the capabilities of a digital synthesizer to them. Unlike conventional digital accordions, it preserves the authentic feel and sound of the acoustic instrument, ensuring that musicians can effortlessly switch between classical and digital sounds. Sometimes it called a "MIDI system". Its main idea is the fusion of traditional acoustic and modern synthesizer worlds.

This system allows to keep an original accordion appearance as authentic as possible, even with built-in electronics, but this is optional though, as in some cases a synthesizer-like look may be specifically required. See the example accordion with the system installed on the picture below, only some knobs and the screen on the top are visible:

The principle is simple: each valve on the instrument has a sensor that indicates whether it's open or closed. The system continuously monitors the status of the valves, interpreting which keys are being pressed and seamlessly translating them into musical output.

Below is an example of how magnets are installed against the sensors.

The system integrates a pressure sensor inside the bellows that ensures the behavior of the accordion's bellows remains true to its acoustic counterpart. This means that when the accordion is played electronically, the bellows respond as they would acoustically, adding an extra layer of authenticity to the performance.

Features

• The system is self-contained, meaning it works without any external interfaces or boxes.
• Adjustable bellows pressure response.
• Rhythm machine and auto-accompaniment with many styles built-in, no external boxes, interfaces or modules required.
• A simple audio mixer for backing tracks built-in, no external boxes required. Connect your phone with backing track and play over it. Bluetooth input as an option.
• Customizable effects like echo, chorus, delay and distortion.
• Pitch bend and vibrato controllable via a joystick.
• Drums are automatically added to the ensemble when a musician presses the bass or chord keys.
• Rechargeable battery, 8 hours of operation on a single charge.
• An optional wireless audio transmitter.
• An optional microphone set with digital signal processing that is seamlessly integrated into the instrument to capture acoustic sounds of an instrument.

External interfaces

• USB device (MIDI class). Can be used with any computer, no drivers needed. Tested on Mac, Linux, Windows.
• MIDI output.
• Sustain pedal input.
• Two sensor boards, one for each half of the instrument, totalling max about 220 buttons.
• A control keyboard.
• A power-on button.
• Optional incremental encoders with software assignable action.
• A stereo output for speakers or headphones.
• Stereo inputs mixed to the output.
• Connectors for a digital microphone system (description is coming soon...)
• Analog joystick.

Why modify a classic accordion

• Go digital and leverage your skills with the same feel and response of an acoustic accordion. The same wooden body and weight. The same feel and force on the keyboards. Basically, you just use your skills and don't have to relearn for a new type of instrument, just use one you already know well.
• It is possible to keep the appearance of an accordion. The only visible part of the system will be a small OLED screen on the top of an instrument.
• Some instruments in the national free-reed aerophone family have no commercial digital alternatives, so the only way to go digital is to install such a system. These instruments are harmonicas, concertinas and bandoneons.
• The system has auto-accompaniment built-in, without any external boxes, interfaces or modules. No such feature is possible in any acoustic accordion.

What's inside

The system contains several modules:

• The mainboard with an embedded processor. Currently I have two versions: the one with external sound synthesizer module and the one with built-in synth (see picture below).

• The sound synthesizer board if external relative to the mainboard.
• The sensor boards containing valve magnetic or optical sensors. Normally there is a single board for each half of an instrument, but some instruments require more in some special cases. Sensor boards are uniquely designed for every type of accordion because of mechanical differences. Sensors layout is customizable via software for each type of instrument.
• Front connectors panel. Optional as connectors may be installed stand-alone.
• Control keyboard for voice switching and system setup (shown below). Normally installed behind the right keyboard and controlled with the thumb.

• OLED display with graphical user interface. The menu language is customizable. Shown below.

The main board, the synthesizer are installed inside the instrument, sometimes directly on the reed boxes, and connected together. This is one of the prototypes showing how it looks like:

The biggest and the most time-consuming part is installing sensor boards with counterpart magnets or LEDs.

Once all components are connected, the sensors layouts and synthesizer presets are to be configured via USB.

What to do with the instrument acoustic voices

If you play electronically, you will still hear acoustic instrument voices because you still use instrument bellows. There are several options to avoid hearing the acoustic voices.

• Remove acoustic reed boxes completely to make an instrument fully electronic. This is pretty simple as resonators are normally mounted with a couple of screws/clamp. This is what I made in my own instrument. It's now extremely lightweight, only 6 kilos. As an experimental feature, I have added class D amplifier with 15W speakers which required to redesign a standard power path schematics. As a drawback, the instrument lost it's very classic original appearance.
• Disable electronic bellows response completely and play like a piano. I used this option in one on my very first prototypes.
• Increase electonic bellows response sensitivity, so acoustic responce will be more quiet.
• Increase output volume so electronic sound will be louder.
• (the best) Some professional instruments (Weltmeister, Scandalli, Mengascini) have an option to switch off any acoustic response. That is, it is always better to initially select a musical instrument specifically with subsequent modification in mind.

Some demos

• Vladimir Butusov, a musician and friend of mine, presenting his button accordion with Partymaker system installed (English captions available):

• Sergey Antonovich (it's me actually :)) performing some solos on the modified Tula BN-51 button accordion:

• Vladimir Butusov's stage performance with the use an accordion with Partymaker Synth (timecode 2:18):