ANDERS AABOEENGINEERING PORTFOLIO
All projects
P15 / Personal build2015–present

Solar-powered mobile PA system.

A progression of self-built sound systems, from a portable Boominator and Halfinator to two CUBO 15 subwoofers and a complete solar-powered mobile PA with amplification, DSP, battery power and lighting, in use at festivals since 2017.

SketchUpCabinet fabricationAudio electronicsDSPBattery systemsSolar charging220 V inverterArduino
A festival crowd at night in green light, with the mobile PA playing and string lights overhead.
The mobile PA playing for a festival crowd at night.

Sound systems built

4 builds

A Boominator, a Halfinator, two CUBO 15 subwoofers and the complete mobile PA, from 2015 to 2017.

In use at festivals

Since 2017

The core sound system is unchanged, while power outlets, lighting and DJ equipment have been upgraded over the years.

The goal

Long before the university projects, sound systems were the first engineering builds: each one bigger and more complete than the last. What started as a portable battery speaker in 2015 grew into a solar-powered mobile PA that has been in use at festivals since 2017.

The PA as a DJ booth with a painted Spacecamp sign, and a DJ playing behind it.

The PA as the DJ booth of a festival camp, 2022.

My involvement

Designed, built and wired all four systems: cabinet fabrication from published plans, driver and amplifier installation, battery and solar power systems, the SketchUp design of the mobile PA, and its upgrades over the years.

2015: Boominator

The first build was a Boominator, a portable twin speaker built from published plans: plywood cabinets with separate chambers, drivers and tweeters, a lead-acid battery and a car amplifier, all in one enclosure that could be carried to a party.

A workbench with cut plywood panels, drivers in their boxes, glue and tools laid out for the Boominator build.

The plywood panels and parts laid out for the build.

The Boominator cabinets clamped together while the glue sets, with the drivers mounted in their chambers.

Gluing and clamping the cabinets.

Gluing the inside of the open Boominator cabinet, with the drivers wired in their chambers.

Sealing and wiring the Boominator cabinet.

The finished black Boominator, with two drivers behind grilles, tweeters and a control panel in the middle.

The finished Boominator.

2016: Two CUBO 15 subwoofers

For more bass, two CUBO 15 subwoofers were built from published plans. The cabinet folds the air path inside the box, so a 15-inch driver gives deep bass from a compact enclosure. The panels were cut, assembled and sealed, and the cabinets finished with a hard-wearing black coating and corner protectors.

A CUBO 15 cabinet under construction, with the internal panels that fold the air path and the opening for the driver.

The folded air path inside a CUBO 15 cabinet during assembly.

A finished black CUBO 15 subwoofer with green corner protectors.

A finished CUBO 15 subwoofer.

To drive the CUBOs, a large Pioneer amplifier was added. The Boominator was then redesigned so that its small internal amplifier could be bypassed: plugging in a speaker cable with an 8-pole connector disconnects the internal amplifier and lets the external Pioneer amplifier drive the speakers instead. There are no switches; the connector itself does the switching mechanically.

A large Pioneer amplifier mounted in a separate box with the battery, with its power and speaker wiring.

The large Pioneer amplifier, mounted in a separate battery and amplifier box that feeds the CUBOs and the Boominator.

The Boominator opened on a workbench, with its battery and electronics module, next to the Pioneer amplifier and a laptop.

The Boominator’s electronics during the redesign, next to the external Pioneer amplifier.

The first finished CUBO 15 subwoofer and the Boominator standing side by side on a lawn.

The first finished CUBO 15 and the Boominator playing together.

2016: Halfinator

The Halfinator is a half-size Boominator: a single portable cabinet with the same idea in a smaller package, with its own battery, amplifier board, drivers and horn tweeters. It was built for my younger brother.

The Halfinator cabinet under construction, with a driver and horn tweeter mounted in the plywood.

The Halfinator during assembly.

The finished black Halfinator standing on a lawn, with a green grille and horn.

The finished Halfinator.

2017: The mobile PA

The final build combined everything into one mobile PA: the two CUBO 15 subwoofers, store-bought PA top speakers, new amplifiers with DSP tuning, and a DJ mixer, built into a wheeled DJ booth on a trailer. The external-amplifier setup carried over, and from time to time the Boominator was connected through its 8-pole connector as an extra top speaker.

Design

The booth was designed in SketchUp around the subwoofers and top speakers, with space for the DJ in the middle and the electronics below.

SketchUp front view of the PA booth on wheels, with top speakers on raised towers and two subwoofer openings at the bottom.

Front view of the SketchUp design.

SketchUp 3D view of the PA booth on wheels, with the speaker towers and the DJ space in the middle.

3D view of the SketchUp design.

Build and power

The booth was built on a trailer chassis. The power system combines batteries, solar charging and an inverter for 220 V AC, so the PA runs off-grid. Arduino-based control drives LEDs synchronised to the music.

The trailer chassis on a lawn with its railing, while the PA is being built on it.

Building the PA on the trailer chassis.

An LED strip glowing red on a desk, connected to a soldered green control PCB, with a battery, multimeter and laptop.

Testing the LED strip and the control PCB after soldering.

The PA structure on its trailer in a garden, painted black with the top speakers in place, before any artwork.

The finished woodwork, painted black, before any artwork.

The power panel of the PA, with a charge controller display, fuses, bus bars and switches.

The power panel during the build.

Power outlets on the PA at a festival, with USB chargers and 220 V sockets in use.

Power interfaces on the PA, with USB charging and 220 V outlets.

Since 2017

The core sound system has stayed the same since 2017, while the rest has been upgraded for life at festivals: phone chargers and 220 V outlets for things like air mattress pumps, new lighting equipment and light controllers, and different DJ mixers over the years. The booth has also been repainted for new looks.

The DSP was tuned outdoors with field recordings. An outdoor PA has nothing for the sound to reflect from, and on battery power the lowest frequencies are the most expensive, since they take the most power to drive in the subwoofers. The tuning therefore cuts as much of the deepest sub-bass as possible without hurting the sound quality, and gives more weight to the punchier upper bass, which keeps the feel of the music within the battery budget.

The black PA booth on a lawn in daylight, with a person behind it.

Field recordings and DSP tuning for the best outdoor sound.

The black PA booth painted 'Koen Marla' at a festival campsite at sunset, with a DJ behind it.

The PA at a festival campsite at sunset.

The PA booth repainted yellow with 'Mer' Mælk' on the front, in daylight.

The PA repainted yellow.

The PA painted with a Spacecamp sign at a festival campsite in daylight, with a solar panel lying in front of it.

The PA at a festival campsite, with its solar panel in front.

IN USE

The crowd and the party in full swing, 2017.
A dense crowd dancing in coloured light in front of the PA at night.
The crowd in front of the PA at night.
The PA lit up at night under string lights, with people gathered around it.
The PA set up under the string lights.
A crowd at night in blue light with the PA lights in the distance.
A night set in blue light.
The PA booth repainted yellow with 'Mer' Mælk' on the front, at dusk with green lights on.
The yellow PA at dusk with the lights on.
The black PA painted 'Koen Marla' at a festival campsite, with DJs behind it and a cow-painted cart beside it.
The PA at a festival campsite, with a cow-painted cart alongside.

KEEP EXPLORING

Another side of the work.

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