Rolling Lion Hi-Fi @ Oranienstr. - 08_2022As you may have noticed, we’re quite the fans of dub and soundsystem culture at A Bass Odyssey, and it was only a matter of time before we started building our own sound! During the first C-19 lockdown in 2020, I decided to begin with a battery powered, 3-way system for home/studio use, which could also be mounted on a cargo bike for small mobile/open air sessions. Since then I’ve spent quite a bit of time optimising the system, and as there have been a number of questions about the sound over the past 2+ years, I decided to create a walkthrough of the process, including components used and updates made to the sound during that time. So without further ado – please give a warm welcome to the “Rolling Lion Hi-Fi“!

I’d been thinking about building my own sound system for quite some time, but mainly due to storage constraints and often moving house and studio or travelling for longer periods of time, it was never really a practical endeavour! Upon returning to Berlin in March 2020 from some winter travels, and learning that the future of our next events was up in the air due to C-19, I decided to use the “lockdown” time to work on some other projects. With a new base of operations on the outskirts of Berlin and a full wood workshop, there was nothing left to keep me from starting on this one!

Why a 12 volt sound system?

I decided to start this next chapter of the odyssey with a “mobile” version of a 3-way sound system – with 3 separate sections for low, mid and high frequencies – which could also be used at home / in the studio, and eventually mounted to a cargo bike for the odd open air session here and there. The system is fully powered by a 12 volt “leisure battery” (Varta LA95), and after the first test sessions in the area, it seems to last for at least 8 hours at a decent volume!

Update June 2021: After a few sessions I’m thinking the battery capacity may be a good deal greater than initially assumed! Nonetheless I want to upgrade the battery to a 100ah LiFePo4, which would basically double the potential playtime (as my current battery should only be discharged to 50%), while cutting the weight by 50-70%!

Did you use plans for the design?

IMG_20200517_130500I began by scouring the internet for different plans (“Speakerplans Forum” and “12v Sound Systems” Facebook group have both been great resources!), and eventually settled on the Cubo15 design – a 62cm cube powered by a 15″ driver – which would amplify the lower frequencies between 40-100 hertz. After asking a lot of colleagues about other recommended designs for the mid / top sections (and receiving various responses from everyone I asked!), I decided to just start on the Cubo, and then build the other sections according to my own vision of how I wanted the sound to look! I could have spent months researching different aspects of sound design, frequency response and whatnot, but as a practical learner, I decided to just begin the project. After all, sound systems are a constant learning curve, and there will be plenty of time to learn about the various aspects and make any necessary adjustments to the design!

How did you construct the rest of the sound system?

IMG_20200603_111545After I finished building the Cubo15 – using 15mm birch ply, I installed the Eighteensound 15ND930 15″ driver I chose to provide the low-range frequencies. Although the original design calls for 18mm birch ply, I decided to use 15mm to cut down on some of the weight, and used the same wood for all cabinets. Next I built a custom designed mid-cabinet (62*30*30cm) which houses 2x 8″ drivers (Eighteensound 8NMB420), providing the mid-range frequencies between 100 – 2,000 hertz. Then came the top-cabinet (62*20*20cm), which houses 2x 1″ compression drivers (Eighteensound HD1050) attached to “horn flares” (Eighteensound XT120), thus providing more balanced sound coverage. Once everything was built, all drivers and speaker ports installed, all connections glued and screwed, it was time to give the wood a nice finish. I chose an all-natural wood glaze (Deutsch: Holzlasur), with an Oregon Pine tone, which gave the wood a slightly darker, orange hue.

Afterwards I built a simple cabinet to hold all of the various components and cables, battery, amplifier, DSP and capacitor, and also added some hexagonal speaker grilles and protective speaker foam to avoid any dust or damage to the drivers.

Update Summer 2022: Following a minor incident involving an unforeseen obstacle in the road, I managed to tip the loaded bike, thus damaging one of the tweeters on the way to a session. The other tweeter was still working, so I decided to create a new horn using the one remaining tweeter (see picture at top of page), which so far seems to be powerful enough to keep up with the rest of the system.

Which other components did you use?

IMG_20200604_173305The music signal is sent from the source (for now a phone or laptop) into the input of a t.Racks 4×4 mini DSP (digital signal processor), which splits the input (music) signal into the appropriate frequency bands for the respective drivers (app. 40-100 hertz to the subwoofer, 100-2,000 hertz to the mids and 2,000-20,000 hertz to the tops). Using their proprietary software, you can choose flexible cut-off frequencies and crossover points, adjust delay times between and equalize the various outputs.. quite a powerful bit of kit! The 4 outputs of the DSP are then connected to the 4 inputs of a 4-channel, 1200w car amplifier (Pioneer GM-D8704), sending the respective frequency bands to the respective channels on the amp, and further on to the drivers. The subwoofer is wired in “mono bridge” mode on Channel A (left and right), and the mids and tops each get their own separate power and signal from Channel B (mids left; tops right). Between the 95ah AGM gel battery (Varta LA95) and the amplifier there is an 80A fuse to help prevent any power surges, as well as a capacitor (Crunch CR-1000 Power Cap), which is used to store power and keep a steady flow to the amplifier, preventing any potential power shortages.

Update March 2021: In the future I’ll think about a different amp, as the Pioneer GM-D8704 falls slightly short for my 3-way system. With the sub taking up 2 of the 4 channels, I basically had both 8″ drivers wired together to the 3rd channel and both 1″ drivers on the 4th channel. For the past months of home use I’ve had the sub on it’s own (230v) 1200w amplifier, with the other 4 drivers each getting their own channel on the GM-D8704. After researching a bit I found Pioneer makes another amp with 2,400w, and a dedicated sub output. So basically it’s the same as my current amp setup, but with 2 amps in 1! 

How does it sound?


The first sound check was surprisingly good for having just wired everything up and making some intuitive adjustments in the DSP software! At first we tested the sound in the workshop, driving the levels up to a point where the mid and top cabinets began to vibrate off of the subwoofer! After fastening a tension belt around the stack (which is about 110cm tall), we continued making some adjustments in the software, until we found a balance we were happy with. On the next day we rolled the stack into the garden, and were surprised to realize the bass was even stronger / warmer outdoors (using the same settings)! There’s still a lot to be done, but we’ll get to everything in due time.

What’s next?

IMG_20210315_215309During another “lockdown” in winter 2021, I created the “Rolling Lion Hi-Fi 2.0“, which has been sitting in the studio and providing some nice sound in stereo! After crafting 2 “mini-scoops” for the 8″ drivers, I started on some horns for the 1″ drivers, and gave them a nice finish after sanding everything down by hand. I’m really happy with the way they turned out! Also I’m looking into upgrading the system to run on solar, so it will be truly “stand-alone”. I’ll likely be getting 2 solar panels on loan, and will order some LiFePo4 batteries, which are way more efficient, long-lasting and lighter than the beast of a lead-acid battery I have now! Stay tuned to see what happens next ❤

Update: In June 2021 I took the sound out for a little ride – 50+km! – as part of the world’s largest bike demo called “Sternfahrt”. Riding from my home base in the southeast of Berlin, I head into Neukölln where I met up with a bunch of people and jumped on the Autobahn! From there we rode past Tempelhofer Feld and then north to Zoo and finally to Brandenburger Tor, where we chilled for a few hours in the park! 

New & Improved Music Box (a.k.a. “Control Tower 2.0”)

In late 2022 I decided to invest some more time and energy into the music playing aspect of the sound system, as up until now I had just been playing from an iPad someone had loaned me, with my siren and delay to add a bit more character. I had some 18v Dewalt (power tool) batteries, and began some research on how to power some devices off of those. It was actually quite easy, and just required a 20€ “bucket” converter to change the voltage from 18-12v. The converter also shows how much current is being drawn, and according to my calculations one battery should last about 5 hours (and I have 3 such batteries, so I will be able to keep a session going for quite a while!). I also found a mixer which would run on a 12v “barrel connector” – the same power plugs I had already installed for my DSP, siren and delay. I got the mixer (RCF F10 XR) used but in great condition, and began to build a wooden enclosure to house the iPad, mixer, FX, battery and converter. After some more bargain hunting I found a used iPad with ample storage which would run Pioneer’s WeDJ program in conjunction with a basic DJ controller (Pioneer DDJ-200). I did some more work on the enclosure with a router to make everything fit nice and snug, got a standard 5v power bank to power the controller & iPad, and added my Korg Monotron Delay to the box for some added flavour! Can’t wait to test out the new setup in a couple months!!

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Shout outs to Joe Redub & Darkwing Dub for the input, as well as everyone on the Speakerplans Forum and 12v Sound Systems group for supplying so much knowledge!

12v Sound System Schematics