1 / 37 How to build a mobile soundsystem [email protected] - http://oscillating.space/ ● A short overview on the history of soundsystems ● Motivation for free open air partys ● Components of a soundsystem ● Power supply ● Amplifiers ● Speakers ● Additional stuff ● Example cost calculations ● Workshop: Build a soundsystem 

2 / 37 A short overview on the history of soundsystems ● Beginning in the 50s in jamaica – Disko on wheels – Reggae, Jazz, Blues ● Since mid 70s in northamerica with Hiphop&Disko – Ghettoblaster ● (Illegal) Rave culture in europe since end of 80s – UK – Germany ● Freetek, Teknivals get massive police repression ● Nice Arte Docu: Sound System - Tontons du sound 

3 / 37 Motivation for free open air partys today ● Its nicer to party outside in the sun ● Overcrowded clubs in Berlin ● Nice to organise your own partys ● Less opportunitys to play in clubs ● Nonviolent protest ● Its fun fun fun fun 

4 / 37 Components of a soundsystem Power supply Amplifier Speakers DJ Equipment Yeah! 

5 / 37 Maximise the Yeah! factor ● The only formula for today... – The longer the music the better – The louder the music the better – The less money the better 

6 / 37 Power supply - Generator ● Advantages – Lots of power to use – Standard power plugs ● Disadvantages – Burning old dinosaur shit to get power - WTF?! – Smelly and leaking liquids – Forbidden in parks - Ordnungsamt can sue you instantly – Heavy (but you can also get small ones) 

7 / 37 Power supply - Batteries ● Standard liquid car batteries – Acid liquids can leak – Bad stuff – Advantage ● Cheap – Disadvantage ● If not standing vertically it can leak acid ● Acid is unhealthy and environmental hazard ● Need to refill with liquids from time to time 

8 / 37 Power supply - Batteries ● Solid material Batteries – Gel- or AGM-Batteries – Sealed to prevent leaking – Advantages ● No leaking ● Without maintainance (no refill) ● Resistance against deep discharge – Disadvantages ● Expensive (approximately 2x as standard) 

9 / 37 Power supply - Batteries ● How much Power is in a Battery? – Amount of power in Ampere Hours (Ah) – Discharge curve – State of charge readable by Voltage of Battery – Discharge until 11.8V is ok – Below 11.8 the battery gets destroyed slowely – Destroyed battery irreparable – Only 70% of capacity usable 

10 / 37 Power supply – Solar Power ● Advantages – Recharge batteries – Sustainable energy ● Disadvantages – Only usable in the sun – Additional cost (Solarpanels + Inverter) – Not good usable without batteries ● Cost – Depends on the power but > 150 € 

11 / 37 Power supply – By Bike ● 30W – 100W per Person ● Advantages – Generate power independently from the weather – Generate power from Beer/Food (Healthy!) ● Disadvantages – Buying is expensive: www.oekotrainer.de – DIY 

12 / 37 Power supply - Buying tips ● For mobile music batteries are the best ● Additional cost for Solar or generator is too high ● Buy only new batteries ● Solid material batteries because they are leakfree ● The bigger the batteries the smaller is the price for the power ( € / Ah ) ● Use good chargers for AGM-Batteries (highvoltage) ● Bicycle Generators are nice but complicated 

13 / 37 Components of a soundsystem Power supply Amplifier Speakers DJ Equipment Yeah! 

14 / 37 Amplifiers ● Most important technical spec is the efficiency – The more efficient, the less power gets wasted to heat – Heat needs to get cooled with even more energy – If amplifier gets too hot it turns off / gets destroyed – Good amplifiers have more than 80% efficiency – Class D / digital amplifiers have a good efficiency – Old analgue Class A / B amps got ~60% 

15 / 37 Amplifiers ● Possible amplifier setups for a soundsystem – Class D / Digital car amp – Step-Up-Converter + Class D amp board – 230V-inverter + normal 230V PA-equipment 

16 / 37 Amplifiers ● Amplifier power rating in Watts – The only right rating is Watts RMS / Sinus! – Watt PMPO: fake power rating ● Also called „Pure Mystic Power Output“ ● Its the power you can put on the speaker before it catches fire – Ohm load of the rating is also important: ● Example: – Power rating: 50W RMS @ 4 Ohm – Matches: 25W RMS @ 8 Ohm 

17 / 37 Amplifiers ● Cooling – Car amps not build for heavy usage longer than 2h – Additional heatsink or fan is needed – Use thermal paste for better thermal connection – Use a huge area to connect the heatsink to the amplifier – Use a efficient 12V fan (high airflow / watt) 

18 / 37 Amplifiers - Buying tips ● Get a car amp ● Get a Digital amp with high efficiency (>80%) ● Get a used amp from ebay / Kleinanzeigen to save money ● No high power rating necessary for each output – 20W / 8Ohm for a small soundsystem – 100W / 8Ohm is enough for a big soundsystem ● Analogue amps only good for small soundsystems because they generate too much heat 

19 / 37 Components of a soundsystem Power supply Amplifier Speakers DJ Equipment Yeah! 

20 / 37 Speakers - Setups ● Most important part in the soundsystem ● Different Setups possible – Classic 2.0: ● Two fullrange speakers ● One amp with two outputs – Additional Subwoofer 2.1: ● Two speakers as mid-/high-Speakers ● One subwoofer as low-Speaker / bass ● Crossover needed to split the frequencys ● Two separate amps necessary 

21 / 37 Speakers - Sensitivity ● The watt rating of speakers is NOT equivalent to the loudness of a speaker ● Sensitivity / „Wirkungsgrad“ is the important value – Given as dB/w/m in the technical specs – It says how loud is a speaker in a distance of 1 meter if you put 1W RMS of power from an amp to the speaker ● The higher the sensivity, the longer the battery lasts at the party! 

22 / 37 Speakers - Sensitivity ● How much watts needed ? – Loudness measured in dB – „Discoloudness“ = 100dB – Berghain = approx. 110dB – Speaker with 85 dB/W/m ● 100dB: 32 W RMS ● 110dB: 300 W RMS – Speaker with 94dB/W/m ● 100dB: only 4 W RMS! ● 110dB: 50 W RMS Loudness examples with Distance Loud ness dB Jet airplane in 30 m 140 Pain threshold 130 Discomfort threshold 120 Chainsaw @ 1 meter dist, 110 Disco @ 1 m infront speaker 100 Dieselmotor @ 10 m dist. 90 At a busy street 5 m dist. 80 Vacuum @ 1 m distance 70 Normal talking @ 1 m dist. 60 Normal flat quiet 50 In a quiet library 40 Quiet sleepingroom by night 30 

23 / 37 Speakers - Buying tips ● Buy speakers by efficiency ● Speakers should have > 92 dB/W/m efficiency ● Match Watt RMS to power rating of the amp ● Consider the ohms of the speaker (see amps) ● Used speakers are ok to buy and cheap ● DIY possible and very cheap – Speaker is basically just a wooden box – Wide-range speakers play bass/mids/highs – Lots of plans in the internet (see links) 

24 / 37 Components of a soundsystem Power supply Amplifier Speakers DJ Equipment Yeah! 

25 / 37 Additional stuf ● Fuses are really important: – Choose by max current – 100W => 16A fuse – 200W => 30A fuse – 300W => 50A fuse ● Cables: Cable cross section by power rating – 100W => 0,75mm² – 200W => 1,5mm² – 300W => 3mm² – 400W => 5mm² 

26 / 37 Additional stuf ● Voltage display – To prevent deep discharge of the battery – Dont pay more than 5€ – Reminder: After 11.8V change the battery to prevent harming the battery ● Equalizer for the soundsystem – Adjust the bass to avoid police – Adjust the highs 

27 / 37 Additional stuf ● Inverter: generate 230V AC from 12V DC – Different types of inverters: ● Rectangle ● Sinus – Sinus for audioequipment – Pay attention to efficiency: higher than 80% ! – Advantage: Use regular 230V equipment – Disadvantage: Unnecessary voltage conversion which costs power and therefor hours of music – Needs to get cooled ! 

28 / 37 Additional stuf ● The horse: Transporter – Trolley – Sack truck – Shopping cart – Hand cart – Wheelchairs – Baby carriages – Wheelbarrow – Bicycle – ??? 

29 / 37 Pics 

30 / 37 Pics 

31 / 37 Additional stuff ● Lights – Use LEDs because they need way less power – Battery powered LED light strings ● Laptops – Use laptop battery – If battery is over, remove battery and use only the laptop power supply (very inefficient to charge laptop battery from another battery) – MacBook Trick: Block middle pin of charger with ducktape to prevent loading of battery ● DJ Mixer: use 12V Mixer (eg. Xone 22) 

32 / 37 Example cost calculation - Small soundsystem Type Name Spec Price Battery QUATPOWER LB12-12 AGM 12V / 12Ah 20 Amplifier Kinter MA 700 2 x 13W / 8 Ohm 15 Speaker DIY Visaton BG 20 40W / 8 Ohm / 92dB/w/m 25 Speaker Wood + small parts 10 Voltage display … 5 Horse Sack truck 24 Additional stuff Cables, Fuses and shipping 15 Sum 114 Resulting loudness 102dB @ 13W : Lasts 7h 108dB @ 2x13W : Lasts 3,5h Yeah! factor 82 

33 / 37 Example cost calculation - Bigger soundsystem 

34 / 37 Example cost calculation - Bigger soundsystem Type Name Spec Price Battery MaxBatt AGM Batterie 12V / 110Ah 130 Amplifier Ampire MBM 100.4 2G (used) 2 x 200W / 4 Ohm / 84% Efficiency 125 Speaker 2 x Thomann PA 302 (used) 300W / 8 Ohm / 96dB/w/m 150 Speakerstands 20 Equalizer 35 Inverter Arebos Sinus Inverter 300W / >80% Efficiency 30 Horse Hand carts 60 Additional stuff Cables, Fuses and stuff 45 Sum 595 Resulting loudness 116dB @ 2x30W : Lasts 13h Yeah! factor 73 

35 / 37 Conclusion ● Efficiency is the most important spec in a mobile soundsystem ● Use leakfree batteries ● Dont do deep discharge of the batteries ● Important to look after the efficiency of the amp that there is less need to cool it ● Use crazy good efficient speakers to get the loud music for a little of power and for a long time! 

36 / 37 Linklist [email protected] ● Bicyclegenerator: http://www.magnificentrevolution.org/diy/single-bike-generator/ ● Amps: – Efficiency of a lot of amps http://amp-performance.de – Overview small amps: http://www.hifi-forum.de/viewthread-118-2855.html ● Speakers – Pages with plans: Hififorum, Jobst Audio – Plan for Visaton BG20 Partyboombox: http://www.lautsprecher-berlin.de/partybox.html ● Shops for soundsystem stuff: – Speakers: Geizhals.de – under „Lautsprecher“ filter with „Empfindlichkeit ab 92dB“ – Pollin.de & Reichelt.de for electrical parts, batteries and speakers ● Inspirations for soundsystemconstruction: – https://www.hedonist-international.org/?q=de/node/414 – http://www.hifi-forum.de/viewthread-118-1591.html 

37 / 37