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12/24v solar powered PA system for Burning Man

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natarius View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote natarius Quote  Post ReplyReply Direct Link To This Post Topic: 12/24v solar powered PA system for Burning Man
    Posted: 06 September 2017 at 2:08am
Hi,
I am looking into building a modular power efficient PA system that can be run 20h/d via solar.

Right now we use a 2KW Yamaha system off a generator...but the generator broke this year and we wanted to stop burning fossil fuels anyways...so here we go :)

For starters I just want to replace the existing system...maybe add a sub to it.

I found this tutorial on http://www.instructables.com/id/Battery-Powered-Mobile-Party--Systems/ - instructables which looks pretty straight forward...they claim its possible to build a system thats 2-3 times more efficient then a off the shelf setup.

I don't want to make this more complicated then I have to...but down to also build everything from scratch if I have to.

Any thoughts?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote monop0d Quote  Post ReplyReply Direct Link To This Post Posted: 06 September 2017 at 9:47am
Hi there,

There's a million answer to this, but the following guidelines will hopefully get you a long way

You're best off running with passive speakers, to give you the option of selecting the amp yourself. At the same time, you'll be able to run your whole system on a much lower voltage instead of 220V.

For speakers the key factor is sensitivity. You want to use as little energy as possible to play as loud as possible. Aim for atleast 95 dB 1w/1m. Besides this you can select on whatever parameters suit you the best, e.g. weight, size, frequency range, etc.

One note here, is that it requires a huge amount of energy to play loud when you start getting below 80-70 Hz. Unless you really want to scale up, you're best off not trying to reach those low 40's

For amplifier there's pretty much only one route and that is Class-D (Digital amps, in some cases called Class-T). Many car amplifiers use Class-D, a popular one in Europe is the Pioneer GM-D8604. If you don't need all the settings and want to work with DC-DC converteres yourself, Sure Electronics makes some quite cool boards as well. 

In my own system used for a similar usecase (Roskilde Festival in Denmark), I'm running with the Pioneer and a Bassface DB1.2 to power to PA tops  and two Cubo15 subs

Battery wise your best option is to run with Lithium-Iron Phophate (LiFePO4) however, these are also quite expensive. Go for 12 or 24V dependent on your choice of amplifier. Your next best option would be to run with some sort of deepcycle lead battery. These go under many different names (gel, glassfiber, etc.) I'd aim for having a battery bank of around 2-300 AH in lead acid or perhaps 100AH in LiFePO4.

Solar cell wise I'd go for monocrystaline for efficiency. If you're expecting more grey weather and have the shells shaded every now and then, I'd suggest going with CIGS (thin film) solar cells. I'm running 2 pcs. 110W CIGS for my system, and it lasts a full 7 days with about 5-600 AH battery capacity. Keep in mind that Denmark got quite shitty weather, but also lots of day (only dark from 23 till 04 in Summer)
You'll also need a solar controller to take care of solar cells, batteries and amplifiers.

Start reading up on these and feel free to come back with any more questions :)
SOUNDBOKS representative and dedicated to Roskilde Festival, 12V systems and aesthetics
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Post Options Post Options   Thanks (0) Thanks(0)   Quote davey t Quote  Post ReplyReply Direct Link To This Post Posted: 06 September 2017 at 9:53am
Get some good quality AGM batteries (probably need 6 or 8 110aH ones for 2k system running 20hr)
3 good quality class D car amps (two 1k mono for bass, one 4/5ch for tops). Vibe/Alpine etc. 
MiniDSP for crossover/limiter or use an inverter and 240V crossover of your choice if you have big enough batteries. 
For running decks/monitors/frontline you'll probably need an inverter anyways - there are some 12DC mixers/CDj/decks though

In reality, you're not going to power your system from solar unless it's a really nice day and you spend a fortune on panels. Better to spend more money on batteries and charge them slowly via solar before the gig. 




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Phil B View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil B Quote  Post ReplyReply Direct Link To This Post Posted: 06 September 2017 at 1:17pm
Cough ... errr ... you could just borrow mine .... ( with some nice new Li-Po's you'll get 20 hr days )


But seriously though it's possible.

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Solar Sound System Shennanigans..http://diyhifi.biz/
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Post Options Post Options   Thanks (0) Thanks(0)   Quote valve head777 Quote  Post ReplyReply Direct Link To This Post Posted: 06 September 2017 at 4:58pm
how about a mixture of both technology's? A small pure sine inverter for running decks mixer and xover and DC run amplifiers. Big inverter's pull efficiency down. As said, speaker sensitivity is important. If you are using banks of batteries, you are not stuck on 12v, 3 in series gives 36v so good for DC amplifiers. Lots of info from other threads on amp boards.
I would say that in undersized solar array may not do your batteries much good when they are run really low, because at bulk charging stage they really demand a high current to pull the ions through the plates and prevent sulfation. Hope this helps...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote natarius Quote  Post ReplyReply Direct Link To This Post Posted: 07 September 2017 at 1:31am
Thanks for the replies guys :)

Burning Man goes on for about 10 days...so preloading the batteries won't do...we have to recharge them everyday. All our lights are solar powered though...so we have some experience.

Since it's in the middle of the desert we are getting 88watts out of 100watt panels for about 5h a day.

Thanks for the 36v tipp...the best voltage for amps was one of the questions I had in mind already. I would try to run as much of the system at 12v (which I have for lights anyways) or 36v then. And only invert when I absolutely have to, like for for the DJ decks.

From reading around it seems best to have a class T amp for every driver since that's the most efficient use of power (because bass drivers are less effiecent than mid or highs). I that case I would built a set of active speakers I guess. Any advice on that?

Would you recommend building speakers from scratch or just retrofitting off the shelf ones?



Edited by natarius - 07 September 2017 at 1:32am
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markie View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote markie Quote  Post ReplyReply Direct Link To This Post Posted: 07 September 2017 at 1:21pm
Just a thought, how about adding a couple of bicycle generators to the system. I'm sure the eco frieldly festival goers would be happy to contribute some pedal power to maintaining an eco friendly sound system.

I read somewhere that a bike generator can produce up to 100 watts.

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If it's got wheels or tits it's gonna cost a fortune
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natarius View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote natarius Quote  Post ReplyReply Direct Link To This Post Posted: 07 September 2017 at 4:07pm
Hahaha...actually not a bad idea :)

100w per hour or?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote valve head777 Quote  Post ReplyReply Direct Link To This Post Posted: 07 September 2017 at 5:12pm
Not a bad idea..... Look up 'rinky Dink soundsystem'
This was originally built and used for the road protests in the 90's. Used a back wheel with neo magnets and home made coils.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote valve head777 Quote  Post ReplyReply Direct Link To This Post Posted: 07 September 2017 at 5:44pm
Really kinda love the subversion of rinky dink. Need lots more of that in these corporate days. Power from the people!

100 Watts is a sustainable power output from a human (fit) body, 350 in bursts. Drop the baseline 'N get peddlin!!
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studio45 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2017 at 7:31pm
I've been experimenting with a friction drive system, using a 250 watt internally geared hub motor off a Decathlon BeBike, mounted off the seat post on a bracket. It has the advantage that it works with any bike, as long as it can be put up on a stand of some sort and the pannier rack doesn't get in the way. Downsides are some loss of efficiency in the drive and some loss of rubber from the tyre Confused But it is good for about 7 amps at 24v, in bottom gear with not much effort. I have it connected to a 50F bank of supercaps and a set of converters to give me 17v out at 15A max, which I can use to charge my Li-Ions or power the rig directly (about 5 minutes play time on the caps alone!)
Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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Post Options Post Options   Thanks (0) Thanks(0)   Quote valve head777 Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2017 at 10:36pm
NIce idea...Clap
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