Instructables
Whether its for a mobile bike party or a solar powered concert, a 12V or 24V sound system is the key.  I recently built several systems for mobile bike parties and this article has a pile of details.  You can also check my Easy Bike Party Sound System project if you want a simpler and smaller system and my Bike Party Sound Trailer for specific tips on a trailer design.  If you want to just purchase finished speakers built according to the principles of this guide, we sell them at MonkeyLectric.

This article covers:
  • A simple but efficient setup where you just pick the right parts and plug it together
  • A true Active 12V speaker - an ultra-efficient speaker with integrated 12V or 24V internal amp.
  • Choosing efficient speakers and amps
  • Choosing a battery
  • Weatherproofing and vibration proofing
The goal of this project is to achieve sound levels needed for off-grid dance parties while reducing weight and power use.  Compared to common setups, we achieved power reduction of 50-80% and weight reduction of 20-40% with equivalent sound output.

My friend Deep runs Flashdance, and we used his system as a reference point to compare our work against.  Deep has an amazing tricycle setup that lets him bring the party wherever he goes.  San Francisco has rather notorious hills though, so our goal was to see if we could cut the weight of his setup without sacrificing any of the sound.  A big key to cutting the weight is to see if we can use something much smaller than a car battery - and that means being more efficient about power use.

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This project is brought to you by MonkeyLectric and the Monkey Light bike light
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saltvand4 years ago
The TK2050 thaqt I have looks i little bit different. See it here: http://img411.imageshack.us/img411/4465/img4302r.jpg IS there a way I can increase the volume on my model?
IMG_4302.JPG

Did you ever find out a way to increase the sensitivity?

dan (author)  saltvand4 years ago
oh, the other solution is to use a powered mixer to boost the mp3 player signal before the amp. i'm using a Rolls MX51s which is about $50.
dan (author)  saltvand4 years ago
you have the 4-channel version. i think yours must have the pre-amp chips on the underside of that daughter-board. can you un-plug the daughter card and post a photo of the bottom side of it? (close up, use macro-mode on your camera).
ejones2628 days ago

I know nothing about this but I got a chuckle out of the estimated weight of a car battery when he estimated it to be 40-50 lbs. Wow!!! That's one mother of a car battery. A huge 24V truck battery....maybe, but a car....naw. The battery in my car weighs maybe 10 lbs. I have removed it several times and if it weighed 40-50 lbs. I would be on compensation now moaning about my sore back.

Bowtie4128 days ago

You can also get these very cheap at aliexpress

barrem0128 days ago

Forgive me if my questions are naive.
Why discard the crossover that is already in the speaker?
The links to your monoXover don't seem to work, can I still get it in either kit or per-assembled form?
Would this do as a replacement for your crossover?

http://www.parts-express.com/ec-27-2-way-bi-ampabl...

Is "bi-ampable crossover" the same as "pre-amp crossover"?

JeremyA228 days ago

This is a great instructable!

I wanted to add some info on the batteries: I recently installed new batteries on my RV and I did a lot of research and discovered lithium iron phosphate is a new chemistry that packs more amp hours into a smaller and lighter package that doesn't have the propensity to "blow up" when improperly charged like standard lithium-ion.

Take this battery for instance:

http://www.amazon.com/Phosphate-replaces-CF-12V4-5...

If you look around, there are several other brands out there that might be cheaper, I just picked the first one I saw on Amazon that was around 4-5 Ah.

It's 4.5 amp hours and weighs 1.45 lbs! Less than half the weight of an equally sized SLA battery. Lithium-iron-phsphate can also be discharged much more fully than lead-acid. A lead acid battery suffers permanent loss of life if it's discharged more than 50%. Lithium-iron-phosphate can be discharged down to 20% with no long term affects thousands of times. A gel lead acid battery can only be discharged down to 50% 200-300 times before the battery's life is pretty much gone.

So the 4.5 Ah Lithium-iron phosphate offers 3.5 "usable" Ah while the equivalent SLA rated at 4.5 Ah will only offer 2.25 usable Ah.

If you factor the weight the lithium battery offers about 2.5 usable Ah per pound while an SLA offers about 0.75 usable Ah per pound. If weight is an important factor, the lithium battery offers over 3x the usable power to weight ratio. meaning switching to Lithium-iron=phosphate would make your battery pack 2/3 lighter.

The price of the Lithium based battery is higher up front, but if you factor in that it can be re-charged over a thousand times compared to the 200-300 times of an SLA the long term cost if you actually use the battery very often is actually cheaper.

Just food for thought.

-Jeremy

ukushu1 month ago

If a regular 24V power adapter is used to power the amp, would you happen to know how to power the 12V mixer from the same power source? Could I use DC/DC converter to convert to 12V from a single-rail 24V power supply while at the same time using it to power a 24V amp? Thanks.

vermeuliscious made it!7 months ago

I'm almost finished with my solar powered adaptation of this project. I used 48 reclaimed lithium ion batteries, a battery protection board from allbatteries, the rolls mixer, a a 30w panel and solar charge controller I got on ebay, a DC boost converter to supply a steady 39v to my 2 channel amplifier, and a pair of PR12 speakers. One thing i'm noticeing though is that despite some very impressive music volume, there really isn't much low end punch. This is of course the tradeoff with light, efficient stuff, but I'm searching for a relatively easy solution. One thing I'm considering is salvaging a computer or home theatre subwoofer and adding a second amp to drive it. I may not have time before burning man 2014 but we'll see.

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what amp are you using?
if you need more power pioneers gmd 8056 is a good effecient amp with low power consumption.
instead of using the speaker from a sub, look at the free design of cubo 12 or 15 or tham12 or 15.
a normal hifi or car subwoofer only has an spl at 88-90.
I wound up building the separate sub-woofer from a very efficient and punchy 8" computer sub. Unfortunately I got all the way through hooking that up and STILL had no low end. It turned out the Rolls MX-51 completely attenuates the bottom end of the signal. I was very unhappy when I discovered that and as such I would very much NOT recommend the mx-51. Instead I swapped it out for a pioneer under-dash signal processor ($29 and works much better than the rolls). The sure-hifi power amplifier didn't last long at high volume in the desert heat (this was Burning Man project) unfortunately, and I'm looking into upgrading to a more powerful hifimediy unit.

Had you tried to take a look at the Pioneer gmd-8056 class-D amp, it's very popular in the mobile soundsystem community in Denmark.
It's very effecient.

Can be bridge to 300 watt.
It uses about 4A, in a 2.2 setup, with two tops and two subs.:)

royb14 months ago

The D in Class-D amps does not stand for "digital", it was just the next letter after C.

A tupperware box is a bad choice for anything that generates heat, it absorbs heat, deforms, melts.

The Peavey PR15N is rated at 400w RMS, why are you using such small amps?? If you don't give them enough power they're just going to drain batteries while sounding bad.

I really don't think the author knew what he was doing, which also doesn't seem safe.

Sureelectronics seems to have discontinued making it's TK2050 amplifiers. I'm assuming that the technology could only have gotten better, but i'm not sure where to start looking. Does anyone know what the 2014 equivalent of the sureelectronics improved TK2050 amp would be?

Is this what you're looking for?

http://www.dx.com/p/4-x-100w-4ohm-tk2050-class-d-audio-amplifier-board-black-204167

I actually found a 2050 based amp that does 80W x 2channels at 39v into an 8ohm woofer. That newer sure amp looks like it would do the trick though.

joshuaehayes10 months ago
Hey dan can you make a instructtable for me that I'm trying to make or tell me the best way to make it? I hunt and need a easy effective way to have a couple speakers maybe 6x9 and hook them up to an amp and power supply to hook up with my iphone. I have a app that has hunting calls and need a way to have good loud sound to make the noise be heard good... On hand all I have is a mtx car amp and car battery and 6x9 speakers. I am in desperate need of a goo way to make a portable system for hunting purposes... Please help me!!!
chriscab3 years ago
Thanks for the great instructions, Dan! Last night I debuted my setup with a TA2020, 12v/8Ah SLA & Gemini RS-308, created from your wonderful instructables, at the SF Bike Party and it was definitely a success. Got some great comments from people who were impressed with the sound coming from such a compact package. No trailer or car batteries for me, everything was mounted on my rear rack. I'll post pics later. Now with this portable powerhouse, tailgating and bbq picnics will be even more of a party!

So of course, I've now gotten the bug on wanting to get louder and cleaner. I'd like to upgrade to the TK2050 with the monoXover and another SLA. My question is: To get full power from the amp with 24V, I'd still need a pre-amp to boost the signal going to the amp, correct? And if so, should it go between the source/MP3 player & x-over, or x-over & amp?
Chriscab, did you ever get any advice on this question? I am doing a similar set-up and am also wondering where the pre-amp/mixer should go.
dan (author)  kristoballa071 year ago
put the pre-amp right after the mp3 player. see STEP 5, the 'mini mixer' i used has a built in pre-amp that works great for this.
smellex1231 year ago
is it worth running this from a 12v supply? i want to create a system to run off solar for my truck which has a 12v battery bank. My idea was to build(or get someone i know can) too create a 2 or 3 way crossover that sits before the amps and send the low to an active sub with the TK 2050 and use ta2021 fo the mid and a ta2020 for the high channel.Can you see any flaws in my logic? from what i read somewhere i got in my head that the tk2050 will only run at about 20% at 12v which is not what i want as the music i listen too is all about bass!!! is that right?
smellex1231 year ago
Hey dan wicked work here!! i've just bought two amps the ta2021 and ta 2020 from the indeed hi fi matey. Im thinking is it possible to wire it so the stereo input goes through the crossover first and then run the low freq into a sub box, of maybe say the ta201 amp wires up to 2 small woofers or 1 slightly larger woofer and use the mini ta2020 to run the high freq with a couple of 6x9s?
codesmith1 year ago
re: is their a way to have the portable sound system run off of a power supply and charge the battery at the same time?

Sure, if I understand your question. You need a solar panel, decent charge controller, and some sun. The panel, battery, and load (the sound system's amp) all connect to the charge controller. It can charge the battery and supply power to the load at the same time.
Sorry to necropost, but is their a way to have the portable sound system run off of a power supply and charge the battery at the same time?
Hey, did you ever get an answer to your question? I'm wondering the same thing...
This system worked perfectly with an ipod as a source but when I tried playing music from my laptop, I got a very disturbing hissing noise. I suspect a grounding problem but I have no clue about how the ground my 24V Sla battery to my aluminium mac... any idea?
panasuiks1 year ago
I'm running into the same mental block that tamadoctor did. Both the woofer and the horn in the B212XL's are rated at 8 ohms. If we use the TK2050 as an integrated amplifier, won't both the woofer and the horn only receive 40w-60w of power? Hopefully I'm just missing something...
fernandonh2 years ago
Would you have any additional instructions on the process of connecting the battery to the amp? I purchased the speaker, monoxover and the TK2050 and I will be installing the crossover before the amp as you instructed. I am just a bit lost on connecting the batter to the amp.

Thank you so much!
fernandonh2 years ago
I found an used active Behringer B212a and I wonder if I can do the same project on that one. Do you think I can use the amp that is already inside the B212a plus the MonoXover?

sweber12 years ago
Thumbs up to Dan and a little update from denmark.
Last summer me and my friends stumbled across this tutorial - and i just wanted to share our result with all of you, and Dan. This project was completed in a couple of months, we are now building a high efficient woofer to go with the system.

We went with a couple of behringer b212xl speakers - they were available used for a cheap price and have a fairly high efficiency . Installed the monkey electronics filter and a sure electronics 2x150w amp in each speaker as covered in this tutorial.
The DJ case consist of a welded steel frame as we wanted to fill this baby with acid-fluid power (read: car batteries). It can contain 7 batteries, delivering about 400Ah at 12v. We've installed a 17" inch tft monitor, which ran native 12v input through an expensive dc-dc converter to output precise 12v as the monitor needed. A computer on 12v from fitpc (in retrospective it's too slow for DJ apps - but great for winamp.. Actually an ipod would have been sufficient). We also found a nice 3 channel 12v mixer to put in.

The system can run approx 10 hours on 3 car batteries on 80% volume.

Iv'e learned that noise in this ungrounded system can be a bitch. The dc-dc converter made so much noise along with the tft that we needed to put it on seperate batteries to reduce the noise transmission from them. Also using a trafo between speaker and mixer helped a lot. And of course shielded cables.

We held a nice party for around 150 people as you can see in the images.

cheers
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dofnicom2 years ago
Could you take this concept and create a rechargeable wireless speaker by mounting a battery in the speaker and adding a UHF Wireless Mic Receiver to the equation like a Nady DKW-8U. I am a DJ and sometimes I need remote fill speakers in weird places. A self contained powered wireless speaker would be nice. 8" or 10" with the 100Watt amp and wireless receiver. The receiver is DC14V 0.4A.
fatdumpa2 years ago
great article. very comprehensive. iv had this hi-fi speaker lying around for ages, using it to put drinks on. so i think il have a stab a powered mono speaker, maybe with one of these cheepies, (any good?)

http://www.ebay.com.au/itm/230608706091?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649#ht_3755wt_907

and one of those

http://store.monkeylectric.com/ProductDetails.asp?ProductCode=XOVER1

both mounted in the box, and a 12 volt battery yet to be acquired.
any of you experts know what kind of volumes i can expect from this kind of set up?
the speaker isn't massive i know, but it's a convenient size, and i can always swap it out for a bigger one.
Photo on 2012-04-02 at 15.42.jpg
What do you think...a car battery with an inverter, a powered PA speaker with the two amps pushing out 200w total and two guitar amps - a 30 watt and a 60 watt. How long would this last us? This will be on the back of a pickup truck.

Any feedback would be huge.
ivica123 years ago
Hi!

I am new to this so I have a couple of questions. Would it be a problem to connect 4 ohm speakers? I'm looking at these specifically http://www.thomann.de/gb/peavey_pro12_messengerserie.htm

Also, these seem cheap and have a big SPL, however the brand is unknown (and obviously being much cheaper than others I am a bit worried about the quality) http://www.thomann.de/at/the_box_pa15eco_mkii.htm

Thanks for the help!!
n0ukf ivica123 years ago
Most amps have a range of acceptable impedance they can drive (like 4-16, read your amp's specs). If your amp only goes down to 8 ohms output and you can use two speakers per channel, you connect the two 4 ohm speakers in series. If 4ohms is the maximum output impedance and you have two 8 ohm speakers, connect them in parallel.
lol i thought that it was a wheel chair connected to a bike with speakers on it. IDEA! the sound-chair!
Thanks for the idea! Time to go wheelchair hunting! Maybe electric?
dfuller113 years ago
I have obtained 2 SLA batteries (from computer back-up systems). They are marked "Cycle Use" 14.5-14.9V ("Standby use" 13.6-13.8V).
They are hardwired w/ a nylon plug with three terminals (marked "+"," -", and "S" (ground?)).

Anyhow, I have been unable to get them to take a charge from the 12V charger I have. Perhaps I need a more powerful charger? How should I treat the "S" terminal? (see photos).

Many thanks.
SLA SLA
Elorrum3 years ago
Lepai makes a small 2.1 amp, probably ta2020? that I used with 8AA batteries, 2" 4ohm speakers mounted in PVC 3" pipes, a DVC subwoofer built into a plastic bucket lined with batting. great near field, and loud enough for shouts from 50 yrds to "turn it up" but not loud enough to do so. Working with a sure 100W 24v amp with line arrays in composite fence posts as next project.
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