edit: i am posting up some peoples systems to get the ball rolling, let me know if you want a takedown for any reason - PM me :)

http://forum.speakerplans.com/portable-system-build-pics-finished-pretty-much_topic29102_post291064.html?KW=#291064 - http://forum.speakerplans.com/portable-system-build-pics-finished-pretty-much_topic29102_post291064.html?KW=#291064

http://forum.speakerplans.com/12v-portable-soundsystem_topic29684_page1.html - http://forum.speakerplans.com/12v-portable-soundsystem_topic29684_page1.html

http://forum.speakerplans.com/trolly-soundsystem-mini-line-array-with-photos_topic27593_page1.html - http://forum.speakerplans.com/trolly-soundsystem-mini-line-array-with-photos_topic27593_page1.html

http://%20forum.speakerplans.com/the-best-home-made-ipod-dock-ever_topic28984_page1.html -

http://%20forum.speakerplans.com/the-best-home-made-ipod-dock-ever_topic28984_page1.html - http://forum.speakerplans.com/the-best-home-made-ipod-dock-ever_topic28984_page1.html

http://forum.speakerplans.com/another-12v-system_topic27845.html - http://forum.speakerplans.com/another-12v-system_topic27845.html

http://forum.speakerplans.com/my-new-system_topic27725.html - http://forum.speakerplans.com/my-new-system_topic27725.html

http://forum.speakerplans.com/another-12v-mini-rig_topic26056.html - http://forum.speakerplans.com/another-12v-mini-rig_topic26056.html

http://forum.speakerplans.com/another-12v-mini-rig_topic26056_page3.html - http://forum.speakerplans.com/another-12v-mini-rig_topic26056_page3.html

http://forum.speakerplans.com/another-12v-mini-rig_topic26056_page3.html - http://forum.speakerplans.com/another-12v-mini-rig_topic26056_page3.html

http://forum.speakerplans.com/show-off-your-sound-system_topic2179_page692.html - http://forum.speakerplans.com/show-off-your-sound-system_topic2179_page692.html

http://forum.speakerplans.com/12v-tek_topic28517_page4.html - http://forum.speakerplans.com/12v-tek_topic28517_page4.html

http://forum.speakerplans.com/12v-tek_topic28517_page5.html - http://forum.speakerplans.com/12v-tek_topic28517_page5.html

Hahahaha

 

 

Lithium Powered Amprack (3 way) bass-50-200, mid - 200-3500, high 3500-20000

21ah lithium (16.8v) 40 cells.  Fully Class D - 12hrs use 

little gradation party i did on the university campus fields kinda 12 volt running of an inverter and a couple of tractor batterys

mhmmmm 

had them both running together today.  very good sound and very punchy indeed.

scourge of shamania festival and companion on many an adventure. the little philips speakers (late of the national centre for popular music) are bob on, sadly one of them got a bit wet at glade 07, but what didn't? the sub is a fairly interesting series tuned 6th order effort from tannoy, being a cpa5-sb, the internal passive crossovers make it a cinch to use without complex amplification solutions, a boon for 12 volt use. there used to be little brackets with them and bolting them to the hubs of the geodesic dome made for an excellent festival lounge.

a new 12 volt rig is currently in the offing: designed around a push-bike trailer concept it's debut on the sheffield scene is long overdue, but then again everything i'm involved in generally is. hey-ho...

james.

i just ebayed a kenwood kac9152d for the bass section, it's one of the few true monoblock designs that can be bridged with another unit, giving us a modular upgrade route that won't break the bank. i'm building around a 6 ohm phl 15" and the kenwood should give me at least 300 watts with that kind of load (which in a high efficiency enclosure should give us bass we can work with), annoyingly the lpf only goes up to 200 Hz and i intended to cross at 250-ish, but i kind of gave up waiting for a suitable unit to crop up at the right price.

i've seen some really nice cycle powered generators of late which has given me a few ideas. if we could tow one of those around with us too then not only could we carry fewer batteries, but the greater supply voltage of ~14.6 during charging gets a good 30% more welly out of all the amps, although we might need to look into a 1.0 farad cap to keep the current to the bass amp(s) more consistent during transient peeks. come to think of it, my old martin 215 mkIIs are full of baked bean tin sized caps, shove all 12 of them in parallel on some nice solid copper rails and we'd be cooking with gas.

james.

 

over 12v is where the party starts.  my memphis will take 16volt all day and burp use at 18volt.  the power output apparently get huge at 16v but it gets warm so i have fitted a 12v fan.

where you based james?  did you say you were in bristol? 

what i'm really surprised to hear is your feelings on braked trailers. living in the peak district the the concept of towing 100 kg un-braked is practically unthinkable. i've had some bad experience towing various trailers with my land-rover, the worst of which happened on an un-braked and overloaded sankey and i ended up leaving the road very unceremoniously.

we're not building the system to fit a trailer, we're using the cab itself as a stressed member and bolting the wheels on the sides, saving weight and allowing the centre of mass to be lowered over a conventional flatbed trailer. 26" mountain bike wheels from the scrap pile are to be employed, the hitching system will be based on others that use the drop-outs, i've also found that works best.

you may well turn out to be correct about the trailer brake, but i'm not prepared to omit it from the design at the moment!

james.

...not that i'm sure it will be necessary. i had a little play with a new maystar amp that i bought by accident, turns out it was a happy accident.

this cx255 model has rather handy filters on the input and pass-through connectors. feeding that with a laptop driving full range toa install boxes, pass-through connectors feeding the ageing sanyo amp which was bridged into a single 15" reflex. when i hooked the battery up and had a blast i was refreshingly surprised. the bass was getting less than 100 watts, the tops about 20 each and the room was getting a good workout. output for the size and power was superb, but what really won me over was the quality. the toas are lovely little cabs and the bass is a p-audio bm-15lf (one of their really sweet drivers) tuned fairly nicely so the ingredients were there, the amps filled in the rest of the equation and left me with a big smile. the bass particularly had a really warm tone without loosing good tight control of the cone, and this is on a fairly entry level bit of kit.

but yeah, already fairly loud and really pretty sweet! i've not been so excited about a pa project in years, i have a feeling it's going to see a lot of action in the future as we are forced in to more discrete and elusive small-scale partying. stealth parties... oxymoronic, but a noble enough goal.

james.

 

im loving your power wire...:)  5amp is that? lol.  im the same, put a thin power wire in as makeshift and then when you want to turn it up it ends up getting warm.   and i bet you cranked the system so it was pulling 20a at times.. haha

 

nice to hear it all is working nice.  something very satisfying when you get a battery powered system that doesnt sound like its running from a battery

 

Its a type of three wheel cargo bike invented in the carless autonomous area of Copenhagen called Christiana.

 

 

 

http://www.christianiabikes.com - http://www.christianiabikes.com

 

i wondered if anyone would comment on the "silly string"... it's 2 x 0.75 mm, pretty weedy but it's what we used to use for 100 V line installs so i have - or at least had - a fair few miles of it knocking about. the real thing will of course use super-chonging fat boy cable, of whatever kind is handiest when building...

 

james.

right... now i've been mulling this over for a while and i think i've come up with an explanation.

your system runs from static battery voltage, that being in the order of 12.5 volts. the only thing that stops the voltage sagging when the bas kicks is the battery's ability to deliver current. since this is nothing like the order of magnitude of cranking current, even deep cycle batteries can probably manage it with ease, especially if you've been a good boy and wired your system with fatty boom-batty cable. which you have...

however, if your system is running at charging voltage of around 14.6, the only thing that is holding the fort for those last couple of volts is the charging system itself, namely the alternator and by extension of thus, the person pedalling's legs! this is where your capacitor bank comes in, it's there to stop the voltage dropping from that higher value and correspondingly to lighten the load on the alternator and associated circuits, charging up again in times of surplus.

hence you are right: if you are running a static voltage system then no, a cap won't make any difference.

james.

so it would be right to assume that any portable system where a capacitor may indeed have a positive effect on the sound quality would probably gain a benefit because their actual battery is unable to perform? 

 

so a system capable of drawing more current (during its intended use) than its fully charged battery can deliver would ideally benefit a lot more from an increase in battery cranking power and capacity instead of adding a cap? 

 

 

having said that, if rapid draw is bad for your battery system the capacitor might well take some of the strain off it. it'll still use the same amount of power of course, but that power might be spread out in a beneficial way.

 

@ sam and james-

 

i thought about this a lot and was wondering if a cap has any noticable loss in terms of heatup or leakage?  if it is near 100% efficient could it be assumed that a cap will add to the running times of a smaller sla that has its capacity rating measured at a lower current draw than how it is being used in the real world?  will the slight smoothing of the current draw have a noticeable positive effect on the discharge rate (assuming most battery capacities are measured at a discharge rate lower than the rate we are probably going to use them at in portable audio)

that indeed is the question. as sam pointed out the cap will be recharged by the battery too, so is the smoothing effect even there? i guess it has to be as the amps will draw power from both sources during the transient and only when it has passed will the cap recharge, but as to what real world difference it might make to run time, you'd have to proper science it to find out.

the internal resistance of the batteries is probably not a million miles off that of the cap, although that is speculation, whatever it's bound to be significantly less than that of the charging system so i'm quite sure the amps will draw more from the cap than the alternator. i need to do some research on alternator speeds and cadences, see if i can't figure out a gear range that will offer usable power across the optimal voltage range for the system. i think the trick is going to be making sure that even in the lowest gear you are running at about 13 volts at a sustainably relaxed yet purposeful pace.

ironically, the complexities of the pedal generator have now far outstripped those of the audio system, but i've totally sold myself on the idea. i need to get a kWh meter in there somewhere to calibrate shift changes during parties... but yeah, the extra power is one thing, however the leap to true sustainability is the winning hand.

james.

 

so yes, predominantly static, possibly having to power an inverter for decks and a bit of led lighting on top of the amplifiers at times too. it is likely that we might be set up at these locations for over 12 hours at a time, that being the case the choices boil down to: pussyo stereo with long battery life, nails stereo with laughably short run time, nails stereo with all the batteries in the world, or nails stereo and power generation system.

 

those batcaps are the coolest thing... plus they do a 25 farad capacitor, yikes! if we ever get to the point of doing spl comps with our 12 volt rigs that kind of thing is going to be essential tackle.

 

james.

 Thanks for posting the orange rig... i love that beast! I guess i should add:

upgraded version of the ultimate 12v mobile disco. note its is now a bar complete with lockable drinks cabinet. It has an LED lighting system at night complete with disco ball and bubble machine. I ruggedised the amp module but kept the speakers the same. It rinsed it again at shambala this year, has over 100 people dancing to it at the parade. :)

This is the mark 2 minirig. 4ohm Neo driver, 12w class-d amp and 3-cell 1500mah lipo battery. weighs just 400g, ridiculously loud for its size. charges from Mini-USB with a custom smart charger and lasts like 100 hours between charges. just need to find a grill now!

many more photos i'l try to add soon. more designs in the pipeline!

cool.  so very little power into some 109db efficient components.  makes me want to remake another unity horn soon.  miss my one now its sold:(

you gonna be available in the summer for a 12v linkup?  southwest england, likely to be bristol, or devon.  gonna stash a big pile of sla's at the location prior to the event so should have a nice stockpile of ah's..  would be great to get a nice pile of 12v rigs going.  seems most 12v events have been randomly put together pro audio cabs running of car amps, instead of systems primarily designed for 12v.  

 

One thing to note; drive them too hard and they cut out for several minutes before rebooting, had this problem when pounding the ass off a JL 15, quickly solved by coupling them together.

As to the power cap discussion, would the cap not add an extra load to the battery on top of that already being put on by the amp, during a long or very heavy bass transient?

Have found this on ebay: http://cgi.ebay.co.uk/180-AMP-NEW-12V-QUALITY-LEISURE-BATTERY-CARAVAN-BOAT_W0QQitemZ110438371318QQcategoryZ108845QQcmdZViewItemQQ_trksidZm263QQ_trkparmsZalgo%3DSIC%26its%3DI%26itu%3DUCI%252BIA%252BUA%252BIEW%252BFICS%252BUFI%26otn%3D20%26ps%3D50 - http://cgi.ebay.co.uk/180-AMP-NEW-12V-QUALITY-LEISURE-BATTERY-CARAVAN-BOAT_W0QQitemZ110438371318QQcategoryZ108845QQcmdZViewItemQQ_trksidZm263QQ_trkparmsZalgo%3DSIC%26its%3DI%26itu%3DUCI%252BIA%252BUA%252BIEW%252BFICS%252BUFI%26otn%3D20%26ps%3D50

A 180 Amp leisure battery for £120. Thoughts anyone? good price?

 

id imagine an elecsol 100ah battery @ £100 will be a better option seeing as 180ah is probably overkill in terms of capacity for a portable system. the 180ah of this leisure battery weighs in at 45kg = 2x PD1850's!!!. 100ah of elecsol weights 20kg.

 

Most lead acid batteries are extremely good at supplying huge amounts of current for short periods of time, this is why they are good at turning over vehicle engines to get them to fire. So why would an amplifier need a cap to get the necessary juice out of the battery?

 

Most decent batteries can cold crank in excess of 500a and the bigger ones can do in excess of 1000a. 500a at 12v is 6,000w, and 1000a is 12,000w surely people don't need help from a bank of caps to get more power? If a battery can turn over a diesel engine for a few seconds at 3000rpm I fail to see why it would have problems supplying enough power to move even the biggest 5inch voice coils at 50Hz

 

The cabling on low voltage supplies is a bit of a mystery to some people and so my guess is that they are using power cables to their amps which are too small. To undecuated people it is difficult to diagnose when the cable is too small because the amp will continue to work and the cable will not get hot but if the x-sectional area isn't large enough for the current then the voltage drop will be too high.

 

I'm guessing people are misdiagnosing voltage drop as a battery problem and rather than replacing the cable with something suitable, they are simply adding a cap to boost the voltage nearer the amp. Both will work but I know where I'd spend my money

 

Using a power cap in a car can in some situations cause more harm than good. Yes, it can store and discharge power at phenomenal rates which is exactly what the subs and amps want, but in some cases the power is being drawn from the battery too quickly by the capacitor and in turn puts extra strain on the alternator and battery. A little bit of extra bass vs dead battery and alternator...? No thanks!

Split charge systems are the way, then using a cap is probably worth while, but im sure these companies are making loads of cash off of little rude boys thinking they are the dogs and all that...

 

also, i think the cap popularity began before class d bass amps became a normality.  back when earthquake/audiobahn etc were bringing out 1kwrms in class ab amps.  These types have died a death since class d has become popular 

 

selling due to completely new project in pipeline.

 

s

 

 

http://forum.speakerplans.com/portable-sound-system_topic25442&OB=DESC_page10.html

 

http://www.talkaudio.co.uk/vbb/showthread.php?t=166573 - http://www.talkaudio.co.uk/vbb/showthread.php?t=166573

 

Still thinking I  might make a new one... and now I've found this thread there's plenty of new tricks to absorb!

 

Ha Ha HA! I've just spied the discman in the first photo!  I think I've still got that somewhere....

It's not new but it's quite exclusive and the best thing is if they even have a inkling you work in the city they don't let you in lol. They also don't allow suits.