And Now For Something Completely Different...

[Traijin]

I have my pair of Jack 115's up and running and hosted a party this weekend with a menagerie of folks. I received all sorts of comments from sound clarity to the look of the Duratex.

A few folks were impressed enough to ask some recommendations for a specialty project.

Columbus Ohio has a large group of Bicycle enthusiasts. They advocate bicycle awareness and usage all over the State. There is an organized Co-op for the Bicycle group that organizes parties, display booths, charity drives, etc.

This group is interested in a stereo system that is trailer mounted which can be towed behind a bike. Likely a Pedal-Taxi, so the gearing is low and I would guess a maximum weight limit around 200-250 Lbs.

This is an environmentally motivated group as well, a gas burning gen-set is not an option. This will be run off of lead acid batteries. These can hit the weight limit very quickly.

So, this system will likely 12 volt, obviously depending on how the batteries are wired.

The group has stated they want this as a DJ style setup with the ability to spin vinyl. I think the whole spinning vinyl is the biggest problem. Locating low voltage turn tables and mixers may prove impossible. Perhaps an inverter, but it could kill the juice quick.

A system like this will also need voltage regulators to avoid voltage drops/amperage spikes as the batteries drain, wouldn't it?

Anyway... They want bass reproduction. A horn loaded subwoofer sounds like a logical solution. This site is the home of some of the most sensitive subs available. And a grouping of folks that might be willing to help me think through all this.

1) Trailer Mounted portable, it will not be in operation under movement.

2) 200-250 Lbs weight limit

3) Tops and Subs

4) Low voltage Crossover?

5) Low voltage EQ?

6) Definitely iPod or computer playback

7) Vinyl (Turn tables and a mixer) I'm not seeing a way for this to work though. Maybe an inverter.

Voltage regulation to avoid equipment damage.


I am a general contractor by trade, When I use the term low voltage I simply mean below 110 volt.

I know this is bizarre, but I think some of it is possible.

Thoughts?

Thanks

[Dan30]

Why not biodiesel in a generator?

[Traijin]

Cost and the principle of bicycles over engines. They would prefer not to have internal combustion driven generation.

If I could rig up a genset efficient enough to be powered by a pedaling human, then I would have something. Yeah... that'll be the day...

[el_ingeniero]

Easy-peasy-cheezy:

* 2 DR200 + 2 T39, using neo drivers, fabbed from fiberglass/foam composite
* Automobile amps
* Put together your own giant 12V battery pack from lithium-ion batteries
* use a laptop to DJ, using one of those auto/airplane/AC battery packs.
* Build a human powered generator, just have a dozen or so cranks and you have a couple of horsepower on tap. Put wheels on it and make it so the enegy from the cranks can be switched between the generator and the wheels, and it becomes self mobile too.

[Traijin]

DRs and Titans are the way to go. Trying to play the fibre-glass game maybe a bigger ordeal than this group could want to take on or it could become a bigger mess than I would want to fix in the future.

I agree car amp is the way to go. The head units used to have the cross overs. Do some of the amps? Is there a car crossover than can be set with multiple outputs? Is there an EQ? It would be needed with the DR's.

A LIon battery group sounds like a lot of effort. Lead acid is available and easy to charge. Even if the weight creeped up to 300 lbs, it would not be the end of the world.

This bike group already has display with bike frames and humans making 100 watt light bulbs glow... I think it is nothing more than a mental exercise. I don't plan on putting any effort into making the system actually make power for the project.

I still think voltage regulation will be important, especially if I use an inverter to run a couple turn tables and a mixer.



*** I see a mixer and two turn tables use very little wattage. They average about 10 watts each. I also see an inverter with built in voltage warnings and cut offs. Like this:

http://www.parts-express.com/pe/showdet ... er=125-320

If I took one of these amps for these DRs and another for the Titans:

http://www.parts-express.com/pe/showdet ... r=267-7134


Ran the signal through this before the amps but only use two of the channels:

http://www.parts-express.com/pe/showdet ... er=267-822

But before the Crossover run the signal through this some kind of EQ.

What this is all missing is a limiter for the subs...


I would probably try running it with three or four of these batteries. That would make 105 to 140 amp-hours. They are deep cell and weigh in at about 23 pounds each.

http://www.solar-electric.com/unba35amseag.html

[Rick Lee]

What kind of coverage do you need?

[Traijin]

I don't think its a lot. Out side of information booths, parkings lots of small business's. a few hundred square feet. But they want room for scalability. I had initially thought about SLA pros and some subs. I think the sensitivity of the DRs wins the day.

[petegt]

For eq and crossovers I would highly recommend the Mini DSP: http://minidsp.com/products/minidspkits/2-x-in-4-x-out

Will do everything you want and more, uses a minuscule amount of power and will run happily between 4.5-24V

I have used my system at a friends farm running from very large 12v batterys from a motorhome. I used a car amps with the mini dsp, jbl gto 4000 4x75Wrms for running tannoy 605 hifi speakers active and an alpine mrd 300 class d mono amp 150Wrms powering 2 V plated TAT's.

This set up produced impressive volume and battery life.

Im sure you can make an even more efficient system with the titans and dr's that others are suggesting

There is a section on the speakerplans.com forum about 12V systems (Definitely not a preferred forum but allot of useful knowledge in the 12v section) They all seem to be very keen on class D or Class T tripath amplifier modules for the best combination of battery life and power. Allot of them are using modules made by sure electronics, there is a 2 x 100Wrms or 4 x 100 W rmshttp://www.ebay.co.uk/itm/2-100w-TK2050 ... 1189wt_957

I think a combination of Tripath/class D amps, minidsp, titans and dr's would make a very efficient system