I certainly agree, probably for you and I..lol...I don't know the physical abilities of the OP, but if they want to carry a portable pa 10 miles...well, I thought it would be a challenge to solve that one. Class d amplification and NEO sounds like a must. I suggested the S400 due to sound quality and onboard 12v rechargable power supply..and it is hard to find anything powered for less than 34 lbs...maybe this:
Who Needs An iPhone Speaker, When You Got A Bullhorn? | Co. Design
Backpack system
A chunk of sonotube with a half way decent speaker would be about as lite as you can get and easy to fabricate. Add a li-po battery and T-amp then rock on.
I saw some backpacks with speakers built in for $20 at the discount store, looked like cheap clock radio speakers but they are out there.
A chunk of sonotube with a half way decent speaker would be about as lite as you can get and easy to fabricate. Add a li-po battery and T-amp then rock on.
I saw some backpacks with speakers built in for $20 at the discount store, looked like cheap clock radio speakers but they are out there.
A 10(ish) watt T-amp like a TA2024 or preferably Arjen Helder's TA2020 which implements the "overload" pin, so you have a clipping indicator. For proof of concept, a $12 (shipped) TA2024 amp should be fine.
An efficient speaker. 6" to 8", maybe Eminence or some house brand thing from Parts Express. Since it's a 2-channel amp biamping may be worth the effort; it should yield more headroom. So, some equally efficient semi pro horn tweeter. For an active crossover, maybe DIY a 4th order. Or a used car active crossover; those sometimes turn up at thrift stores and yard sales.
Enclosure... stiff but light. Sonotube with the tweeter mounted outboard on a bracket (or using a front baffle that extends past the tube). Thin ply bent over a top/bottom/front made of heavier ply?
Fiberglass jellybean shape?
Maybe this is the way: Doublethick corrugated cardboard for the top & bottom & curved back/sides. Maybe curve the top as well; leave bottom flat or angle it stage-monitor-style. Front baffle... maybe 1/4" ply front, and skeletonized ply on the inside since it'll hold T-nuts more securely than cardboard will. Finish with fiberglass, or possibly just resin. Maybe Formica or Arborite if they can bend enough.
Glass-epoxy circuit board stock is extremely tough and bendy; perhaps that could be used for curved panels. Lace the joints with wire (technique I've seen used for small boats to join plywood) and seal with something.
Anyway, it's late, and those are some ideas that have crawled from my fuzzy brain. Unless the aliens or Great Old Ones implanted them again. But it's hard to tell. Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
An efficient speaker. 6" to 8", maybe Eminence or some house brand thing from Parts Express. Since it's a 2-channel amp biamping may be worth the effort; it should yield more headroom. So, some equally efficient semi pro horn tweeter. For an active crossover, maybe DIY a 4th order. Or a used car active crossover; those sometimes turn up at thrift stores and yard sales.
Enclosure... stiff but light. Sonotube with the tweeter mounted outboard on a bracket (or using a front baffle that extends past the tube). Thin ply bent over a top/bottom/front made of heavier ply?
Fiberglass jellybean shape?
Maybe this is the way: Doublethick corrugated cardboard for the top & bottom & curved back/sides. Maybe curve the top as well; leave bottom flat or angle it stage-monitor-style. Front baffle... maybe 1/4" ply front, and skeletonized ply on the inside since it'll hold T-nuts more securely than cardboard will. Finish with fiberglass, or possibly just resin. Maybe Formica or Arborite if they can bend enough.
Glass-epoxy circuit board stock is extremely tough and bendy; perhaps that could be used for curved panels. Lace the joints with wire (technique I've seen used for small boats to join plywood) and seal with something.
Anyway, it's late, and those are some ideas that have crawled from my fuzzy brain. Unless the aliens or Great Old Ones implanted them again. But it's hard to tell. Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
Battery: 12V sealed lead-acid are simple to charge. The common 12V 7AH size should give plenty of run-time. Bulk alkalines might be cost effective for occasional use. NiMH if you have a smart charger and can buy 'em sufficiently cheap. Beware of eBay "NiMH" from China; many are fakes. There may be deals on orphaned battery packs from cordless tools on the bargain tables of hardware stores.
Possibly use a hand-cranked electric motor to recharge on-site; an old cordless drill already has the PM motor and gearing: put a crank on the chuck. Use a rectifier to isolate it. A cheap LCD voltmeter would be a good idea to monitor battery status (voltage); current would be useful to monitor charging so the person cranking knows if they're going fast enough. Maybe just a 1 ohm resistor in series with the generator and then a 100 ohm (wild guess) resistor and LED across that. A red LED should just start glowing once there's about 1.6 amps through the resistor.
For no-budget batteries, scoop some scrapped sealed-lead acid batteries from the recycling bin behind a battery store. Charge them and test them with a load. (Ideally, measure capacity... I once did that using a borrowed ADC card in an Apple II clone and a BASIC program that logged voltage over time then beeped to tell me to disconnect the load when some cutoff voltage was reached.) Sometimes only one battery of a pair is bad, but people replace both for safety, so it's not completely unlikely to find a good battery. Often just one cell in a battery is toast; it's possible to dig into the top and expose the lead connecting link between cells and solder to it. One "10V" plus one "4V" gives you a battery with about the same voltage you'd find in a car with the engine running. I think it's within the spec of the T-amps.
Possibly use a hand-cranked electric motor to recharge on-site; an old cordless drill already has the PM motor and gearing: put a crank on the chuck. Use a rectifier to isolate it. A cheap LCD voltmeter would be a good idea to monitor battery status (voltage); current would be useful to monitor charging so the person cranking knows if they're going fast enough. Maybe just a 1 ohm resistor in series with the generator and then a 100 ohm (wild guess) resistor and LED across that. A red LED should just start glowing once there's about 1.6 amps through the resistor.
For no-budget batteries, scoop some scrapped sealed-lead acid batteries from the recycling bin behind a battery store. Charge them and test them with a load. (Ideally, measure capacity... I once did that using a borrowed ADC card in an Apple II clone and a BASIC program that logged voltage over time then beeped to tell me to disconnect the load when some cutoff voltage was reached.) Sometimes only one battery of a pair is bad, but people replace both for safety, so it's not completely unlikely to find a good battery. Often just one cell in a battery is toast; it's possible to dig into the top and expose the lead connecting link between cells and solder to it. One "10V" plus one "4V" gives you a battery with about the same voltage you'd find in a car with the engine running. I think it's within the spec of the T-amps.
Further thoughts... a pneumatic-tired hand truck can haul a lot of weight over moderately rough terrain and up or down stairs if it has the skid rails on the back. A 15" powered monitor or two plus a tiny generator (800 to 1200W) should be a feasible load.
Humans with pack frames can haul stuff over extremely rough terrain. Two people packing powered monitors, one person with the genny.
Humans with pack frames can haul stuff over extremely rough terrain. Two people packing powered monitors, one person with the genny.
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