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500 watt BICYCLE "steet party" trailer system with a JBL 15" sub

Posted by thump (A) on November 5, 2016 at 01:17:01

i am in the process of building a bicycle trailer street party system to combat the lousy gangsta rap/banda only scene here playing funkier and more upbeat funk, old school (REAL as in positive) hip-hop, nu-jazz, electro swing, disco & a little bit of techno. i've been working on the system for a while as i can afford it. i have almost everything i need to get it rolling except the sub/box, wiring, switches, circuit breaker, 3 more batteries, a charger, a power meter, and a frame to mount everything.

the system's main components will consist of:

- a sun EZ-1 recumbent bicycle that's a darker cobalt blue than the royal blue pictured that might become metallic purple eventually when i fix the backwards brake cabling. it doesn't just look cool, it's a super comfortable all day long ride

- a schwinn trailblazer trailer i originally bought because it was about the only trailer i could find wide enough to fit a pair of 2x12 boxes that would have faced upwards and featured 4 goldwood "93dB" woofers with a Q of about .7. it was a strenuous ordeal with much swearing fighting with the trailer to get the canvas off in one piece (not counting the seam rip the second time i used it to haul soda) along with the rollbars whose apparently superglued free spinning chrome moly bolts required 3 hacksaw blades to dispatch, but the frame is ready to get everything tossed on now.

- my source will be an xduoo X2 media player with a 16GB card playing uncompressed WAVs that will eventually get mounted on my handlebars for thumb control. it sounds pretty nice and i like both the aluminum case as well as the dedicated control buttons with machined edges that make it look more like a stereo component and less like a unibutton plastic toy.

- my mains will be a pair of italian proel flash8P 96dB 8" 2 ways that feature celestion drivers including titanium waveguide tweeters. i scored them for just $100 for the pair at MCM after researching proel sound and they sound VERY nice, especially in the midrange playing vocals, and are uncolored for PA speakers. the tweeters DON'T spit, at least not yet at home levels. they do sound a little thick on my PC driving a cheap (20wpc probably) vintage receiver, but they did open up noticeably when fed by the xduoo and i bet class D amplification will really let the otherwise quick on percussion tweeters open up and do the air thing.

they were originally intended to be temporary "get rolling now" speakers i could also pull from the system for stereo imaging (which they do pretty well actually nearfield, and without ear fatigue), but they sound so nice, and i expect them to maybe open up even more at volume that i think i'll keep them for a while for their efficiency as well as the ability to pull them out of the trailer and maybe even mount on poles.

- the sub will be a JBL GT15 92dB 15" in a 1.9 sealed box (i prefer clarity and speed over volume and extension) for a Q of 1.135, but that's EXACTLY what JBL recommends (1.5ft3 - 2ft3).

as i said, plan A was 4 x 12" goldwoods, but at $70 each, they would take time to acquire so i planned on a cheap MCM 15" poly with a rubber surround to be able to move the most air possible as soon as possible financially, but i wasn't liking the 50Hz driver limit and decided i'd upgrade to a better quality sub that digs deeper and can handle everything my amp can throw at it with two channels bridged (600w allegedly, i'll call it 300w real world)

at first, i was considering a VM audio elux 15 because it was rated the cheapest in a top ten list and did get favorable reviews, but i just wasn't liking its high 1.35Q and prominent 54Hz resonant peak or amp frying/choking 2x4 ohm coils.

then i tried browsing woofers by price until i got up to the JBL, ignoring anything with a foam surround and the hifonics brutus because i couldn't find thiele small parameters for it to see how it'd do in a 1.9 box.

the reviews were very positive for the JBL, it has a nice 27.5Hz rating, can take some power, has an amp friendly single 4 ohm coil, and best of all has a massive 14mm xmax. when i ran the numbers on it, it performed MUCH better than anything else i modeled that's when i knew i found a winner. it's a little gaudy looking to me with the "fancy molded dustcap" and logo and exposed basket/gasket, but i'm buying it for the performance, and in the final system, it will be pointing downwards for pavement coupling. i doubt i can find another sub that hits harder at $75 delivered.

- a planet audio BB1200.4 "1200w" 4 channel class D amplifier. ORIGINALLY i planned on using cheap sure modules, but they want high voltages. in another forum, everyone was shouting me down for wanting to use passive inline RCA filters and insisted i use an active crossover which created 3 problems... i couldn't afford dedicated crossovers, building an active one is beyond my technical abilities, & using a car EQ/crossover would require a separate 12v circuit requiring another battery to weigh things down.

the planet audio proved to be a "perfect" problem solver. it has a build in CONTINUOUSLY VARIABLE (!!!) HP/LP selectable filter on each pair of channels, bass boost (which would let me use just my bass starved proels to start with), would make finding a power meter much easier, with the simplification of going 12v from the start, i could easily add an EQ or power inverter for A/C lights. as each front/back pair of amps is also bridgeable, i could run my proels on the front channels and dial whatever sub(s) i'm using in on the rear channel bridged to mono for more power, and it would be more durable (if also much heavier) mounted on the underside of my trailer. i also like the simple looks of the amp and having planet in its name appeals to my tree hugger (recum)bent. (pun intended)

with 8 ohm mains and a sealed 4 ohm sub, the amp should see a very friendly load i don't intend to push. i'm looking into getting it SMD measured so it never goes into distortion. if the shop wants $100 to do that though, i'll pass and just use my ears. i don't like distortion at all. that's why i prefer sealed woofers. i'm not expecting it to meet it's power specs, but it's gotten great reviews, and at least to start, it should be more than enough to get people wondering what the heck a bike's doing thumping so hard.

- 4 x mighty max 12v 18aH ALLEGEDLY deep cycle AGM batteries. i already have 1. eventually, when i can afford it, i want to switch to li-poly. i chose this battery because it gets good reviews, offers about the best boom for my buck, & because they're small & can be mounted in any orientation. i intend to lay them on their backs, just behind the trailer frame for better weight distribution, lowering them below the frame for a lower center of gravity, and "stacking them" across the width with their terminals facing up so i can daisy chain them in parallel, but i bought a pair of distribution blocks too. i figured daisy chaining will use the least cable, so that's the better route to go and i can use the distribution blocks for adding an EQ and inverter etc. later using the 4 "ins" as outs.

finding a charger around $50 or less is proving a challenge though. even the highest rated chargers on amazon have up to 10% horror stories about chargers ruining batteries by undercharging or discharging them, boiling batteries, not having enough juice to charge anything but a small battery, or just breaking with warranty service that costs more than half of list price. if anyone could recommend a reliable charger that just gets the job done, i'd appreciate it. i don't plan on leaving the batteries hooked up and will disconnect them no more than 24 hours after they're charged as soon as i see they're ready. i just can't see investing in a $100+ charger as i hope to be running li-pos by summer.

that is the BASIC system, and what i'll be starting with, but it still needs a light show and i've finally found the "perfect tech" to do it. i've always thought about color changing LEDs as ground effects and mounting projectors on towers, but that would look wonky, and the heavy lights would be in a high stress area wobbling at the top of towers with every bump or sidewalk transition etc. and possibly could even cause a self-destructing tip over.

then, just last week, i stumbled upon self contained $10 (or less) 48 LED sound activated sunflower lights like this...
https://www.youtube.com/watch?v=ao_Cj7wivdQ&index=98&list=PLITfP3d88mvYjtG9akbaNsjjxs0r5sclV
the very first video i saw of them BTW

i thought... hmmm... they're cheap, small, sound activated, and do make interesting patterns, but they'd look stupid outside a system and might not project downwards enough for ground effects. a few days went by until it hit me... hide the entire system inside a white (maybe even grey) nylon shell and project patterns from the inside! then, i could have a really nice monolithic looking "slab system" and if i used thin fiberglass, or even carbon fiber strips at 45 degree angles inside along all of the edges, i wouldn't need a heavy and fugly light blocking frame around the displays (top & all 4 sides) but instead might have 1/4 inch or so of shadowing at the edges of the system with the shell's frame ALSO serving as a light blocker so each light's output doesn't spill over onto adjacent sides.

it's a nice elegantly simple solution that will allow me to build "the coolest street party system ever", maybe if not the absolute loudest, but loud enough and then some. no-one has seen a system like this YET. it's neither intended to be an SPL drag racer or an SQ finalist, but merely a good "loud & clear system" people can dance to and that thumps instead of booms. (i'm THINKING of calling it thumper) any car systems i embarrass along the way though are nice little notches in my booty spankin' belt.

• LED sunflower disco light   (Open in New Window)

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Kimber Kable

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