my carbon fiber 3x8" "BIG BAD BUH-BOOM BOX" design

[funktoon]

OK... i took a break from tweaking my Tecsonic J-2 design which i'm going to redo one more time from scratch to fix a few minor issues as well as get a new graphics layer for upcoming color changes, so i've been working on this "from scratch" design that'd be what i'd build for myself if i ever wanted another boombox. some might find its simplicity boring or the yellow over black bumblebee color scheme tacky, but the point was to match the yellow of the planar tweeters better. they serve several purposes... in theory, they're a lot lighter than domes with big heavy magnets, they're efficient and easier on batteries, they're large, so they should move more air than domes, and planars are more hifi sounding as they can extend much higher than regular tweeters with more speed to boot, so everything was built around those.

the carbon fiber box would be both light and extra strong, tri-amping with class D & LiOn batteries would be lighter & more efficient, and the box only has the controls needed with no un-necessary fluff. i like the design after figuring out to color key the graphics to the speakers... it's my kind of minimalist design. the 3 x 8" woofers would be subs only, probably at 20-100Hz with separate amps for the 5 1/4" mids and tweeters. the design is based around HiVi kevlar woofers which have those annoying rear mount gaskets, like PA woofers that no-one ever uses and are an eyesore to me. mounting the cones inside solves that problem as well as allows closer spacing of the mids & tweeters with some overlap. the wider spacing of the subs is to accommodate both the outer rings along with internal bracing to minimize box resonance.

the original plan was to mount extra long ports inside the sides, but if i actually built this box, i'd probably add feet with downward firing ports which should give a slight bass boost.

there's no handle for the box... the best way to carry one this big and heavy with all those big magnet drivers, as far as i'm concerned, is putting a couple guitar strap nuts on the sides on top for shoulder slinging.

whether or not the visuals appeal to you, this would be a serious piece of hi-fi kit... especially with 200w (3dB headroom) for the three subs... probably with extra EQ to make them flatter without the bass boost, 50w each for the mids and 25wpc fo the tweeters. that's a fair amount of power with both an extra woofer and extra large mids and tweeters to move a lot of air. in theory, it should be able to blow any box ever made away for both SQ & SPL.

it'd also be crazy expensive to build, just for the carbon fiber without the added CNC machining, but it'd also be "the best ever", in my opinion... maybe only intimidated by 10" rexels, though i bet those only have 2x50w amps, if that.

whatever you do... don't drool on the new art

 

[floyd]

That looks pretty damn awesome , good job on that design.

 

[Jorge]

Just a thought: how difficult it would be to incorporate cassette mechanism into such beauty? You know, to make it into a "real" bbox, and to build a wall with bumpboxx offerings...
Mechanism scavenged from JVC or National, those seem real nice...
Totally Love the idea of Kevlar drivers, look soo hi-end I want to buy it already!!!

 

[funktoon]

it'd be as easy or difficult as taking the guts out of whatever boombox, but old school runs at 12 volts and class D is happier at 24 or more volts. it'd force compromises in amp choice or having to have both 12v & 24 volt power supplies. the EASY solution would just be using a walkman as your source. that's how you could add a CD player too. if you want to go REAL nuts, you could bring one of these sony portables. i have one for field recording. it sounds pretty darn nice, but is heavy, especially with 2 D cells... but it's a quality source.

the reason i popped in was to share the improved version that gets rid of the plastic tweeter mount and uses dynavox 5 1/2s for midbass. those are some of the sexiest speakers ever as far as i'm concerned, and the giant dust cap ties in with the "big & bad" theme, makes them look more like dome mids, and would better time align with the planars.






let's see if it was just a bad browser window



OK... i guess i was just trying to post it wrong. in the previous version of this reply i couldn't get to post, i was saying sports walkmans are natural choices as external sources for this system



maybe it was the annoying "extend session" popup that seems to cause browser issues here at the library

OK... it was some kind of hacker crap embedded in the sports walkman pic i can't link to, or save & upload either. you can google sports walkmans anyways and probably already know what they look like

 

[floyd]

I like it .
it has an audiophile look about it but cool at the same time.
awesome.

 

[Jorge]

My understanding is that Bumpboxx dudes played the best brains here, then went solo.... I really like what I see here because of its planar tweeters: very forgiving, analog-sounding thingies with the technology really scaling down price-wise from Stax of the 70-ies onto the affordable side for guys on the budget! But not a single bbox with such tweeters, I wonder why this never ever happened?? Too much power draw from batteries?
Now that you mentioned it, Top-loader mechanism looks like an idea for such bbox!

 

[floyd]

With that speaker set up and a few class t amps and a good preamp with planer tweeters and Edge wound Kevlar mids. This f****** thing would smoke a bummboxx into next week .

 

[Superduper]

No CD, no tape, radio, no anything. No handle. At least blimpboxx is real. I don't do fantasy football and I certainly don't do fantasy boombox. Besides, as for the no no no issue, I seen that movie before, and it was a snoozer.

 

[funktoon]

[SIZE=14pt]just a few minor revisions...[/SIZE]

[SIZE=14pt]i beveled the edges... not fun carrying a box with sharp edges that are probably more damage prone too. i didn't do the corners though... maybe in a final version. they were too fiddly to bother with at 4 in the morning.[/SIZE]

[SIZE=14pt]i also need to add feet for the bottom ports and though of adding a hollow aluminum tube rigid handle on top for when straps aren't an option. [/SIZE]

[SIZE=14pt]i dropped the woofers to be able to push the dynavox mids out more, along with the tweeters for the widest stereo image possible[/SIZE]

[SIZE=14pt]seeing i switch to mounting the tweeters inside, there's no reason to keep the old grill style. i REALLY like the look of the simplified tweeter grills. that's been the overall goal of this design... KISS (aka "keep it simple, stupid"). elegant simplicity.[/SIZE]

[SIZE=14pt]if i was building a boombox... this is what it's look like[/SIZE]

[SIZE=14pt]back to the cassette deck comment... this is a total new jack design. i don't think kevlar woofers came out 'til the 90s, and even then, only B&W had them. planar tweeters weren't around 'til this century. RTAs existed back then, but pretty much only on studio gear, and even then, weren't common. carbon fiber wasn't a thing yet. it started getting popular in the late 90s with custom car parts. finally, class D amps weren't available until around 2005. [/SIZE]

[SIZE=14pt]adding a cassette deck would also be a bad idea for a couple more reasons... this thing'd weight a ton with 10 pounds or more worth of magnets and all those big unshielded magnets would be very bad for cassettes. a walkman & a cable would be best in my opinion. besides, there isn't any room for a deck. if you want cassettes, check my Tecsonic J2 redesigns out. obe could be built with prototyping & CNC gear along with a few thousands of dollars.[/SIZE]

[SIZE=14pt]if you want to be thematically correct, you'd use a PMP with it, not a lowfi cassette that'd hiss like crazy with the extended highs from class D & planars. besides, PMPs hold way more music, can be way more hifi than cassettes, and come in very warm & analogue sounding flavors. that was what i designed the box for... and no blue tooth either, though it's easy to add blue tooth to ANY boombox these days... just mount a receiver inside & wire & power it up.[/SIZE]

[SIZE=14pt]fanally, here's a better look at those gorgeous dynavox 5.5s. those are some huge & heavy magnets! imagine this box with an A/C transformer, discrete electronics, mechanicals, class A/B amps with heatsinks, and a dozen D cells![/SIZE]

[SIZE=14pt]the box could be re-done with 6 1/2" mids to move more midbass air, but they'd force the box to be taller which doesn't look right & would have slightly sloppier mids than the 5.5s. besides, they look "just right" next to the planars. i just love the looks of the L/R speakers. accuton makes some gorgeous 8" white honeycomb dome woofers, but they look like they weigh 50 pounds each. that, & they're $900 each, but they'd look awesome in a pair of mini towers, no?[/SIZE]


[SIZE=14pt]as to WHY no-one's ever used planars... they're expensive. those tianles are about $50 a pop. heck, a LOT boxes FAKE their tweeters, and even ones that have them always used cheap cones. i always wondered why boxes didn't have cheap but light piezos... they wouldn't even need crossovers... just a cap & a resistor.[/SIZE]

[SIZE=14pt]if i had the money, i'd BUILD this box. it'd cost at least $1000 between parts, batterie$, carbon fiber & CNC machining even if all of the internal bracing was cheap fiberglass.[/SIZE]

 

[Reli]

Actually a lot of vintage boxes had piezo tweeters......I'd say at least 25-30% of them did.

But it was usually the cheap crap boxes that did. So the piezos were cheap crap that you'd find in a Hallmark talking greeting card. And often they don't work anymore. Which means either they just stopped working, or their frequencies are too high for me to hear. I can only hear up to about 14K, because I've played with too many guns and fireworks and headphones.

 

[funktoon]

well, both my lasonic & yamaha had fake tweeters. piezos are better than nothing. if manufacturers used "standard" piezos, one could just unscrew one from a $2 horn and pop it in the boombox. i dreamed of hotrodding my lasonic with "real" woofers and putting soft domes in place of the cone tweets. to me, cone tweeters are the lowest of the low.

 

[Reli]

Usually a boombox piezo is just a gold dime-sized disk with a wire hooked up to it. And glued down against the case. No screws or anything. You'd probably destroy it taking it out, lol.

 

[Jorge]

If I may ask: what is Soft Dome vs Cone tweeters? Silk vs titanium?
I also noticed that piezos do not have even a cap for a x-over, why is that?

 

[Reli]

"Soft dome" tweeters are usually made of silk or some other fabric like that. Shaped like a dome, i.e. an inverted cone.

Some people say they sound more refined and less harsh than cone tweeters. That's all I know.

 

[floyd]

A piezo electric tweeter is a metal disc with a crystal attached and the Crystal resonates sound when electrical current is applied ,the disc merely acts as a radiator for the sound coming from the crystal.

 

[jimmyjimmy19702010]

Carbon fibre would be light and super strong - all true but it’s completely unsuitable for this application if sound quality is part of the brief. You need mass and plenty of it to absorb the vibes all of these speakers are going to want to transmit to the world via the box casing.

You also don’t need huge RMS power - 20 watts RMS per channel is plenty if you utlilise very sensitive 4 ohm drivers and tweeters.

Comparing your average 15 volt vintage boombox output power to a 12v 20 watts per channel project box is like comparing a 4 cylinder Toyota Camry with a blown Corvette!!

Anyway, enough of this highly detailed fantasy box stuff. Build something for real!!

 

[funktoon]

Anyway, enough of this highly detailed fantasy box stuff. Build something for real!!

my "beatmobile" is very real. there's no point in in putting v2.0 together at the moment as it rains all the time here now. there's a thunderstorm outside right now in fact. that, and i'm just scraping by in one of the WORST job markets in the country. i'm talking FIVE YEARS of applications & resumes and less than a dozen interviews. the only job i was offered was one i couldn't do after 4 days of training.

i wouldn't just build this box. i have a TON of, probably sony, lightweight 5 inch boombox woofers in storage in another state (eating $70 a month out of my income by now) i wanted to turn into a "sweet sixteen x 2" super giant open back system.

as to carbon fiber resonance... of course it's not going to be as good as 3/4" mdf or thick aluminum etc., but this is a BOOMBOX, and several mm thick carbon fiber is going to be way less resonant than 2mm, if that, thick soft plastic. i took resonance into account in my design which doesn't show the internal bracing & fiberglass re-enforcements i'd add.

besides, resonance is much less of an issue with ported speakers. i'm surprised that my super light plastic JBL northridge IIs don't sound boxy at all, at least at low volumes nearfield. you don't have to lecture me on resonance... i DESPISE it! i'm an acoustic suspension guy since around 1985. i hate port resonance, box resonance & driver resonance. making the box ported is a compromise for the small internal volume, but it would lower box resonances.

i've had mission M71s & especially my energy RC10s that had much better drivers than my NHT superzeroes, but hated both. plug their distortion holes, and they sounded like cereal boxes. unplug them, and they didn't sound boxy, but their bloated sluggish bass drove me nuts. overall, i'd rather have "inferior" superzeros because they have rock solid cabinets and their sins are all subtractive. i love them precisely because they DON'T resonate. carbon fiber panels without bracing was never an option in my design. bracing can be almost as good as mass and mass is the last thing one wants in a boombox, especially a big one with real magnets.

as to "cone tweeters"... they're basically just really small SPEAKERs... 2-3" woofers essentially. they're big & heavy compared to smaller & lighter domes which makes them less extended in the highs. that's why ribbons, planars & MMTs extend to 30kHz or higher... their drivers are super light. mass, in drivers, makes it harder for them to stop and start. which is easier to wave... a marble or a sledgehammer?

anyways, haters aside, here's the "final revision" of the box where i added feet and a fixed handle. for me, i'd drop the handle because guitar straps are so much better and carrying a heavy box would throw my back out. heck, even carrying a 12 pack of soda to the counter makes my back act up. i'm an amputee and ALWAYS carry 10 more pounds on my right side, so i carry anything heavy in a gym bag slung to my stump side.

because i can't afford to build a box, i can dream, and as an artist, i can at least simulate the dream. maybe i might inspire others to "think outside the box" (pun intended) and use my ideas in their designs.

why is so many up in here have problems with others "doing their own thing"?!

they make prozac for that.

you know? i thought i was HELPING here by sharing high quality high resolution boombox themed art! if you haven't noticed... 99% of the pics of boomboxes out there SUCK! i wouldn't have to "roll my own" maybe if collectors learned how to use a freakin' camera! as far as i'm concerned, my art's better than "your" lousy pics (though there might be quality pics here and there i can't find with search engines) and i'm trying to do y'all (ingrates & trolls included) a favor and something DIFFERENT to look at than another me too pic of a stock (boring) boombox.

if there was a decent pic of a JVC M90 online, i'd likely never even bothered joining... as un effing welcome as so many trolls up in here make me feel.

BTW... v2.0 of beatmobile will be function only. i already have a down & dirty 1.0 setup without the sub, but it has no bass. v.3.0 will feature an internal sound controlled RGB (i despise that color combo! if i can, i'll pull all the red LEDs & swap purple) LED light show. again... if i had the money... i'd drop everything and build a fiberglass box with 4 x 12" high efficiency woofers & quality PA tweeters, like ciare mini horns.

carbon fiber ISN'T as bad a building block for a box as you think BTW. people have been building un-re-enforced fiberglass sub boxes for decades by now. aside from price, the difference between carbon fiber & fiberglass is that fiberglass is LESS rigid. i'd think carbon fiber is an improvement structurally, unless you drop it hard.

 

[jimmyjimmy19702010]

Didn’t want to upset you. Sorry to hear of your employment issues. It must be frustrating to have all of these ideas you can’t action due to $$$s or lack thereof.

Good luck,

James....

 

[funktoon]

thank you, and YES.... you have no idea just how frustrating it is. my plan was to get a job, save up a year, then move. that was over 5 years ago. i hate almost everything about this place, but mostly the lack of jobs, psycho cat killer & psycho aggressive drivers who DON'T agree with pedestrians having the right of way.

i also have a chip on my shoulder over "locals only trolls" who get their panties in a bunch when i share my opinion of just how tacky & fugly post japanese boomboxes are, yet they feel free to take that opinion i'm entitled to and then use it as an excuse to talk trash about me personally, which i've noticed, in OTHER forums is usually moderator endorsed which drives me into a "you're lucky you're on the other side of this screen you troll f###s!" rage. i don't even take criticism of MY OWN designs (which, unlike snowflake trolls, i have an actual vested personal interest in) personally and refuse to walk on eggshells around others who can't do the same regarding INANIMATE OBJECTS... so, yeah... i'm a bit jumpy as trolls have already taken a few "test bites". i apologize for reading a tone you didn't intend into your comment.

i really DO want to contribute here, although i'm far from an expert on this subject, and tend to go out of my way to help others whenever i can as long as they haven't acted hostile.

i'm on top of finances though. i'm using the "extra money" i made training for a job i couldn't do to invest in a humble ebay biz to make some extra money on my own terms until returning to slogging for a job. THAT's frustrating too... having college training and being turned down for freakin' cafeteria & grocery store etc. work. going to burger king is like a vacation for me. LOL

with that out of the way, i was just popping by to post the front baffle bracing scheme i came up with. while i'm not a boombox expert, i have a fairly decent grasp of basic acoustics & engineering. note how i tried to minimize the surface area that could potentially resonate whilst keeping weight ALMOST to a minimum. (drilled out braces would be even lighter) in thinking about the design and someone's comment about mass loading (yeah... i lean towards that too and would NEVER buy a rega turntable or speakers that fail the knuckle test LOL), i neglected to point out that the drivers themselves provide mass loading that would help dampen resonances provided the front baffle is rigid enough, and i think with that much 90 degree bracing... the front baffle should be easily strong enough to stand, maybe even jump on and would be way more rigid than soft plastics. ever pick a carbon fiber bike up?

if, down the road, my other biz takes off, i would revisit this design and produce it commercially, though it would be for a very small niche market due to the high cost of carbon fiber & LiOn batteries. I'm sure a FEW people with the means would love to own the "highest fidelity boombox ever made". the design combines my love for boomboxes as TOOLS to fight the evils of evil music (heavy metal, gansta, industrial etc.) & UNITE people from all cultures with positive & upbeat (read REAL hip-hop) dance music. we were all getting along in the 80s and hip-hop was a part of that. combine that with my love for high fidelity, & my love of design & engineering, and THAT's why i made this. it isn't for everyone here, and that's fine... but i'll bet a nickel i'm not the only one here who buys copies of absolute sound or stereophile and reads reviews for gear i'll never be able to afford. the same goes for magazines like road & track etc. just because the box doesn't exist yet and s unobtanium doesn't mean some might find it an interesting break from consumer grade off the shelf gear.

i bring engineering and hopefully a different flavor entertainment here even if boomboxes are "tools of war" for me.