The Boominator - another stab at the ultimate party machine

good God. that is a serious thing. hi there, ive been working on a technically inferior version of the same idea for a long time now. inferior because basically i dont have a clue what im doing, i just wanted a really loud ghettoblaster. heres mine

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


its got an amp32 from a very king guy at 41hz, 2 p-audio sn8mb woofers, and morel tweeters. i dunno much about building a crossover but i bought a few off ebay and found the sansui two ways that im using sound real sweet. i was aiming for a weight of 8kg, i can carry that all day, but it ended up being 10kg, still pretty portable over medium distances.

id love your know how! aggh, really i would. id say yours would eat mine for breakfast. those fuel cells sound interesting, do they come in a reasonablly sized 12v or 24v form?

cheers,
ned .
 
I would like to make something similar if you don't mind.
Two questions:
Did you wire 2 woofers and 2 tweeters in series-parallel on each channel to keep impedance up?
Aren't you worried that amp clipping will wreck the speakers?
thanks
Paul
PS What's happened to the 41HZ shop?
 
Sorry for the long silence.

NED209, excellent work! reminds me of the first boombox build I did which also was refurbishing an old 80s style boombox with new drivers and a new amp. Currently, I'm mostly inclined to ditch the fuel cell idea. Simply to much hassle but if you're interested, visit www.ird.dk

coit, aboslutely no problem. You should note that I plan to sell these at some point in the future but for your own use there's absolutely no problem in building your own. You should note that this is the final prototype version and that the real full version will have slightly different dimensions as I'm putting in a 14 watts a-Si solar panel to cover the entire top. I'm also using another tweeter now instead of the peizo type in the prototype.

This one: http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=270-049

That also means that I'm using a proper filter now. It's just a simple 6/12db octave type so it shouldn't be too difficult sorting out component values. I'm not finished tweaking the filter yet.

As for your questions. No, I wire the driver pairs in parallel to lower the impedance to roughly 4 Ohms to draw maximum power from the amps. And I'm not at all worried about wrecking the drivers, they are professinal types that are rated at 20 times the maximum power the currently recieve.

The www.41hz.com shop and forum should be up and running now.
 
Hey Saturnus, cool posts!

I wondered about the piezo drivers before, because I never find they sound very nice and the limiting factor is mostly the bass/mid driver regarding efficiency. So it must have been the sturdyness and simple filter technique that drove you to use them. I think the soundquality will be much better with your new choice.

Saturnus said:
And I'm not at all worried about wrecking the drivers, they are professinal types that are rated at 20 times the maximum power the currently recieve.


Be carfull with clipping behavior of the amp though, some noobs (that read you post) don't know about this danger. Clipping is much like DC and DC keeps the speaker cone in a fixed position for too long. This stands in the way for the coil to cool because there's no/hardly movement/no airflow.

Please show some pics as soon as you have built something and have the time, thanks!

Keep up the good work!
 
hey thanks Saturnus, id love to see both your new one and the first refurb you did of the 80s boombox. im addicted to them, have been for years.

following V-bros advice im going to build one from scratch, though im essentially building a wooden replica of an existing model, this one

the big one -

An externally hosted image should be here but it was not working when we last tested it.


weight is critical to me. cant stress that enough. the whole thing has to be as close to 8kg as i can get it. (i dont have a car!) so the amp32 and 41hz series are a real blessing for me. i bought the killer drivers for this project, 1.5kg and 99db, im in love. - http://www.musicgear4u.com/bass-guitar/bass-accessories/celestion-bl10150-neo.html

so id like advice, on what type of wood to go for? probably plywood ill go for, im tempted to go as thin as possible, quarter inch, and brace it. but im open to advice or suggestions. the bbx is huge, id say about 36lt.

heres a pic of the previous radio at night, i got all car hi-fi on it, and sanded down the fins on the p-audios for a more dramatic effect http://i8.tinypic.com/6z6ckfr.jpg

Saturnus i hope i havnt hi-jacked this thread, i was a bit nervous of starting a new one!
 
mmm, the more i read the more im thinkin that. but 3/4 inch would be insanely heavy at that size, not portable at all. i like the Benosonic :) mine will be more realistic. im going to strip the adornments from the original blaster (chrome, stickers ect.) and affix them to the new box. should look exactly like the original with enough coats of black gloss.
 
diyAudio Editor
Joined 2001
Paid Member
Seems that some sort of high tech sandwich material would be best.
Like epoxy and carbon fiber/glass skin with foam or hexagonal cell or balsa core. Not cheap but I'll bet you can get sheets of stuff like that somewhere.. maybe 1/2" thick. Boats and airplanes use it.. Celestion used the stuff with metal skin for the SL6 speakers I believe..

Like here,

http://www.acp-composites.com/acp-lp.htm

or here,

http://www.cstsales.com/fiberglass_sandwich_panel.html


ooooh too pricey :(
 
I use 12mm 7 ply birch plywood. It's lighter and more rigid than any other kind of wood you can get. I the mark II version I've also experimented with cutting some weight while maintain the properties of the plywood, mainly because as I want to start selling them online the weight has to be under 25kg or the price for international shipping goes through the roof. So with a heavier tweeter and much larger (and heavier) solarpanel I had to find a way to cut some weight.

I achieved that by routing 4mm deep 16mm wide grooves with a spacing between the grooves of at least 12mm into the 12mm board. Note that the mark II version still only exist as a 3D model but the modelling program (CATIA) is usually pretty accurate.

I'm not at bothered by the hi-jack. So few people are interested in portable audio here that the 2 main threads about it needs to be bumped from time to time.
 
Oh, and btw, I'm not sure but I think my refurbished 80s boombox has gone to hifi heaven. I gave it to a friend of mine years ago before she moved to the other end of the country. I don't know if she still has it, since she only had to use until she got settled in and bought a decent stereo of her own. Maybe she still has it in her addict?
 
Yes, I have thought about it but came to the same conclusion as Tekko that it would use up power unnescessarily. The only gadget I will include is an round dial analog voltmeter with 8-18 volt read out which would fit all the different types of batteries you could stuff in it, ie SLA, 3 cell LiO and 9 cell NiMH.

That would look extremely cool I think, especially in the design I'd prefer which would be a red "cherry" veneer finish with inlaid "ebony" and "ivory" corner fillings like those on vintage audio and tv equipment.

But when (if there's indeed any customers for it) I start selling it, the customer could order any design they'd like as long as the basic box isn't affected. So if they decided that they would have a multichannel lightshow built in, so be it.
 
DIY Boomboxes

I built something similar in the mid eighties..how nostalgic!
I took a then high tech Pioneer KP-???? AM-FM Cassette mated with a "High power" Pioneer GM-120 amp rated at 60 WPC Peak RMS.
Built a wood box to hold a small 12V tractor battery, mounted the 'deck' vertically, fastened the amp on the back & mounted two Radio Shack Minimus 7s' with the factory brackets.
She was small & the sound was excellent....a few summers I would have her playing while sunbathing at Willamette Park in Portland Oregon....had countless people come up to me wondering what that great sound came from!
____________________________________Rick..............
 
Neon would be cool, but in a portable system wouldn't be very practical. If you kicked the box, dropped it, or hit it against a car door, then you stand a very good chance of breaking that long Neon tubing.

I've closed the car door on my box, hit it against the wall of my house, accidentally kicked the side of it too. I can only imagine what would have happened had I installed a Neon system inside.

I thought about putting lights like a string of LED's or EL-Wire inside mine (and since V-Bro has seen it but most of you haven't - my boom box is encased entrirely in plexiglass)

I was originally going to run it off the amp power supply since the LED's don't draw much. But going from 12v down to the voltage of the LED string or strands of EL Wire pretty much required a separate power souce, which means a separate but smaller battery. Not too bad of a weight penalty, but since I mainly use mine during daylight hours it would be a waste of time and money since no one would see the lights under the sunlight. So thus I scrapped it.

Those two are much more practical in a portable system, but won't be as bright as a Neon system. But they will be easier to deal with since you can bend/wrap the LED string or EL-Wire, not to mention they are a lot cheaper to fix or replace.
 
I often use my small boombox at night by the campfire, so a bit of light prevents it from being kicked all the time, or worse... people tripping over it breaking their necks...

A few leds and some plexi-distribution won't kill your batterypower too much....