Special thanks to Yo-DUH_87, http://www.offbeathosting.com & http://www.hackaday.com/ for providing temporary hosting because of my bandwidth overages. So, the original plan was to replace the speakers in my sony studio headphones because one of the ears broke. Later I lost the backing to one of the ears, making it impossible to attach both speakers onto the headphone’s headband thing. I tried making my own headband, but it really wasn’t successful. So, months later I decided to resume the project and just put everything in a package that I could tote around in my backpack. This is the original boombox. I know that there are no speakers in there. I forgot to take a before picture, so this is the best I could do. It was a pretty good unit, but it was also no longer needed, so I thought I’d make use of it in one way or another. disassembly into 3 main units – the battery storage area (took 6 D type batteries totaling 9v.). The good thing about this unit is that I can also plug my backpack into a wall outlet if my battery ever runs out. Also there was the cd tray, which I will not be using because I’m going to be plugging external audio sources into the amp. some of the screws were really deep in there, so I had to make my own tool (a torx bit, extended) next, I poked the speaker’s grill’s out. One of them didn’t want to come out, and I kinda injured myself doing this. Since I know you guys love injury pictures, here it is. – anyways…. moving on, here is all the insides of what was in the boombox (besides the cd player and tape player). I could always add those on later if I had some need for them, but it would take a lot more space. some pictures I took when sizing up the headphones. In almost the same space I was able to fit 3 inch speaker where 1.25 inch ones had previously been. These also gave some tremendous bass for headphones at a really low power. back on track, I cut one of the grills with a giant scissor (tin snips?). Next, I turned the speaker over and hammered around the edges so that the grill was kind of mashed onto the speaker (but making sure that the cone cleared even when all the bass was on.) Both grills on, I cleaned them up a little bit later to be a little rounder remember this picture? Well, the amp in the middle, was hard wired to the main board thingy. I did the long task of manually checking which wires needed to be connected, and which ones didn’t. Out of the 2 groups of 4 wires, I found out that one of them needed to be shorted for the power to work (because the pow on was on the main pcb.) On the second wire I found out which one was the negative, left and right channel, but for some reason I couldn’t figure out the right way to get stereo off of the female plug thing that I desoldered from the main board. I decided to run the setup off of mono, because quality really didn’t matter – just that it was loud (I’m gong to fix it later anyways). Theres the amp with all the wires connected together I decided to run this off of an airsoft battery (9.6v – will this kill the amp?), and also is a picture of the female headphone jack. I didn’t solder it together yet because one of my friends has my solder. Next I plan on building boxes for my amp and speakers in my backpack.
Sweeet mod so far I just bought one of these so i could listen to music from my bag...didnt buy it from there of course, i ebay'd it and got it shipped from america for about $40. I hope yours turns out nice and loud! They confuse the HELL out of people! They just dont know where the sound is coming from , and nobody suspects a bag!
So I cut the back plate and bought those risers at ace. They didn't have one long enough, so I used 2. The basic idea to the dual power on system was so that I didn't have reach in my backpack to turn the power on and off. I used a spare molex to connect the speakers to the alternate on/off button I have screwed into my backpack. The only problem is that if it accidentally gets switched on while inside the backpack my switch can't override that. I might change that once I figure out a way how. These are the risers I got from ace. I'm not sure why the white stuff formed around the holes when I cut them... maby from the heat the circle saw generated. edit> I think I had the blade on backwards The secondary power on/off button embedded in my backpack.
So I was digging around in the game room and what did I find? A mini subwoofer which I think we got in the early 90s. Its a cambridge soundworks sub that was originally distributed by IBM along with its original pentium machines if I recall, because I found it near one of them. So I took it apart and removed it from its amplifier. I would later learn that the hole I had originally had cut for the boombox speaker was too small by just a bit... so I only had one choice. Cut the hole bigger!!! Here it is, initially installed and screwed into the boombox. So I thought, since the boombox amplifier was a lot different than the subwoofer's original amplifier, I had to find some way to boost the output of the sub. So I slapped a pot onto the smaller speaker's circut. It was too powerful of a potentiometer so I decided to hide it inside the boombox until I figure out what I want to do with it (with no resistance applied in the mean time.)
More pics of the subwoofer after being installed........ I later figured out that the sub was too long for the boombox, and I didn't want to have to go and buy more risers thingys, so I used the tools available to me to fix the problem. So I used the same circle cutter and made an inward slanted cut, it kind of looks like this - |\ It worked out very well, and hugs the subwoofer nicely. Here it is with the back plate screwed back on and the sub sticking out the rear end of the boombox. This shouldn't do anything magnetically because its only sitting next to textbooks. I'm more worried about the speakers getting poked out. The button worked flawlessly. Very easy to use. Project Finished I hope you guys enjoyed this... It sounds spectacular, gets pretty good battery life, and is really loud.... But best of all, it was super cheap to make. Next up, a super compact version of this for my friend's apple ipod.
Edit: I set up a rather quick and dirty mirror for all you rabid hackaday visitors, enjoy http://www.offbeathosting.com/backpack/
Specs? Could you tell me the type of speakers you used and the specs of everything(The voltage, wattage, magnet size and such)? And how did the battery turn out? No shorts? Thanks, Wil
i did a similar project not that long ago, for my physics class, we had to design a circuit (insert modder wheel grinding brain noise) so i decided that since my backpack already had a 12v dc system w/ accessor socket, voltage meter, charging circuits already inside (previous project where i needed a way to charge my cellphone in school due to a bad battery, as well i could charge my laptop since i have the car charger psu for it) so i took my small desktop subwoofer that i had purchased cuase it only cost 20 bucks, and it hit pretty decent for a small sub of its size, i fit it into the back of my backpack, w/ the bass port comming out of the side, i cut a hole in the side of my backpack, and i put an 80mm fan grill to cover it up, and used ducktape and foam to cusion it, once i had that i needed to hack up my sub to run off dc, instead of ac, this was pretty easy as it actually used 12v ac comning from the transformer, so i just cutted the trans, and the diodes used to convert the ac into dc, and wham, it could run easily for 4 hours straight, however i never tried it past that, it might have gone for longer, becuase the voltmeter still read appx 11.5v at the end of a hard day from there i just ran the satelite speakers, since the sub had a built in mini amp for 2 satelite speakers, i ran those to the back of the backpack to kind of stick out.., all in all a very nice job i thought, however the sub took up room needed for all those nerdy text books, so it couldnt stay there for long, but maybe ill work on a new box for it that is sliglty shorter, so the books can still fit cheers
the switch overriding as i read from the beginning i noticed you had a problem with overriding your backpack switch incase it got turned on, so here's a simple scheme if you might need it anymore
hah, thanks for diggin this up from the dead guys . Anyways, I basically killed my amp because I kept poking it with my fingers. It doesn't seem to work any longer. I'm planning a much larger project once I get the funds for it. Check my signature for the other miniature boomboxes I've made. Since this project I've found that its much more convenient to use speaker systems intended for computers, as the audio in is self explanatory, and in many cases, you can figure out voltages, etc from looking at the wall power brick. I'm going to make a smaller one in the mean time with some new tools I've picked up since the last project I've posted on here. I also have been experimenting with different painting techniques and such, nothing I've posted on the internet though. Keep a watch out in a month or so : ).
Sleepyhead: thats a pretty cool switch, thanks. What I wanted to do was override the switch, as in be able to turn it on from 2 locations. Warrior: Thats pretty hardcore! awesome man. Accessory outlets is a great idea. I just added one in my car. Otaku: Lucky for me, the speakers never got poked out. I figured why not save the $5, considering I had 60-70 more of these speakers laying around the house. I bulk ordered them for about $0.30 each off ebay. Jack: A had thrown the box out for this stereo a long while ago. I thought I remembered it being around 50 watts peak. The speakers I used were about 3", at 2w each if I remeber. Not sure about the magnet size. Battery got shorted out once if I remember. After that it worked fine until I fried the amp. I also used to poke it with a screw driver while it was running trying to reach the bass boost button.
I looked on ebay Do you know where I can get some good wholesale speakers? I checked eBay pretty thoroughly and I couldn't see anything like you said you got. I would love to get a big box of small speakers like you did. So many possibilities! Thanks...
Anybody know how to... hook up and AMP to a backpack with 3 speakers installed? not professionaly made i wired it myself but cant figure out how to get an AMP wired up, and these things do confuse the hell out of people.
