Well it was that time of the year when the weather was nice and people go out for a barbeque. But I was always missing the decent sound out there in the green. So there it was, the idea of a beatbox that can kick some serious sound and move some air. But i was looking long for a decent case and was considering building my own form scratch, but than I found one with a whole lot more personality to it. An old Grundig Bandmaschine (reel to reel deck), made out of wood with a nice classic look to it. That's when things started to take shape. Well now it features a 4X150Watts car-amp with 2 attachable Subwoofers and an ATX powersupply.

Step 1: Case Preparation

The old Grundig Bandmaschine TR 40 was still in good shape on the outside, just the mechanics didn't work at all anymore. So no bad feelings for stripping it down. Well in the end I regret throwing away all the buttons, cause I could have used them on the beatbox, but well that happens.
I cut out a 12mm board to house the speekers ( 100mm max 120Watt) and they sit pretty close together but that is necessary, because it is going to be pretty grammed in there. I did cut off some of the the fake leather to make the glue stick better for the board. Glued in the board stiffens the whole case.

Step 2: Power Supply

Between the speakers I glued some wooden pieces to carry the amplifier, but more to that later. As a power supply I used a computer supply. Well I tried one before but it was too weak. Because the amplifier need some 10A on 12Volt I had to get a stronger on.

The powersupply finally used has 300 Watts and pumpes out 15 A on 12 Volt which should give me enough flexibility. Further than that I desoldered a lot of the cables I didn't need. I only need 2 yellow (12Volt) cables, one red ( 5Volt) cable, the green (on/off) and 4 black (ground) cable. It sits at the bottom of the whole case. I turned the airflow the other way (flipping the fan), so it sucks in air through the old bottom connector bracket, which I widened to get onough airflow.

To get the power supply going you have to attach the green cable to a black cable. But often the Powersupply checks if it has a load and will shut off if it notices that there isn't any. So I joined a 5Ohm resistor to the 5Volt cable and a black cable, and the power supply keeps on running. But the resistor get's quite hot so it is joined to the fan outlet to cool it with air. Be extremely carefull when handeling an opened power supply, always disconnect the power cord.

In the corners of the case I glued 4 threaded rods to hold the top piece later on.

Step 3: Amplifier

I ordered a amplifier from ebay pretty cheap. It's aluminum casing was to big for my case so I took it apart and attached some old pentium2 coolers without the fans(cheeap on ebay). The whole assembly sits on a board which I screwed on top of the brackets I installed in the step earlier. To be able to use the volume and bass/treble controls when it is installed in the case, I desoldered the pieces and extended the cables. So I was able to install the the adjusters on the top corner of the case. It was a hell of a mess with some 36 cables.

I will be able to adjust the vol/treble/bass seperate for the two channels in case I only take one subwoofer with me. Installed in the case everything fits just perfect, but it's getting already pretty crammed in there.

Step 4: LED Sign.

Well a decent beatbox definitely needs some light to it. So considering what was given I came up with the idea to install a sign writing on the side of the case, using the already given holes around the case. So when the light is turned off, the writing is not to be seen.
To achive this it was eather using some 120 leds or doing some fibre optics which I could get my hands on. So it was down to the fibre optics. I drilled the holes, a lot ot fhem. Glued in the optics with hotglue (let it cool down a bit on the tip of the hotgluegun, or it will melt your fibre optics) and bundeled them to be lid by 5 leds. I made a special bracket to hold the leds in place.

Step 5: Finishing Touches

Well for the final touches I had to install 2 crossovers. And joined them to the 2 speakon connectors (subwoofer) on the side of the case. Well now it's really full in there, but it still has enough place for airflow (in through the former pc powersupply outlet and out throgh the top where the old speaker used to sit). The other 2 connectors are for being able to run it of an external battery pack (12 Volt 18Ah) which you get from car jumpstarter. I also put 2 chinch connectors to the front to be able to attach a mp3 player. The player and the cable tucks away nicely in the in the pocket when closing the lid.

Well and that�´s it. Took me about 4 Month to finish it all together. Hope to give you some inspiration for your projects. Some more stuff on my side, that still needs documentation:
My hack page.
wow...i love this the leds are nice where did you get the fiber cord thingys?
I'm so jealous of the Grundig what a find. Great project very elaborate but fairly simple. Two thumbs up!
Question... since these speaker drivers are so close together, would it have been easier to wire this up in mono (or, joint stereo, actually). It seems like it would have saved using one of your two crossovers...
Well it would have savend me one crossover true. But i wanted to be able to adjust volume and bass and treble seperately on the two stereo lines, because if i only take one subwoofer with me i can take one line ( the one with the sub) all the way up to eleven, and just take the bass off the other and crank it up as well.
I really want to make one of these, but I can't find one of those Grundig Bandmaschines.
I found one on ebay germany <br/><a rel="nofollow" href="http://cgi.ebay.de/TK-40-TOP-Zustand-1961-GRUNDIG-TK-40-1a_W0QQitemZ230148639524QQihZ013QQcategoryZ30930QQssPageNameZWDVWQQrdZ1QQcmdZViewItem">gundig tk 40 ebay</a><br/>but I don't know if you will find one in the US. But maybe you can get something simular from a similar make like the Akai Cross-Field Head X-360D, looks different but might be quite nice as well, as seems to have similar dimensions<br/>
Thank you for your response, perhaps you can also suggest some nice speakers to use with this creation?
Well if you take a car amp you need 4ohm speakers. So take some car speakers. I would prefer one way speakers, although mine are 2 way speakers. and you have to consider how much space you have in the case. in mine there are only 2 or 3 mm between the amp carrying board and the speakers. and than just take the best your budget has to offer, will lots of db.
Thanks buddy, using this casing, suggest actual speakers available on the net?
www.partsexpress.com great prices on speaker drivers.
Sorry been busy on my diploma. Well mine are Blaupunkt speakers, but they are a bit weak. I don't know what other speakers to use, sorry. But Oimi sent me some pix of your progress maybe I can give you some more tips if you want.
this is my favorite instructable so far. but i have 1 simple question. where did u get your fiber optics from and how much was the cost
hi there! Well I got mine from a old project at school, leftover and broken ones. But you really don't need many. I would guess all together about 5 meters. But you get them off those cheap hand light flower things. You get them cheap in any toy shop I guess. I have no idea where you can get just fibre optics, sorry.
Pretty decent man, but why use the tweeters? Those are midranges at the most, they're prolly 120 watts because they were most likely made for the midrange section for some sort of tower speaker. I would have stuck with like two 6-7inch woofers and a couple tiny tweeters.
well the amp has 4x150Watts and so i needed 4 the same speakers. they are actually blaupunkt car speakers rated at 4OHM, they are only some 50mm deep so they fit in behind the amp. And I wanted it to be really loud if I need it for a party or so, that´s why the subs are attachable.
Well they don't have to be THE same, you could easily run just 2 speakers that are 75 watts and a couple tweeters. What do you need subs for? If it's a party, use your house speakers man. Sheesh, I have a set of technics tower speakers and a mirage sub, you can hear it clear as a bell outside.
If you consider outside only your garden than your right. I consider outside the park, the lake and a festival. You can run it on the battery pack or even hook it up to your car cigarett lighter. Also it didn´t cost as much as some techincs speaker, which I own as well.
Actually, I had it playing this morning. Here's what was going, I had some random peter gab song playing, turned the volume up to -2db (theres only two more volume notches up to full), went outside, stood at the FRONT of the house (my room is at the back). All I did was twitch and then ran in the house before I got in shit, I could hear it clearrrrr as day, I didn't even go into my back yard for fear of the neighbour coming out.
Yea you're right, but we've all got our opinions :p
wow!!! mean!!! this is amaizing... i'm shure you know a lot of electronic stuff hehe!!! real cool!!!.. i like the fiber optic effect!!! is cool!!! keep going!!!
well actually I don't know all that much, just what a resistor does that's about it. All the other stuff is basically just putting + to + and - to - and some trial and error I guess.
I know this guye personally!!
hey, lets go to the gym. sems like you need it!!
in the internet there is a place for every freak!
He, yeah ich kenn den persönlich!!!!
wow. that is so cool. i would never be able to keep track of all of those wires. how long did that take?
well it took about 4 month all together but just minor work the last 2 month, but I guess if you have some time to spare you can get there in 2 weeks, without all the trial and error I went through (I blew 1 psu and 2 amplifiers and a bluetooth modul, still trying to get one working)
This thing is awesome! You did a great job just fitting all the components inside of the case and building a versatile portable amp/sound system. Then, adding in the fiber optics and optional sub outputs really just takes this thing over the top. I really like the look it has and the low/hi tech mashup. The other projects on your site look pretty sweet too. Your handle bar bike carrier bag looks a lot like the waterproof sacks that sit on the middle tubes of white water rafts - they share almost the same fold & close design. I would love to see some more of your projects and let me know if there is anything we can do to help you out.
thanks noahw I will not have any time soon for the other projects but i´ll definetly post them some day.
F*cking awesome! I personaly would have used the leds or anothr fan instead of the 5ohm resistor (or something bigger like 10k so it wouldn't get hot;) but I supose it depends on what you have laying around and maybe you need a sizeable load to keep it on. I personaly have a couple dozen AT powersuplies (the old kind that turn on with a reguar DPDT switch) so I haven't actualy had to gut an ATX supply. That thing is very sweet; better then what you could buy and even cooler because of the retro case you put it in. BTW: I'm quite sure by "frequency splitter" you mean a crossover though your term is actually much more descriptive of what it does.
Thanks for the crossover tip. And also thanks for the tip with the leds I might get me some other resistors so i can run them on 5Volt and not on the 12Volt where they are now attached. So i can get rid of that 5Ohm resistor.
Wow man, nice job! I remember when I was in 7th grade I made an amp in a lunchbox, which was pretty cool, but not as cool as this!
wow, really nice job. I actually have something similar to this in the works, i haven't documented it too good so far but this makes me resolve to make amends to that. It does sometimes feel bad to gut nice old things like this, but i just gutted an old professional video recorder and got a really nice haul: case for a htpc, 6 solenoids, 4 different motors (one with speed tracking!) and countless sensors. props!
This is really slick.
That is really cool. Great instructable!

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Bio: The ideas that wake me up at night make me want to sleep all day
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