Bang & Olufsen 900k Boombox





Introduction: Bang & Olufsen 900k Boombox

This is a conversion of a B&O; radio/amplifier from ca 1964 to a portable, battery powered boombox for stylish picnics in the park!

Step 1: The Beginning

I was given an old B&O; stereo radio and decided to do something interesting with it. Here are the main parts that I used in the project.

Step 2: Gutting It!

Time to look inside and start to remove the old electronics.

Step 3: New Base

I had to have something in the bottom of the box to put the battery on so I made a baseplate of a piece of aluminium.

Step 4: Baseplate in Place, Electronics Removed

I kept some of the PCB so I could keep the frontpanel buttons, one is used for power on/off.
This is the a test with the battery and charger to se if there is enough room for everything.

Step 5: Battery Retaining

I put in some screws and nuts to stop the battery from sliding around.

Step 6: Installing the Amplifier

I needed a way to mount the amplifier on top of the battery so I used some scrap aluminium bent in an L-shape.

Step 7: Amplifier in Place

I managed to fit the amplifier just below the wire for the original tuning indicator for the radio, it looks nice if the tuning control is turnable even if it doesnt actulally do anything!

Step 8: Time to Do Some Wiring

Added a pair of goldplated RCA-jacks to be used as input/output to the amp if i want to use external equipment or connect it to a bigger setup (or subwoofer) and also wired up the old speaker jacks if i find some matching speakers someday.

Step 9: Lights!

I wanted the machine to show power on and also look like it originally did so I added some PCB's with green LEDs to illuminate the fron, "Stereo"-indicator and signal strenght meter.
I also changed the old and noisy volumepotentiometer to a new one from ALPS.

Step 10: Time to Work on the Case

I wanted to change as little as possible but a real boombox needs a carrying handle!
I found a nice aluminium handle on an old Compaq server.

Step 11: Support

Since the case wasn't designed to be carried I had to reinforce the thin wood with some sheetmetal to make it take the weight of the electronics and battery.

Step 12: Almost...

I tested it but noticed that the 40+ years old speakers wasn't quite up to it...
I went out and bought a pair of modern coaxial carspeakers instead. They were a bit deeper so I made some spacers of MDF-board.

Step 13: Feet

I put on some new rubber feet, the old ones disintegrated when I tried to clean them...

Step 14: First Test

Here is pictures of the first test-run with everything in place, it works!

Step 15: Finished!

It turned out great, good sound, pretty loud but a bit heavy.
Expected batterylife should be around 14 hours at medium volume, I'll test it and post the result.


Step 16: Scrap..

This is what's left after the build...



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    We have a be nice policy.
    Please be positive and constructive.




    Your new creation is of good use now.
    My turn table (BEOGRAM 1203, Type 5239) stylus is broken. I couldn't find a replacement needle, B&O nolonger makes them. Could you please search the possilbility of finding one for me in Sweden?
    Head number is SP10. My E-mail:
    Best regards

    That looked like a nice tube multi band radio......... until you wrecked it : (

    1 reply

    I'm not a barbarian guys! This one was an all transistor (germanium propably) radio with NO TUBES and it was already heavily corroded due to moisture in the air and had a broken power supply. The things that looked like tubes was propably just the old leaky electrolytic capacitors in the supply. Here in Sweden you can find them free at the recycling station or at flea markets for less than 50Euro. One of my friend found a complete Beosystem 6500 with the big remote in his appartment building trash last week...that is a good find! It is going to be restored to original condition.

    Hacking a late 60's radio. OMG... a mod mod. Good choice too, as those B&O; 900's aren't worth much more than about 50 Euro or so.

    1 reply

    Hey, if anyone knows where I can get one for 50 Euros let me know, will you? I just got whipped in an Ebay bidding war on one of these. Of course, I would restore it rather than gutting it. I like the idea of re-purposing, but I like vintage Hi-fi better. ;)

    Was this tube state or solid state? I think I see some vacuum tubes in the last picture in the pile of junk :-(.

    Do you realised that you torn apart and destroyed what is possibly a valuable radio? Not to mention B&O; is top quality gear!

    1 reply

    Nice work, it's cool to hack old stuff like that. I just finished a hack of my own installing some new woofers in some Beovox S55s, but soon I'll be swapping the turntable of my beocenter 7700 with a small laptop. I'm going to try to keep it looking B&O; though. ;) Anyway, good job! Looks pimp!

    1 reply

    Thanks! I have since added a remotecontrol for my Samsung MP3-player. The original B&O; buttons controls the MP3-player, it was just a matter of finding the right resistor values for the different functions of the player and then have the buttons switch in and out the resistors. Be sure to post an instructable or some pictures of your projects for us to looka at!

    wher did you get the parts, power supply, amp, etc.

    1 reply

    Hi, I found all components exept the speakers in my scrapheap. I can hardly throw away anything and as long as I have space left I continue to save good stuff...makes quite a mess but I can build most things without buying anything.

    bean_machine: Yes I did, im Swedish and I used our spelling...i'll correct it!

    it's cool, but me thinks you spelled picnics wrong the the intro


    This is way cool.

    That is just gorgeous. Beautiful repurposing!

    Thanks! The volumecontrol wasn't only corroded, it was reverse log with several taps...totaly useless as an ordinary volumecontrol.

    very nice! for anyone that has an old radio with a noisy volume control you can reduce the noise by firstly switching the power off, then spend about 5 minutes turning the control from min to max. That will clean off most dust or corrosion.