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.


/Daniel

Step 16: Scrap..

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