Aurélien Gâteau

Bluetooth Speaker - Part 3 - Using an existing Bluetooth speaker

written on Monday, January 13, 2020

This article is part of a series on creating a Bluetooth speaker from an old vacuum tube radio and spare parts I had lying around in the house.

So after the failure of part 2, I decided to try a seemingly safer approach: buy a small Bluetooth speaker, tear it down and use its guts to power my radio.

I bought a small portable Grundig GSB 710 Bluetooth speaker. It's a mono speaker, but since the radio I am working was also mono, as was common by the time it was created, it felt like a good fit. I checked it worked and started to tear it down:

  • Opening the box
  • Main circuit is out, unplugged from its speaker
  • Control board removed
  • Soldering wires to the ribbon cable, ghetto-style, because I didn't have any connector handy
  • Covering the mess with thermoretractable tube

While rummaging through the basement I found another treasure left by the previous house owner: an old mono speaker.

  • The speaker
  • The box says it's 15 W RMS, 4 Ohms. Sounds good

After checking it worked, I decided to use it for the radio. That meant tearing it down as well and creating a chassis for it:

  • That front plate is a bit rusty
  • Back view
  • I had to break the front plate to get the speakers out without damaging any component
  • All parts of the chassis have been cut
  • Let the glue dry
  • You never have too many clamps
  • Installing the speakers in their new home
  • All connected
  • Looks good enough, especially since it will be covered eventually
  • Checking the chassis fits correctly in the original case

It was time to test... We used the radio to play music during Christmas Eve. It was working well, but after pausing the music during the meal, we were unable to turn it back on. Damn.

The next day it was back to normal. I suspect there is a power-saving feature in the GSB 710. I spent a few hours trying to figure out how to bring the amplifier back from that state, without success...

This meant I am almost back to square 1: the chassis and the speaker I can keep, but I need to find yet another replacement for the Bluetooth amplifier.

After some more research I found this website: the Radio Workshop. Ray, the workshop owner, is clearly a passionate. He prefers bringing back the original electronics to life, but he actually supports adding Bluetooth to beyond repair radios, and even produced an eBook explaining how he does so. I bought the eBook, ordered the components, and now I am waiting for them to all arrive.

Next part will be about some work I did on the front-side, waiting for the required components to arrive.

This post was tagged bluetooth, diy and speaker
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