Intro: The Amazing Tube Internet Radio
I found an empty radio case from the 30th made from bakelite.
The whole electric was gone and the speaker was totally damaged but the speakers cloth was originally from the 30th as well.
I am still building Volumio based MP3 players and i decided to build a MP3 players with tube amplifier.
Each has its advantages. Volumio and Moode have pre configured radio stations. Moode is able to browse trough multiple USB - Devices. So its up to you to find the playe that fits to your needs.
The players are also able to connect to NAS based music sources. On the first picture you can see the "Wingman" connected to my Raspberry NAS system.
So here are the parts:
- Raspberry Pi
- 2 Gbyte SD - Card for Volumio image (https://volumio.org/)
- USB DAC (KLICK) or similar
- USB to CF adapter (KLICK) or similar
- 32 GByte CF-card
- Tube amplifier kit (KLICK) 4 Watt output
- Audio transformer (KLICK) or similar
- TPLINK mini router (KLICK)
- 5V / 2A Power supply
- Wide range speaker
- Power Switch
- Cables and wires
- Some deco material
A lot of parts I had on hand. You can use an USB-stick for the music as well instead of the CF-card.
BE CAREFULL if you are operationg more the 48V DC this can be very, very dangerous!
So lets go step by step trough the parts....
Step 1: The Raspberry and Amplifier Part
I used an old Raspberry Pi from the 1. generation. It is still powefull enough to run Volumio.
The USB DAC has an stereo output but the amplifier is mono, so I used a resistor network to convert the stereo signal to mono.
The stereo signal goes from the DAC output to the converter and than via the poti to the amplifiers input and from the audio transformer to the speaker.
The TP-Link is connecting the Raspi to world.
Please mention that the Raspi has its own power supply.
Step 2: The Power Supply
This is the dangerous part and a bit tricky.
The circuit is from Elektronik Walter as well.
The mains will be converted to 12V, this voltage ist used for the heating of the tube as well.
The 12V from the primary transformer goes to the secondary wich produces enough voltage to drive the anode current.
The output from the secondary transformer was rectified and filtered. The output voltage is around 200V DC with the amplifier tube connected. The output voltage is nearly ripple free.
The sound is amazing!
Step 3: The Case and the Speaker
After cleaning the case and speaker cloth I used the originally speaker holder to mount the new wide range speaker.
I used a nearly dry sponge to clean the cloth very carefully.
Step 4: First Try
I put everyting together and booted the Raspberry, fired up the amp and there was a sound humming from the speaker. I powered everything down an replaced the shunt by a primary coil of a small transformer.
Power on again and no ripples, no humming!
Step 5: Finishing
This radio has no scale for tuning. So I closed the hole by an ornament made from some brass gears and steel wings. This gives the name for the radio:
The sound is amazing and im using the radio day by day.