Converting an Old Radio Into a Spotify Streaming Box

This project started about a year ago when I came across an old superhet valve radio on ebay. I didn´t had any useful application in mind when I bought it but as it was really cheap an in good condition I didn´t wasted that much thougths about it.

After some research and a few screws removed I collected some background information on the device I just bought:

Manufacturer: Blaupunkt
Model Name: Roma
Manufacturing Date: Between 1958 and 1959
Technology: Superhet vacuum tube radio

Luckily there was a sheet with the circuit diagram hidden inside the radio.

Before we continue, let´s have some words about safety. Devices like this and in general devices that are plugged into a wall socket, contain high voltages which can easily kill you. These voltages can still be present hours after unplugging it. So please, when working on such devices, make sure to not touch any metal parts and if you do, double check weather it is still energized. Stay safe!

Step 1: Disassembly and Cleaning

As I realized the device I just got my hands on is close to 60 years old (which is far far older than I am) and spent approximately the last ten years in a dark basement it was obvious that I had a lot of work right in front of me.

In the next weeks I completly disassembled the radio, taking out the complete electronics compartment, and every screw I could find. I got rid of every cobweb, a lot of dead spiders and a tremendous amount of dust.

Step 2: Insert Magic Here...

After cleaning all the mechanical parts I started researching about the electronics and inner workings of this radio. The circuit diagram came in pretty handy not only for understanding but also for identifiying potentially broken or worn-out parts.

I decided to replace all electrolytic capacitors and all capacitors made from tar and paper (yes they did it that way back then). Even the preparations where really time consuming as everything was hardwired and directly soldered together. So I went through the complete electronics compartment, searched for capacitor which needed replacement and tried to find them in the circuit diagram to get their value.

I came out of that with a list of about 30 capacitors which I then ordered at farnell/element14 (they where simply the only ones having all needed parts in stock).

After installing all capacitors I was able to listen to radio stations in the UHF-Band.

Step 3: Excurse: Running Spotify Connect on a Raspberry Pi

During my work on the electronics I learned about the the line-in connector of the radio to attach external audio sources. I then decided to add a Spotify Connect receiver using a Raspberry Pi to the radio.

To install Spotify on a Raspberry Pi without a display attached. As there are no officially Spotify builds for Linux on ARM available (only for x86) I use the Exagear emulator from russian company Eltechs which you have to buy a licence for.

I will post an extra Instructable on how to run Spotify connect on a headless Raspberry Pi. But here are some keyfacts:
- Raspberry Pi runs Exagear x86 Emualator

- Emulator runs a Spotify Client on a virtual framebuffer

- Framebuffer is accessible via VNC over Ethernet

For detailed instruction see:

https://www.instructables.com/id/Setup-a-Raspberry...

Step 4: Putting Everything Together

After removing the tremendous amounts of dust and dirt, replacing all the broken capacitors, and adding a new powercord. It was time to put everything together.

I decided to mount the Raspberry Pi in the top left corner, right on a piece of wood that holds the speaker in place.

The powersupply is a standard 5V 3A AC/DC Converter which are available for a few buck on amazon. The power wires are directly soldered to the live side of the power switch.

To improve the sound quality (which is really impressing regarding how old the radio is) I added a Hifiberry DAC which is definitly worth the money.

I also added a Wifi Stick I had lying around so I won´t need an Ethernet cable.

Step 5: Connecting the Audio Lines

Connecting the Hifiberry to the radio is quite simple. The radio features a Audio Input which is basically compatible with standard audio output.

As the radio only has one mono channel you have to mix the stereo signal from the Pi with a resistor as shown in the picture.

I simply cut an old 3.5mm audio cable in half, added the required resistor and wrapped everything in heatshrink. After that I soldered the two loose ends directly to the back of the tape jack.

Step 6: Up and Running

It works!

Quick demo of the complete System, first you can hear a local radio station, then I switch to Spotify. It felt kinda weird to play music that is older than me on a device older than the music.

Total time from getting the radio to finishing this instructable was about a year. At first I did not have the Hifiberry installed but the sound quality was quite unsatisfying.

Comments

[augustoalcalde]

Try Volumio, is free and Spotify run as an add-on . https://volumio.org/

[TheBeardedWonder]

Can't specifically say I made it as mine is similar running Pandora rather than Spotify. While I did leave some of the tubes in place most of the receiver components were removed by me since the Radio wasn't operable and I did not have a schematic for the radio until after the project. Great build and kudos to you for bringing the radio back to life.

My build: https://www.instructables.com/member/TheBeardedWon...

[pdavis19]

I tried posting this, but it doesn't look like it posted.

Vacuum tube amplifiers and radios can contain DEADLY voltages, easily in excess of 200V and probably in excess of 300V, at currents that can kill! You should have a very visible warning on this at the beginning of your tutorial (cool idea, by the way). You should give safe instructions for how to discharge the electrolytic filter caps. If the radio is turned on and then unplugged and disassembled, it's very possible for the filter caps to still contain enough power to kill. They might not. Sometimes they put bleeder resistors on the caps for this very reason, but usually they don't.

I build vacuum tube amps. They can be extraordinarily dangerous if you don't know what you're doing. I don't even work on them unless someone else is around. It would be a tragedy if someone got themselves killed opening up a tube radio and touching the wrong thing.

[pdavis19]

One final note on this topic, just to hammer the point home. A friend of mine is an amp tech. He posts some of his work on Facebook. I just came across this post on an amp he's servicing:

"Note to those playing the home game: this amp hasn't been used in months and the caps had 430VDC on them. Always always check."

So, to sum up: Always, always check!

[yrralguthrie]

Do you have to have someone help you cross a street?

I have an aluminum garage door with a sign on it that reads, "Do not hit your head here as you could be injured". Honestly I do.

Pretty soon all exterior household doors are going to have warnings about going outside. (bugs, insects, steps, allergies etc.) That will no doubt lead to signs on the outside warning about going inside.

[brian32768]

I had a good friend die who got careless working on a guitar amp. Do I need to say more? That's "he died" as in "dead" at age 30. Left behind a widow. Please learn the safety protocols and practice them even if you think they are stupid and don't apply to you.

[pdavis19]

Not entirely sure I understand whatever it is you were trying to say, but I think I roughly got the point.

Most of the people on this site have never seen a vacuum tube and the vast majority have no idea that they could die if they touch the electrolytic capacitor in one that's been turned off.

Just trying to share some basic safety information. I'm not sure why you'd have a problem with that.

[Cliffystones]

I've worked with tube circuitry myself since the early 1970s. A few years back I decided to pretty much dump all the solid-state, board-swapping nonsense and re-discovered tubes (Thanks to Diyaudioprojects.com). I completely agree with your initial post. A stern warning for anyone not familiar with these circuits is a kindness, and quite possibly a life saver, NOT (like the example used above) simply a legal disclaimer. Folks like "yrrlguthrie" need to try putting their fingers across one of those charged caps, then they can pop-off! At bare minimum, several hundred DC volts ripping up your arm is a very painful way to discover hitherto unspoken swear words. When I'm doing a build I can count on at least a couple of those enlightening experiences :(. And that's mostly due to being an "old-timer" who has become too comfortable around the things. So when in the unlikely event I do electrocute myself I'll only have my own sorry ar$e to blame :).

[PascalK2]

I guess it is time for me to leave a reply to this discussion. I want to clarify which thoughts I had about safety when writing this Instructable.

All of you are totally right, working on tube based devices is dangerous. As is working on any device that is directly operated from 230V. Without any prior knowledge about tube radios it was obvious that there have to be several wires directly attached to the power cord and therefor beeing live with 230V.

Another point I have is that the first thing you find out on google when searching for tube radios is that they are dangerous. Which is why I left the part were I worked on the radios circuits itself as vague as possible so that you always have to do your own research. Only to find out how to distinguish good caps, bad caps, resistors and inductors and where which wire leads took me weeks and you can´t do weeks of research on tube radios without finding out that they are dangerous.

Yes I could have added a warning (and I guess I will) but at least my common sense (and I hope I´m not alone) tells me not to touch blank wires on a plugged in device when I don´t exactly know what I am doing.

[pdavis19]

The problem with tube equipment is that even after you turn it off and unplug it, the electrolytic filter caps can still retain enough charge to kill you. They'll usually drain (as there's usually a path to ground in the circuit, even when it's off). But it can sometimes take minutes to discharge the filter caps and if there's no path to ground, there's no bleeder resistor and if the caps aren't leaky, they can stay charged for WEEKS!! The bottom line is you always assume the electrolytics are charged until you've verified with a meter that they're discharged.

[yrralguthrie]

Both vacuum tube amplifiers and radios do have electrolytic capacitors and the voltage on them can be several hundred volts. However these capacitors are about 33uf or so at the rated voltage and they discharge quickly. Even in old gear those capacitors are quite small, and they don't have a lot of energy to begin with. Both are dangerous to stick your finger in if the gear is plugged in and turned on.

My sarcastic post was meant to insinuate that if you were going to work on tube type radios perhaps you should not need a warning to turn it off and unplug it first.

The electrolytic capacitors referred to in this post incorrectly are found in high current linear (not switching)power supplies rectified by solid state diodes. Some of them can be 2-3 inches across and 5-7 inches tall. And good ones will hold a charge for several days. They are not found in old traditional tube type equipment. It's not the voltage that kills, but the current. Or actually the totality of the two.

[PatrickS291]

Can anyone point me towards a suitable 5V 3A AC/DC Converter? I'm undertaking a similar project with an old Sony Reciever. Thanks

[yrralguthrie]

A tube type superhet radio does not have large electrolytic capacitors. The capacitors in this type of radio discharge quickly and are can be replaced with ceramic or disc ceramic. The B+ power supply does have a small, about 45uf 160-200 volt electrolytic. However the rectifier is a tube and so there is a load resistor, (not bleed). No bleed resister is needed since that capacitor discharges quickly. If you touched it when the radio was plugged in and turned on then you would get a nasty shock. Or if you touch a lot of other bare wires you would also, enough to kill you. That capacitor might hurt if you touched it immediately after the radio was unplugged, but it about as likely to kill you as running into a garage door with your head.
Large electrolytic capacitors are used in high current and/or voltage linear power supplies.
Most tube type consumer equipment was pretty safe when unplugged. Using it while in the tub taking a bath might get a person killed.

[onemoroni1]

Very nice project and modern adaption. Would ypu consider an updated speaker?

[Cliffystones]

If you could find a speaker that would mount in place of the original, it would make little if any difference. Most newer speakers are dependent on the properly designed enclosure to produce the best quality sound. The best thing would be to have the original rebuilt with a new voice coil and cone. I tried the new speaker idea in a jukebox and the sound quality wasn't any better so I had the originals rebuilt,

[Cliffystones]

Yours is a wonderful idea. I am especially happy that you didn't "gut" the radio as there are so few left and they ain't makin' any more!

I also had an idea for a simpler approach. Just install a Bluetooth receiver module in the radio, then stream Spotify, or pretty much any music service from your phone/tablet. Of course this wouldn't be a stand-alone unit like you've created, which I love as well.

[lspicer]

Runeaudio:

Runeaudio is an OS that can be downloaded to your SD card.(

http://www.runeaudio.com/runeaudio-runs-raspberry-pi-3-model-b/ ) It will allow you to log into your Spotity account. It is headless and can be controlled from a smartphone. Also, you can add music stored on USB memory sticks. I love your whole concept and your Instructable is awesome. A little more detail to safety is recommended but awesome none the less.

http://www.runeaudio.com/runeaudio-runs-raspberry-pi-3-model-b/

[ericjamesl]

Amazing

[bruce.desertrat]

Very nice! I particularly like that you retained the original radio functionality!

[ebolisatech]

Nice project!! I was wondering if you still have the radio´s diagrams. I've a similar radio and I'd appreciate if you can send me a copy of them. Thanks.