Restoring a 1950s Schoolroom Speaker

My effort to bring a piece of history into the 21st century

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I got an old Rauland intercom speaker from my elementary school before it was demolished. The veneer was a bit beat up, but the speaker still worked. I first got it working with some headphone wires, but the sound isn't very good and my wiring is shoddy. Now, I want to replace the speaker/amplifier, add Bluetooth receiving, and fix up the facade.

This project will probably be on hold until winter or summer break. I don't have most of the tools and parts I will need for it.

This project has 3 parts:

1. Replace the speaker and/or amplifier. I have several car speakers that might work for this and have better sound, but the main issue is volume. The current amplifier isn't very powerful, so I'd like to change that. I might be able to add multiple speakers, too.

2. Add smarts. I don't like having a wire running to the speaker from my computer for two reasons. First, it doesn't look good because it originally was wired through the school's walls. Second, the headphones cord I have right now is too short, so I had to extend it with some extra wire and scotch tape (for lack of better materials in my dorm). Instead, I want to add either Bluetooth or AirPlay receiving. I'll probably end up using either an Arduino with a Bluetooth module or a Raspberry Pi with a WiFi adapter for this. Going wireless will also require a battery pack and some way to conserve power.

3. Fix the veneer. It's currently pretty beat up and has paint marks over the sides and even the front. I want to fix it up while preserving the original look, but this will probably involve replacing the entire veneer. Alternatively, I could simply paint it, since the wood grain pattern is very subtle anyway. I would still need to patch up some minor damage to the wood.

Originally, the speakers were used as two-way communication between the office and the classrooms. This works because speakers can also act as (low-quality) microphones when used in reverse. It would be really cool to get that working as well, but that's not part of the core of the project.

  • Ditching Wires (I'm FREE!)

    Alex Cordonnier01/14/2015 at 00:58 0 comments

    Once my new Bluetooth module came in (same model as before but different seller), I was ready to make the speaker wireless. First, I verified that the Bluetooth module did indeed work. Next, I cut up the line-in cable and soldered it to my amplifier board. Unfortunately, the wires were very thin and hard to work with.

    Then I took the case and the USB shield off the Bluetooth module like [Tony] did, and I soldered power and ground leads onto the USB connector for the amplifier board.

    I cut up a very short USB cable that I got from BoilerMake this fall so I could use it to power both boards. I soldered power and ground from the USB cable to the USB connector on the Bluetooth module. That way, I could use a USB battery pack to power it.

    I soldered the final leads onto the amplifier board, hooked it up to the speaker, and...


    I tested each component before soldering everything, and it all worked. After lots of frustration, I determined that the amplifier board died. I must have let the soldering iron on it for too long. At least the audio works, if quietly, as long as I bypass the amplifier.

    I'm probably going to end up buying another amplifier board and have a go at it again. But for now, at least, it works.

  • Fixing the veneer, painting, and more

    Alex Cordonnier01/09/2015 at 03:00 0 comments

    Well, first off, the Bluetooth module I bought was DOA. I returned it and am probably going to buy a similar model from a different seller on Amazon soon.

    In the meantime, I did a lot of work on the exterior, and it's looking nice. I first lightly sanded off the dripped paint from the front, bottom, and top. The top had far more paint drips than the rest, so rather than sand off the entire veneer, I mostly let it go. It's going to be too high to see when wall mounted, anyway.

    Once I finished sanding, there were obvious marks left on the veneer. The first thing I tried to do was fill them in with wood filler "crayons," which was mildly successful but still not great. Then I tried brown shoe polish, and voilà! It looked beautiful.

    Next, there were two holes in the veneer, both on the front. One was extremely prominent. I used some wood putty to fill them, and while they look better, the big one is still somewhat noticeable. I was pleasantly surprised that the color matched pretty well because it's not paintable wood putty.

    I took the speaker out, and it seems to have held up surprisingly well over the years. No signs of any damage, although it was quite dusty. I was originally going to replace the speaker cloth, but when I took it out, I realized it too was in much better condition than I thought. I washed out the dust and grime, then flipped it inside out so the less faded side was facing out. My sister kindly painted the Rauland logo on the new front. While I was at it, I glued the broken cross bars back together.

    The last thing to do was fix the sides. They were simply painted, but they had large paint drips. I sanded these off, but that left marks on the rest of the paint. I ended up painting over the sides with as close to the same shade of brown as I could mix. Unfortunately, it dried much lighter than I had anticipated, so it's a cool brown instead of warm brown like the original.

    The exterior should now be finished. The amplifier chip I bought works great, so all that's left is Bluetooth.

  • Bluetooth and Audio Amp

    Alex Cordonnier12/04/2014 at 05:11 0 comments

    Since my last update, I've learned a lot more about Bluetooth (for another project) and decided to give it a try for this project instead of AirPlay. I saw this project on Hackaday and bought the same adapter from Amazon on sale for $7.50. I also bought an audio amplifier for $6.78, also from Amazon.

    I'm planning to remove the enclosure from the Bluetooth receiver so I can solder directly to it. I'll hook up the +5V and ground from the Bluetooth receiver to the audio amp, as well as the left and right audio channels. Then it's a simple matter of hooking the speaker up to the right audio channel (since I only have a single speaker) and plugging it all into the USB battery pack.

    Also, the audio amplifier has a built-in potentiometer that controls the volume, so I might mount it onto the speaker enclosure.

  • AirPlay

    Alex Cordonnier10/26/2014 at 19:27 0 comments

    I had a great idea today. Why not use my old iPod touch as an AirPlay receiver, rather than a Raspberry Pi?

    I installed Airfoil, but it crashed immediately on opening the app. Then I installed AirPlayServer, which seemed to work. However, the AirPlay connection from iTunes was pretty shaky and tended to crash iTunes a few times before it started working. Once it did, I hooked it up to my speaker, and the music was almost inaudible. If this is going to work, I'm going to need to boost the volume a lot.

    On the plus side, I acquired a portable battery pack from BoilerMake last weekend. It's 5V 1A 2200mAh, so it should be enough to power an iPod or a Raspberry Pi Model A for a few hours. We'll see how things turn out.

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DainBramage wrote 01/14/2015 at 04:58 point

If you can, use the original speaker. Many old PA speakers actually have a rich, full sound when driven properly. I have been using 6" PA speakers rescued from a church dumpster in my home theater system, and they sound fantastic.

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Alex Cordonnier wrote 01/14/2015 at 23:31 point

Interesting. I didn't realize that PA systems use good speakers. In any case, I'm not going to replace the speaker in this project because it's in better condition than I originally thought and because my stash of extra speakers mysteriously disappeared.

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