Question Seeking help to get a pair of old speakers working

Apr 22, 2020
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Hello friends,
I recently stumbled upon a pair of old Sound Dynamics speakers left on the road by someone in my neighbourhood. There was a sign on them encouraging someone to make use of them, as they apparently work perfectly fine. In my boredom-fuelled optimism and probably more than a little overconfidence in my own capabilities, I decided to take them home and try to get them working as a little pet project during quarantine. The only problem is that I have exactly zero knowledge of audio systems, or electronics in general for that matter. This was actually part of the motivation for taking on a project like this, was to possibly learn a new skill and come out of quarantine as a new, improved, and enriched man ready to take on the world.
However the more I google, the less I know where to begin. Clearly it's a bit more complicated than plugging in the black and red cords to the black and red holes, especially given that they are pretty old speakers. I can hear the techies and AV people just scoffing at my ignorant ambition. But regardless, I'm ready to learn and feel dumb if someone is willing to give guidance and be patient with me.

So here are the facts: (assuming that these speakers are in good working condition as the sign said)
-The speakers are Sound Dynamics 1200 SMT
-There are no cords on the outside of the speakers to connect to a power source or receiver, nor are there ports to plug in such cords. But there are red and black clip type things
-The clips on the back of one of the speakers have been broken off

Here are some pictures:
https://drive.google.com/file/d/1Bj5nBtqMHMWWdY57b6DPRx-F7l-Vqm95/view?usp=sharing
https://drive.google.com/file/d/1Bi-oJ_I_MB9gfxebWQpyHtDsY9jVw5bY/view?usp=sharing


What do you guys think? Is it possible to get these up and running, or are they beyond saving? Can something like this be explained as if I was a ten year old boy, or would it be too complicated for me to read and follow instructions? Is it even worth trying to get these working, even if it's just for fun, or should I just put them out by the road as well? I am willing to invest a little bit into these if you think it is worth it, as I'm aware that I'll be needing some more components.

If you can answer any of the above questions, please feel free. I'm willing to accept any sort of advice or direction.

Thanks!
 

Sonic Illusions

Prominent
Feb 16, 2019
173
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This sounds like a GREAT project. I've taken on many restorations, but mostly build new from scratch.

Can you take some shots with the grills off? I'd like to see the woofers' suspensions (surrounds). Typically, they don't last. If they were played with rotted surrounds, the misalignment of the coil in the magnet gap can destroy the coil. Hopefully, yours are in good shape, but that would be very unusual for foam surrounds to last that long. If they're rotted, then you'll need to replace them. This is a tricky job, but if you do the research, Google some Youtube surround restorations, you can do it. If you do, be careful with putting too much adhesive on or using it unevenly, as you don't want to change the moving mass (weight) of the cone. That can change the response of the woofer/ passive radiator.

There are many companies who also offer this service.

View: https://youtu.be/jwcfP5pKeek


As for the terminal plates, check these out. If the dimensions work, great. If not, fab a plate from hard plastic and drill for banana binding posts. MUCH better than those crappy spring clips. You can use bare wire or banana plugs. Remember to use a good sealant for an AIR TIGHT seal.

https://www.parts-express.com/parts-express-gold-binding-post-banana-jack-5-way-speaker-terminal--260-302

Those old L-pads (Tweeter level attenuators) can get corroded over time. Use a good quality electronic contact cleaner and lubricant.
 
Last edited:
Apr 22, 2020
2
0
10
0
This sounds like a GREAT project. I've taken on many restorations, but mostly build new from scratch.

Can you take some shots with the grills off? I'd like to see the woofers' suspensions (surrounds). Typically, they don't last. If they were played with rotted surrounds, the misalignment of the coil in the magnet gap can destroy the coil. Hopefully, yours are in good shape, but that would be very unusual for foam surrounds to last that long. If they're rotted, then you'll need to replace them. This is a tricky job, but if you do the research, Google some Youtube surround restorations, you can do it. If you do, be careful with putting too much adhesive on or using it unevenly, as you don't want to change the moving mass (weight) of the cone. That can change the response of the woofer/ passive radiator.

There are many companies who also offer this service.

View: https://youtu.be/jwcfP5pKeek


As for the terminal plates, check these out. If the dimensions work, great. If not, fab a plate from hard plastic and drill for banana binding posts. MUCH better than those crappy spring clips. You can use bare wire or banana plugs. Remember to use a good sealant for an AIR TIGHT seal.

https://www.parts-express.com/parts-express-gold-binding-post-banana-jack-5-way-speaker-terminal--260-302

Those old L-pads (Tweeter level attenuators) can get corroded over time. Use a good quality electronic contact cleaner and lubricant.
Hey there! Thanks for the encouragement, and for taking the time to respond. I agree, I thought it might be fun to try it out!

Here are some pictures of under the grills:
https://drive.google.com/file/d/1C7cCFm0DkgT-fy4IzTdpsVS6fqOvRapC/view?usp=sharing

It looks like they have deteriorated a fair bit. Should I focus on replacing these first as a first priority, or the terminals?
 

Sonic Illusions

Prominent
Feb 16, 2019
173
19
665
5
Well it really doesn't matter which you do first because they can't be used. Test the woofers with a 1.5V battery if you don't have a multitester (for ohms). You'll hear a pop if they work. You'll need to take some measurements and call the guys at Parts Express, so they can get you what you need. Also ask about the contact adhesive for re-bonding the PRs. Anything not glued down will make noise. Measure your terminal plates as well. They may stock items that fit W/O modifications to your spkrs or the terminal plates. By ordering everything you need, you'll save on shipping costs.
 
Last edited:

hang-the-9

Titan
Moderator
-There are no cords on the outside of the speakers to connect to a power source or receiver, nor are there ports to plug in such cords. But there are red and black clip type things
-The clips on the back of one of the speakers have been broken off

Here are some pictures:
https://drive.google.com/file/d/1Bj5nBtqMHMWWdY57b6DPRx-F7l-Vqm95/view?usp=sharing
https://drive.google.com/file/d/1Bi-oJ_I_MB9gfxebWQpyHtDsY9jVw5bY/view?usp=sharing


What do you guys think? Is it possible to get these up and running, or are they beyond saving? Can something like this be explained as if I was a ten year old boy, or would it be too complicated for me to read and follow instructions? Is it even worth trying to get these working, even if it's just for fun, or should I just put them out by the road as well? I am willing to invest a little bit into these if you think it is worth it, as I'm aware that I'll be needing some more components.

If you can answer any of the above questions, please feel free. I'm willing to accept any sort of advice or direction.

Thanks!
Those red and black clip type things ARE the connections to the amp/receiver, those are pretty standard speaker connections, one of several out there. From the looks of them you will need to replace them.

Also will need to re-foam the speakers from the other picture. Should not be too hard, really all you need to do is pay attention how things are connected and wire them in the same way. I suggest several pictures before you start and work on one thing at a time.

I have replaced the surround foams on several speakers, it's not too hard.
 

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