We have developed a habit each Friday to go to our local Tip shop. They often have a few old speakers stacked in a corner. I don’t need any more but I always have a look, just in case there is something special that wants to come home with me.
Normally there are a couple of things I look for. Firstly if there is just a hole with a cable hanging out, it loses marks. I’m looking for ones with proper terminals. Second, I look at the cabinet. If it is very light for its size, I presume it has either lightweight drivers and/or thin timber construction and walk away.
One day a single speaker cabinet caught my eye. What I noticed was that it had a badge with AR-7. I don’t know a lot about vintage speakers, but I do know a little about AR or Acoustic Research as it was also known. I know this as I purchased a pair of AR-16 speakers about 30 years ago and I use them every day with our TV. I grabbed the speaker and paid a few dollars and headed out.
AR-7’s were produced around the early 70’s. They were sold as bookshelf speakers. I didn’t have high hopes. It was only one of a pair. There was a big dent in the bottom, presumably when it likely landed in one of the big tip bins. Also, the rubber surround on the AR-16’s I purchased had long crumbled, and they were only about 20 years old at the time. This one is over 50 years old. I expected this would need replacing.
Before
It’s not immediately obvious in the picture, but the foam surround for the woofer has completely gone. I’ve replaced the surround on a few speakers and it’s not expensive to do, even a badger like myself can do it. The tweeter has been pushed in so it will also need some work.
This is the back of the woofer. It’s got a fairly big magnet. It’s the same model woofer that is in the AR-16s.
I read that AR-7s cost US$70 in 1973. I’m not sure if that is for one or a pair. In today’s dollars that is about $500. That’s a significant amount. I thought they could have been a bit neater attaching the Velcro for the grill.
That is a nasty dent.
This is the ‘crossover’ sealed and held in with a lot of glue. I did not expect this. I think what we have here is a pair of wires going directly from the screw terminals to the woofer. The tweeter is connected via a single capacitor with a resistor for flat/normal that can be switched in or bypassed. If I am correct, that is very basic crossover.
The back of the cabinet. Notice the Flat and Normal switch. The connections marked 1 and 2, instead of + and -.
An info sheet is attached to the back. I guess I will be setting up a monaural system.
After
I didn’t have much success with the tweeter. I tried to encourage the dome back into shape, but it had degraded. I firmed it up with some PVA glue, but it sure looks ugly. It will have to do.
I redid the foam for the woofer with this foam and this glue from AliExpress. There seem to be at least two types of replacement foam. The one I chose is a rubber surround. The other type is more like foam. I don’t know which is best, but this at least feels like good quality and I would use it again.
I don’t know the correct procedure for redoing the surround. I’m sure there is lots of info out there. The way I did it was to carefully scrape off all the old foam and glue. Then I glued the new surround to the speaker cone taking care to make sure it is centred. When that is dry I ran glue around the metal frame and glued the surround down with lots of clamps, clips or pegs. while it is still wet, I gently pushed the centre down to make sure it the voice coil was not scraping on the magnet.
It has probably changed the sound of the speaker and I wouldn’t do this on anything of real value, but it’s enjoyable to get an old speaker working again.
The dent has been sort of fixed. I massaged some glue into the chipboard and veneer and then clamped it firm. It’s obvious it is still there but now it’s a part of the story instead of a defect. Or at least that’s how Im looking at it. I also put a clear coat of polyurethane over all the veneer.
I made a frame up for a grill. This turned out to be the hardest part. It was made worse because I used some grill clips salvaged from another pair of speakers which were not a very suitable choice. It would have been much easier to buy some new grill clips.
Back of the new grill. Before assembling it I cut a groove to push the cloth and glue into. I cut a spare groove in one end because I wasn’t paying attention.
I painted the front and back black. I don’t like the original spotty look.
Finally with the grill cloth. It’s a different style of grill, but I prefer it.
Here it is in use. I have the switch on the back set to flat and have it connected to my SW radio. It sounds very good for this use as it cuts out a lot of high frequency hiss.
It’s not perfect, and it was never going to be. But it works, it sounds good, and it’s back doing what it was made for.
It is satisfying to have saved it and brought it back to life.
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