The AR15 was made in the late 70s by Acoustic Research and used what was known as an acoustic suspension design.
This basically means that the speaker doesn’t have a tuned bass port so the enclosure is airtight. Obviously the paper cone of a speaker isn’t going to form an airtight seal but I think that’s how the marketing went back then!
They needed to be placed near a wall to sound best, hence they were sold as bookshelf speakers. Unlike a lot of modern small speakers they were fitted with 8″ mid / woofers.
The problem with this speaker was one of the binding posts had rusted solid so you couldn’t undo it to clamp the speaker cable to it. It was also very difficult to remove!
Once I’d got them removed I fitted new banana posts. These allow you to use speaker cables with banana plugs on them or just bare wires.
If you’re looking to buy old AR speakers the foam around the edge of the woofer falls apart over the years so check before you buy. I saw some at a local auction house and took the front grill off for a look and the woofers hardly had any of the foam surround left!
The woofers can be refoamed or alternative new woofers fitted. I’d probably opt for new woofers as the original paper cones might have deteriorated and gone soft over the years.
Little bits of black foam inside these speaker cabinets suggested that the woofers in these old AR15s had been replaced.
The printing on the back of the woofer just said Made in Taiwan with a part number of 55-1195 which looked decidedly non Acoustic Research.
Looking that number up shows a woofer from Farnell Components that has a polypropylene cone and is priced at £15 so the bass drivers in these enclosures aren’t original. That sort of changes the value of them somewhat, especially if you’re considering buying some.
So, what do these old modified Acoustic Research AR15 speakers sound like?
Very good considering they don’t appear to have the original bass drivers in them!
Modern speaker units will be designed using all sorts of modern CAD software and materials so these modern replacements could be as good as the 70s designed originals.
I bought some of the smaller AR18s back when they were new and they were excellent. Back then they cost about £80. The foam around the edge of the woofer eventually fell apart in those as well. Like the AR18, these AR15s use an 8″ woofer but in a bigger cabinet.
This cheap driver should also fit the smaller AR18 cabinet as I believe it uses the same woofer.
There will be better replacement drivers but they’d cost a lot more. Half the battle with replacement drivers is finding something that fits the cutout and has the mounting bolt holes in the same place. The mounting holes in the baffle usually have threaded metal inserts.
You don’t want to start drilling holes in the front baffle as you will fill the cabinet with sawdust!
The bottom left image shows part of the crossover network fitted to the inside back panel. All the glue was put there by Acoustic Research, presumably to stop it rattling with the bass as they haven’t used a PCB.
The switch reduces the signal level to the tweeter.
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