I used a different kind of elastic restoring force, one derived from an air spring, instead of the mechanical springs of the suspensions.
This turned out to be not too difficult - after all, the speaker has a cabinet which encloses a cushion of elastic air.
The AR-3a was Acoustic Research´s High-end speaker and customers had to pay around 500$ to buy a pair, a fortune at the time.
In the manual (see below), the company describes the AR-3a as “the best home speaker system we know how to make” and it is even today an impressing vintage speaker.
When the AR-3a was introduced in the mid 60ies it took over the role of the AR-3.
In it, eight current reviewers of TAS, including founder Harry Pearson, were asked to name the dozen speakers which they thought to be the 12 most significant loudspeakers of all time.
By 1966 Acoustic Research held more than a third of the US market shares in the speaker market, the highest share ever measured in the industry.
An old AR-3a is definitely worth it to be refoamed.
Most listeners couldn’t tell the difference between the speakers and the musicians, a testament to the AR-3’s quality.
Eventually, the AR-3 was replaced by the AR-3a, a modified version that used the same woofer but offered improved dome midrange and tweeter drivers that created even wider dispersion.