The distortion is typical of a 4-5” woofer in a sealed box of that era. And non linear distortion and compression are really just 2 sides of the same coin.
Anyway, this is what my fellow Australian
@restorer-john has been saying all along. The hey day of audio was in the late the 20th century.
Ken Rockwell said it a decade ago:
All the clever engineers were done with audio by the 80s. Home theatre and Video was the next big thing. Simultaneously at the same time computers took off and captured the imagination of youngsters everywhere. And then software!
When I was in Engineering school in the 2000s all us younguns wanted to be be the next Bill Gates or work for Microsoft.
Not join Sony and build the next best speaker…
This speaker (apart from limited bass) measures well; has a waveguide; aluminium enclosures. All designed and made before I was born.