where companies must have gone wrong is not copywriting the look , electronic and cosmetic 'packaging' and 'likeness' of the item. That can be protected for 100 years in the US. So when companies steal the 'likeness' of product even though the circuitry is no longer patented (since that is 20 years term) the likeness cannot be used if the packaging was copywritten. So in other words if say Neve was an America company and had they copy-written the vertical 'look' color scheme, Marconi knob style module 'likeness' of the 1073
or however you describe it , all the cloners could be sued for copyright infringement. Well actually only one company stoops that low to steal the actual look too.
Many companies only patten
the design and that expires as we all know. But often they do not copyright the 'identity' That's where the problem is. Many companies I've worked for do both. But it is very expensive and takes time so often they don't bother. Since technology life is so short , Especially electronics design. 20 years for an electronics design is archaic by some standards. But as we know as gear heads, older designs and components they used have the mojo.
See companies like Fender Gibson etc... must have been smart , if you build and sell guitars with a Strat headstock shape or if you build an Les Paul
guitar with body and Les Paul
style head stock you can be sued based on 'likeness' Apparently these audio gear companies didn't bother to cover that aspect. They probably only copyrighted or trademarked the logo. In some case not even the name. Since say '312' or '1073' are stolen all the time. They forgot to copyright that stuff or didn't bother. It's a shame, too many people profiting off someone elses creativity.