No easy answer to this question. Some speakers used material for the surround that deteriorated after a fairly short time and would turn to dust. This was primarily a problem with speakers made in the 1980s (I hope no one is still using that kind of material).
I have a set of horn compression drivers that were made around 1939 that work perfectly and are still very highly sought after.
I have a set of horn compression drivers that were made around 1939 that work perfectly and are still very highly sought after.