Please define "improved".
In terms of sound quality, I do not think much has changed. 30 year old polystyrene caps were excellent, they still are.
If however, you are referring to their reliability, closer tolerances and higher temperature ratings, then yes, the more modern ones have greatly improved relative to their counterparts.
In terms of sound quality, I do not think much has changed. 30 year old polystyrene caps were excellent, they still are.
If however, you are referring to their reliability, closer tolerances and higher temperature ratings, then yes, the more modern ones have greatly improved relative to their counterparts.