I bought B&W Matrix 803 used six months ago These are the original model with one 7" woofer, date of manufacture 1990. I had to replace a burnt tweeter, so I did both successfully, and I love these with the ST-120 in a very cozy room. I think I hear slight variation in response, however.
I know from research that the crossover design is pretty simple, but that B&W perhaps used inferior components i.e. cheap electrolytics. I have all the values for the parts - two or three chokes and two or three caps. I am considering upgrading these components. Seems like a fairly easy project. Any suggestions???? And is it in fact the case that these crossover elements can degrade over 25 years???