In fairness, if you have developed an ear that is sharp to identify harsh highs, finding a good tweeter is quite difficult. Again, in this game, cost will not tell you the quality of sound emanating from the driver. I sometimes end up with a number - but when I found something good, I stock some of them for future use just in case, especially if they are dirt cheap.
In my wharf 8.3 with 86db in my previous life, adding a good found (P100/pair piezo with 107db sensitivity does the trick). For the speaker not to see the new device, got to put a series resistor to equalize the 107db to 86db. The cross over is built on the tweeter, and the high value resistor does not impact on the total impedance of the speaker as seen by the amplifier.
Too bad, wen I came back to buy more tweeters of that brand, nowhere can I find any more stocks - even in other stores. many piezo tweets I tried sound harsh / coarse. But once in a while, a gold is among the trashes of pretenders.
Another option I found early on is to buy vintage drivers. I am fond of vintage horn tweeters from branded speaker makers. I have kenwood metal horns (silver rectangle), round coral horns - high sensitivity drivers being sold cheap because the one selling is clueless or do not care at all. I encountered even a magus metal horn 5 x 10 inches that sound so clean that I stocked it!
But somehow I have to agree with others - those efforts and cost in upgrading capacitors to enhance the highs - especially with those souped up capacitors, tend to cost impractically high, considering the benefit one may derive from it, if there is - as a matter of fact - any. I have the impression that the difference in sonic is more a result of altered cross-over frequencies because of capacitor values chosen. I might be wrong since I have not ventured in this path at all.
