Wayne Parham Messages: 18757 Registered: January 2001
Illuminati (33rd Degree)
You're right that these compression drivers will go for many years without issue. You'll never replace a diaphragm when driving your speakers with just 75 watts. After the crossover, that's about 7 watts across the driver terminals.
Compression drivers are very robust, much more than any other kind of tweeter. Because of that and their unusually high efficiency, they are used in prosound. In that application, they're pushed hard and sometimes experience failures. Compression drivers in the used market are generally retired prosound drivers, often with damaged diaphragms. So that's why you see replacement diaphragms. They're user-replaceable.