Here we have one 555 diaphragm that has now been replaced from 13Audio inventory. The western electric 555 is now back to factory specifications and the owner can enjoy.
This driver was purchased by the owner online at eBay. All the readings were correct and the voice coil was 12,7ohms, just about where it should be. Yet this was what the diaphragm was actually like, useless. I see this often. Some have minor corrosion or damage yet still play albeit far from ideal. I always wonder how many users of original 555 drivers actually know what the true condition is and if they are delivering sound as they should? Hummm….
One can ask the seller to open the 555 driver to see the condition of the diaphragm beyond the DCR reading. However beware that an inexperienced person will invariably damage the voice coil during that process rendering the driver useless.
I have sufficient stock of original western electric 555 drivers all serviced for the big horns I make along with some replacement diaphragms. In all the years I’ve been installing western electric systems around the world I have never experienced any serviced ones breaking. Note that we are using these drivers in homes and even at high sound levels we are nothing close to what they were designed to endure. They were designed to fill large, very very large, cinemas theaters with a lot of sound! Playing them at home is holidays for them. Yet they are no youngsters and what we see below is the work of the natural elements over 90 years. TLC is all that is needed.
I’m not sure how a diaphragm can get into this condition, maybe salt from an Oceanside location?
Who knows? 90 years about and probably not used for many of those years.