Just a quick blurb on these little guys as I have not found much on them within the forum.
Now I cannot say for certain, but my best guess is (correct me if im wrong here) these were installed on B1A style ringers to help make a set more identifiable when it rang, especially if there were multiple extensions in proximity. Now you could pair up the bells to get two different tones between two sets (hi/hi) (lo/lo) but the dampener does quite a bit more. When installed it take the vibration out of the bells, making the ringer sound flat, more like a mechanical buzzer.
Some info here, but doesn't answer your questions.
http://www.classicrotaryphones.com/forum/index.php?topic=17329.0
Per BSP, the 100B gong attachment could be used for both purposes: "Reduced Loudness of Signal", or as "Distinctive Signals for Adjacent Ringers".
Historically different sounds were achieved with the different types of gongs, and gong materials. The 100-type gong attachment already existed for the numbered ringers; this was the 100A type. For B-series ringers it was the 100B. For B ringers different materials were also available.
The other gong attachment for enhancing the sound was the 101A gong attachment which added a resonance cavity within the gong and a closure.
Check out BSP Section C31.205 for number ringers and C31.208 for the B ringers.
Thanks unbeldi and TelePlay
Our WE 466 has one of those on its ringer. You can hear it ring around the 4:15 mark in this video:
https://www.youtube.com/watch?v=4kPVZttaqUM
---Eric
Quote from: ESalter on January 09, 2017, 01:21:21 PM
Our WE 466 has one of those on its ringer. You can hear it ring around the 4:15 mark in this video:
https://www.youtube.com/watch?v=4kPVZttaqUM
---Eric
I do believe I have observed them far more frequently on business telsets than other telephones. I suppose the bells are way too loud for a business environment, sitting 2 or 3 feet away on someone's desk.
As found (not installed properly) when opening a 460 key set:
The 755 only rang the phone on an incoming intercom/local call. Trunk calls were signaled by bells and/or lights at various common locations, and the trunk button lamps in the phone(if it had them). So, having the damper in the phones would make an obvious audible difference between local and trunk calls, besides the fact that the sound would be coming from different locations.
---Eric
Quote from: unbeldi on January 09, 2017, 02:34:34 PM
I do believe I have observed them far more frequently on business telsets than other telephones. I suppose the bells are way too loud for a business environment, sitting 2 or 3 feet away on someone's desk.
As found (not installed properly) when opening a 460 key set:
When were ring indicator lights introduced? The 500s? Looking at modern business phones, most do have some kind of LED to draw the eye. I do not recall reading or seeing ringer modification to ringers in 500s, but as always i could be wrong.