Update on that: Usually that type of horn you would see on the VA4-series signals, like this:
Audibly, it sounds identical to the (later-generation) U-MMT horn/strobe or Wheelock EH horn in Continuous. SAE also made a speaker version, but most I’ve seen use horns.
I know this one is a Gentex Commander like those I’ve seen in Ben Schumin’ collection and at Shaw’s in Stoughton, MA, but I’ve never seen one quite like this. Name that Gentex fire alarm.
That’s easy; a Space Age Electronics 2DCD horn behind an AV32 light plate! That was a very common SAE configuration in the 1970s and 1980s, especially in FCI systems.
There WAS a mechanical horn version of that one, it had a different horn than a 9838. I think it was the horn that the 9219 and U-HN, NH and HNH series had.
They were not ALWAYS MTL horn/strobes! There were 3-tone versions and there were speaker versions.
schumin’s collection is not THE BEST COLLECTION… and he does not have the ONLY TYPES… His MTL Is only an example of a SERIES.
When I said MTL, I was just referring to the series, not any specific model. If it is a horn/strobe, it’s most likely an 8-tone version, as those were the most common models. There were single-tone, 3-tone, and chime models, but I have yet to come across any of them.
MTL isnt the correct name for the entire series though. Just saying.
Fun Fact: The strobe is known as W-Series or S15. The Faraday model number for the 15 candella W-Series strobe is 5527-W . This is on the back of the strobe portion of my HES-STW.