Must be the cone speakers that contribute to such high level of voice fidelity. If I'm not mistaken, this is the first use of cone speakers in a large-scale warning siren.

What a unique machine, I always liked how Sentry pressed those three ring grooves into the sheet metal of the horn. Interesting to see how much space is left over in that rotator housing.

The neck and intake cone were not perfectly segregated from each other - the chopper just loosely took up space inside the housing - so I suppose blocking the neck would simply direct a portion of the sound that is reverberating inside the chamber to try and belch out the front bell. I'm sure B&...

Weren't the early MDs available with an optional motor-brake? And as for true pulsed, I'm not sure how one could elegantly fit any damper mechanism over the intake bell.

Can't say I've ever come across a siren or photo of one that I found truly displeasing to look at, but as far as bland goes the 2001-130 always looked like someone had salvaged a tin bucket and an old refrigerator, bolted them together and slapped white paint on.

If memory serves me right, Ben had a collection of pics from a few restoration jobs of his on his long-defunct web page. Shame that CTI's own website was never more than a crummy brochure page.

Darn, I never thought the day would come where a collector would get his hands on one of these bad boys. I thought they all bit the dust. Congrats! I'm impressed with those output figures considering the rather modest power demand; like everyone else at the time I was always under the impression tha...

Hey, sorry for getting back to you so late. Not sure whether all three went off. I suppose the other two roared to life as well, but standing a stone's throw away from that one, it completely drowned out everything else. The hi-lo timing is a little odd, that's for sure. Shame they test so short.

Went out and recorded one of Suncor Energy's three Thunderbolt 1003s. Only time I've heard the 'Bolt before was from the train station about three miles away maybe ten years ago, so I thought I'd sneak a view from the park right behind the cemetery, 100 feet from the siren! It's perched maybe fiftee...

I really like that narrow 415/425 Hz interval.