The Siren Board

Surprised this hasn't been discussed here. I am referring to the air raid sirens that Toronto and Chicago had from the 1950's to the '80's. I saw a picture of several of them being taken down in Toronto and the name of the manufacturer said "CLM Industries".

In the movie "The Blues Brothers" they featured this siren being taken down from a poll in Chicago and used as Jake and Elwood's mobile PA system. It's a big sucker and I've never heard what it sounded like.

Do any of these still exist in Chicago? Anyone know what I'm talking about?? LOL.

These are discussed here every now and then, We are aware of the "Blues Brothers" siren, There are none left in Chicago that we know of. Although I Toronto, And Ontario still has some that they sound I believe. There Pretty much a Canadian allertor.

I still have not found any evidence that Chicago ever had these. From what I have understood, they had around 5 Chryslers, a mixture of around 50 or so STL-10's and Model 5's. And around 20 or 30 tbolts. When the system was shut down in 1995, there were 88 sirens. There were tbolts, model 5's and STL-10's. The Chryslers were gone long before then. Ive tried to find final records on the old system, but the city no longer has them. Every once in awhile I still see some old sirens still up on fire houses, factories, and schools, but very, very few.

Currently in the process of restoring one from my hometown to be displayed at our museum this spring.[img]

MisterRe wrote: ↑

Sun Apr 14, 2019 6:27 pm

Currently in the process of restoring one from my hometown to be displayed at our museum this spring.[img]

I wonder how they could’ve possibly been 10/12 Port when there appears to be a rotor/stator in the rear of the siren and that rotor looks not only unusually small but there’s no way that is either 10 or 12 Port...I have no idea what that even is. It seems that it would’ve made more sense to put the dual toned rotor/stator in the front since that front cone is where the air intake is, but from your picture it appears sound was projected from not only the top horn but from the bottom as well Judi g by the front of other CLM’s I’ve seen in pictures (the intake is in the front come as well as a small opening on the front cone that projects sound through sort of like the ACA Penetrator series design).

If that part on the back really did project sound through the top horn as well as on the front, how would that rear rotor/stator get air in to produce the sound, because I can’t see any kind of air intake on that side. Interesting...

The pitch is not reliant on the port count on the stator. The pitch is based on how many ports are in the chopper. That's why the Thunderbolt sounds 5/6 port with only one stator port.

The only reason why the ports on the stator equal the ports on the rotor is because the sound is then linear, and, I believe, the siren itself will be more efficient. Don't quote me on that last point though! I really don't know wht CLM decided to use such a short horn and therefore only have space for 3 ports, but they did, and it sure is interesting.

fire_freak_57 wrote: ↑

Sun Apr 14, 2019 7:24 pm

If that part on the back really did project sound through the top horn as well as on the front, how would that rear rotor/stator get air in to produce the sound, because I can’t see any kind of air intake on that side. Interesting...

The slightly rectangular tail on the rear of the siren is open at the bottom. It acts as an intake for the rear chopper assembly.

Remingtoncountry wrote: ↑

Thu Apr 25, 2019 4:13 am

fire_freak_57 wrote: ↑

Sun Apr 14, 2019 7:24 pm

If that part on the back really did project sound through the top horn as well as on the front, how would that rear rotor/stator get air in to produce the sound, because I can’t see any kind of air intake on that side. Interesting...

The slightly rectangular tail on the rear of the siren is open at the bottom. It acts as an intake for the rear chopper assembly.

And the smaller horn actually project sound.

IIRC I've read an article saying that Canada required a Dual Tone siren as a part of their CD System and the CLM Model 92729DP, Type-L (The actual model of this particular CLM siren, I think better reffered as Type-L (And I assume other models i.e the Mailbox and the bigger omnidirectional (The one that uses skirts with the screen at the circumference of the skirts) maybe Type-S and Type-M, respecively)) maybe should be single-tone but to qualify for CD usage it must project at least a bit audible second tone.

Though IMO that's redundant.