I have seen two different versions of the Twinsonic Lightbar where the center speaker cover was removed and replaced with what appears to be one or two CP100 speakers. The two pictures were from 1970’s movies Speedtrap and The Gauntlet. I was just curious if this was something Federal Signal offered as an option or if it was a retrofit done by a department after purchasing a stock Twinsonic?
Was This Ever A Twinsonic Factory Option?
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I know that Las Vegas Metro used the SD bar with the speaker cover removed, back in the late 70s early 80s.
Definately not a factory Federal option.. problem would be the dome does not seal on the inner side like the SD dome does. If anything department modification.
Bonus like points for a post featuring Red/Amber bars.
Definately not a factory Federal option.. problem would be the dome does not seal on the inner side like the SD dome does. If anything department modification.
Bonus like points for a post featuring Red/Amber bars.
Red/Amber was a thing in AZ, but don’t know if it is still used. I recall seeing R/A Mod11 Twin Beacon Rays back in the day b/c red domes absorbe 85% of candlepower, amber 15%.
As @Stampeed Valkyrie said, Code 3 bars offered the speaker housing delete but had fasteners to secure the inbound side of the domes. Dietz/Yankee/NAPA 911 bars also offered the option as well. In my old stomping grounds of Louisville, KY, a Q was festooned in position:
Louisville FD battalion chief car (district 2)
Jefferson Co. PD (absorbed into Metro Lou PD)
Yankee catalogue
As @Stampeed Valkyrie said, Code 3 bars offered the speaker housing delete but had fasteners to secure the inbound side of the domes. Dietz/Yankee/NAPA 911 bars also offered the option as well. In my old stomping grounds of Louisville, KY, a Q was festooned in position:
Louisville FD battalion chief car (district 2)
Jefferson Co. PD (absorbed into Metro Lou PD)
Yankee catalogue
Check out "Used Cars" for some Red / Amber Twins ... says filmed in Mesa, AZ
South Dakota had Red and Amber c. 1978. Lightbars were Red on Driver side, Amber on Passenger side.
I specifically remember seeing those popular Pontiac police cars with the Red/Amber AeroDynics somewhere in reach of Wall Drug, or maybe the Corn Palace.
Their highway maintenance vehicles had split dome beacons; Amber to the front, and Red to the rear.
I have seen this configuration on a movie based during that era in South Dakota featuring a collector car from the area ... movies wouldn't care about that sort of thing
South Dakota had Red and Amber c. 1978. Lightbars were Red on Driver side, Amber on Passenger side.
I specifically remember seeing those popular Pontiac police cars with the Red/Amber AeroDynics somewhere in reach of Wall Drug, or maybe the Corn Palace.
Their highway maintenance vehicles had split dome beacons; Amber to the front, and Red to the rear.
I have seen this configuration on a movie based during that era in South Dakota featuring a collector car from the area ... movies wouldn't care about that sort of thing
PSE Code 3's SD domes were designed for use on both mini-bar and full size bars, so both ends of the dome were identical. Federal's Twinsonic was not designed as such, so the Federal domes have one end that is sloped and has a retention lip and the other end is flat, the retention being the speaker housing covering the edge of the dome. To put a mechanical siren or large speaker into a Twinsonic, straps would have to be used on the inboard edges of the domes.
Good point. In addition to straps wouldn't you need to seal it too? An SD each side has a motor, a twinsonic the chain runs under the speaker and is exposed through the slats in the speaker base if you remove the grill.
The speaker tray does cover the chain, but there are also drain slots that run along the rear edge of the tray. I have no idea if they were covered or not, but I would presume they were in order to minimize dust intrusion.
The center of the early SD bars (witch were offered with open center) is also not really completely sealed, so that moisture and dirt could get under the rotators
The design of the TwinSonic did a pretty good job of minimizing dirt and moisture intrusion. There were rubber gaskets around the domes (inside on the frame on 3 sides and a flat gasket on the speaker tray) and caulking was used to seal seams where panels and trays met. There are corresponding vents in the frame below the speaker tray. The speaker cover was integral to sealing the inner portion of the domes (I would use an awl to align screw holes and some pressure was required.)
(As an aside, whenever I was installing a single speaker in a mod 12, I always installed it on the passenger side. That way, if a second speaker was installed later, you didn’t worry about sheering off those damn little bolts!)
(As an aside, whenever I was installing a single speaker in a mod 12, I always installed it on the passenger side. That way, if a second speaker was installed later, you didn’t worry about sheering off those damn little bolts!)
I didn't notice that till you mentioned it. Since you got the speaker cover whether you used it or not, my guess is they cut the edges off and used them to secure the dome….scrapped the rest. Worth it if you have already invested in CP-100s.
What do you mean b/c red domes absorb 85% of candlepower, amber 15%? b/c you mean blue clear and red domes? If so, how could a clear dome absorb any candlepower from the bulb if it's clear? Just wondering.
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True, I just know they made selling it that way a factory option (aimed a mechanical sirens) more than the twinsonic did. In theory each side of an SD is independent. That doesn't mean it is a good seal though.
b/c = shorthand for “because”, sorry. Regarding plastic domes (only), red domes absorbed the most, blue somewhere about 60% (but I’ve slept a few times since the last time I checked) and amber 15%. That’s why I used 100w bulbs whenever I could and made sure the proper gauged wire was used (fuses too). Clear domes did not absorb a significant amount of cp.
Regarding clear domes and colored bulbs, that could be a whole n’other thread!
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If you look at the speaker tray of the mod 12, the bolts to secure the speakers were tapped into the extruded rail (front & rear) of the frame. The middle portion of that channel is where the chain ran. It was liberally lubricated with white grease and well sealed against the weather.
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The first TwinSonic configurations in California were Red/Red = sheriffs, police and fire, Red/Amber = fire, Red/Blue = CHP
There's a long story about the fight over Red/Blue in California, for another time.
. . .except that it was. The speaker grille was an option. The basic TwinSonic had a couple of metal straps that secured the inner ends of the lenses. This allowed other accessories to be mounted where the speaker would be, or the use of bell-shaped speakers.
It looked kind of stupid, because the tray still included the plastic isolator that the speaker sat on, making it look unfinished.
Interesting point…FS did accommodate special requests for sizable markets (NYPD 175-H and AeroTwin, Honolulu 174-H, and of course CTS). And the CP series speakers were far more profitable than the TS speakers. I would love to see a FS bulletin.
Plastic speaker trays were used in later production runs. Initially the trays were painted black metal and the aluminum frame was painted black as well (See my photo above).
Good point, I haven't had a lot of twin sonics apart, especially recently. As pointed out below, this may have actually even been a factory option. I know it was with the SD, But I will defer to twin sonic experts on this one.
Start the thread! We would love to heat it! KY had a similar fight back in the 60s and later in the 90s
Well, it's more IDENTIFIABLE in daylight than blue is, and less likely to be mistaken for a reflection of sunlight.