But, if you're new around here, you're probably visiting this lonely corner of GBfans (though not as lonely as Giga Meters) in search of or to talk about sound effect files for the Ecto-1 siren!
Well, this thread right here is your very own one-stop-shop for all your Ecto siren needs!
First of all, the siren you hear coming from the Ecto-1 in the movies is not a real, production siren. At least we're pretty sure it isn't. As far as we know, it was a studio-created sound effect that was then applied to the movie in post-production.
The "Default" Siren
You can find mp3 files of the siren that have been edited off the movie here: http://www.hprops.com/sounds/
With that link you can also find various remixes or unlooped samples of the siren for your own use in fanfilms or effects tests or whatever you'd like. Also, a wide range of proton pack sound effects.
The "Montage" Siren
GB1 features another siren that is only heard during the montage sequence. It is faster and has a higher pitch, but sounds fairly similar. This siren is almost never associated with the Ecto-1 even though it was the effect used in one of the primary Ectomobile scenes in the film. It was largely ignored until recently, when 69428scj edited together his own version of the sound effect and posted it here: http://www.zshare.net/audio/64557438e0a85f72/
If you're building an Ecto, it's definitely a must-have sound effect, if only for making your neighbors dogs head explode.
Application of the Siren to Your Vehicle
Since the siren is not an actual device and it only exists in sound file form, it can be kind of tricky to make your home-made Ecto-1 capable of blasting it out the roof. The most commonly-used method of applying the sound effect is through a CD or MP3 player which then feeds into an amp and then into roof-mounted speakers. You can use a normal Radio Shack loudspeaker or stereo speakers or, whatever really. Some users have even put the sound effect on their phone and jacked into a set of speakers to great effect. I use a 750-watt amp hooked to a set of four 8-inch weather-proof marine speakers and have had fantastic results.
The benefit of this method is that you can play other sounds out of your roof rack. The Ghostbusters theme or "Savin the Day" or whatever you damn well please. In my experience, "Thriller" is usually a hit on Halloween.
There are other methods currently being developed by other users. A good example would be Replica Props' siren sound board, which can be wired directly into throw switches to play the wind up and wind down sequences
So yeah, there you have it. Discuss!