What makes Analog digital controllers different from digital controllers?

[Greenrid]

Even though I've loved sirens for a long time, I still don't understand why or how analog digital siren controllers are so much more different than digital ones. They both can make the same sounds, and they also do seem to have the same wind up and wind down times, so I'm guessing the controllers make sounds in different ways? I mean, if an analog controller uses a circuit board to make sounds just like a digital one does, wouldn't that make it digital as well?

I also don't fully understand what an amp does in the control box. I know that in some ways amplifies the sound going to the speaker driver, but I don't understand how they work with the control box.

[Model L]

so, "analog" in this case can mean one of 2 things. Fully analog (siratone), or Partially analog (Whelen ESC-864 'analog'). In the case of the former, everything is handled by analog circuitry, a combination of logic gates, resistors, inductors, diodes, and capacitors work together to generate the siren tones & time them all at once. An analog electronic siren is similar to an analog synthesizer, having an primary oscillator that works to make the siren tone and a second, low frequency oscillator that modulates the tone to produce signals such as wail, or attack. Now, in the case of the latter, an ESC-864 has a microprocessor that controls the sirens functions, essentially a small computer. It controls things such as signal timing and duration, which signal, and can even play back prerecorded messages. The siren tone itself however, is still generated with similar circuitry to the full analog sirens. The first generation of ESC-864 is very much a hybrid between the 2 different technologies. Indeed there were a few synthesizers that also took advantage of this, allowing saved presets while retaining the analog based tone generation.
Finally, fully digital sirens are, as the name says fully digital. the tone generation is handled by the microprocessor in its entirety, and there is little to no analog circuitry involved. This allows for massive customization, as can be seen with the Ultravoice controller, allowing the user to program nearly any toneset imaginable, within some limitations of course. They also support playback of high quality audio files for voice announcements.

All of these controllers have one thing in common. They output a "low level" signal. If you try connecting a speaker driver directly to this signal, at best it would be very quiet. At worst, it draws so much current it breaks a component on the control board. Here's where the amplifier steps in. The amplifier takes in the signal from the control board, and using a transformer and some other circuitry, steps the low voltage, low current signal up to a high current, high voltage signal that is then sent to the speaker driver.