Audio Systems: Fire Dept. Announcement System, fire department staff, speaker location

Question
I have been placed in charge of obtaining and installing a announcing system in our fire dept. I have the receiver and it has an audio output. The manufacture recommends to run the audio through an amp before sending it to the speakers. We would like to place 5 regular speakers throughout the station and one loud speaker in the apparatus bay. I have no clue of what kind of amp and speakers that would work for this setup. Thanks for your help.
Jeremy

Answer
You have some homework to do.

There are two methods you can employ.

ONE:  A single commercial amplifier that has what is called 70v or 25v speaker outputs.  Then, each speaker has a 70v or 25v transformer mounted on it and taps on the secondary of the transformer for the audio level you want the speaker to have.   For example, noisy or large areas need higher sound output than an office or quiet area. In this method you will need to run the wires in conduit - probably, depending on the building code for your facility - and the speaker/transformers are more expensive that option TWO.  You can check out such systems at Radio Shack and other commercial system suppliers.

TWO:  An individual amplifier for each speaker.  That way each speaker can be individually adjusted with the volume control of its amplifier.  This is the best method because the speakers can be economical and the wire runs do not need to be in conduit because they are low voltage, low impedance lines.  You can buy amplifiers very inexpensively now days and speakers, depending on how big the coverage area is are not so expensive.  

All in all the two methods could be equal in cost.   Method ONE should probably require the use of a professional installer.  Changing the audio levels once the system is installed is possible, but requires a change of the taps on the transformer at each speaker location.  Method two can be done by the fire department staff and changing the sound level for the different areas is easily accomplished by adjusting the volume control of each amplifier.

Let me know if you have further questions.

C

PS:  FOr the amplifiers, you can use stereo for two channel operation or even a 5 channel amplifier from an audio shop.