I am setting up an A/V system in an auditorium for powerpoint presentations and video. The video was easy enough, but after I began looking over my options for the sound system I realized I was in over my head.

The room measures 60' x 60' and I am looking to install about 12 in-ceiling speakers with 60-100 watts running to each. What kind of setup would work best for my situation? should I just buy a 12 channel amp and hook up speakers in a normal fashion, or should I consider wiring in series or parallel? And what is a 70 volt system?

Thanks for any assistance, because anything would help.

Sound reinforcement is not a trivial item. Using all of those in ceiling speakers wired in parallel will create some problems. There is time delay involved between the front and back of the room and unless it is accounted for you wil have a lot of phasing issues that will result in unintelligible sound. When doing a project like this, the last thing you want to have to do is to rebuy equipment. You might want to look in your local area for a sound consultant who can help you design the system for the room taking into account whether this is a vocal only system or whether other media might be run through it. Ceiling height, wall and floor treatments as well as furniture in the room all come into play. A more typical setup for that type of room would be front speakers and possibly some rear aimed speakers on the side that are time delayed to coincide with the fronts. For powerpoint presentations, intelligibility is very key so you do not want a lot of phasing issues and you want clear sibilants. Proper EQ of the system is necessary.

A 70 volt system is often used where speakers are being distributed in lots of different rooms or halls. Each speaker has its own output transformer built into it. Essentially it is a high voltage distribution system. It is easier to distribute power at higher voltages over long runs and the 70 volt system was setup to do that. Conversely, high currents and long lead drops make this awkward for 4 and 8 ohm speakers where speakers like to be near their amplifiers.

..Doyle

You might want to look in your local area for a sound consultant who can help you design the system for the room

Agreed. Hire a pro. You'll save in the long run.

Thanks for the direction. I tend to try to do too much myself, so the suggestion will probably garner far better results.

My company could do this for you, shoot me a PM if you are interested in a proposal.