This customer got a building with some ceiling mounted speakers in it. They appear to be 70 volt. Can I take a small amp with 70 volt output; hook up the speakers and put a tone thru the amp just to see if they all work? no gonna drive it hard. just wanna check them.Any thoughts?
You could use a normal amp to do that test. The level may be lower than what you would normally expect from the amp-due to the higher impedance.
So by your statement-I assume there is no amp in place.
To me the FIRST thing I would do would be to do an impedance SWEEP-NOT a DC resistance reading.
This way you can get an idea of what the total load presented to the amplifier would be-assuming the speakers are all properly tapped.
That is the only way you have to get an idea of what size amp you should use.