In article
,
klem kedidelhopper wrote:

I need to install a 60 Watt paging amplifier on a job. The maximum
load at this time is 42 Watts, however we need to have a slight amount
of room to move in the future. So I felt that 60W unit would be a good
cushion. I currently have in the shop a nice Technics 100 Watt mono
amp that I rebuilt and have no plans for. I would really like to sell
this to the customer to use for this application. The problem is
though it does not have the 70V output that I need.

Klem-

You may be able to do what you want, but selling it makes you liable if
anything catches fire!

Suppose you connect your 100 Watt Technics amp directly to the
distribution system. Maximum RMS voltage out of a 16 Ohm output would
be 40 Volts. For a 70.7 Volt system, maximum power would be somewhat
less than 100 Watts before it starts to clip.

Using a 100 Watt (or 60 Watt) constant voltage transformer connected
backwards to the amp may work for your purposes, but there might be a
penalty in frequency response. Try it and see how it sounds.

About forty years ago I did something similar with an amplifier and some
constant voltage transformers. It was a jury-rigged background music
system using an old Eico FM tuner and Heathkit monaural tube-type HiFi
amplifier. Speakers were mounted in cardboard boxes. It worked and
sounded quite well, considering!

Fred