Why 100v line?
Let's say you've been asked to provide a PA system for a large outdoor fete. You only need it for speech and
possibly low-level background music, but you need a lot of speakers to cover the area and they're all some
distance apart. This would present an absolute nightmare if you wanted to use a 'standard' low impedance
PA amp and speakers. For a start, the distances involved between amp and speakers are pretty large,
hundreds of metres or more. Sure, you could run a low impedance system, but you'll need to compete with
extremely high losses in the cables. Either you put up with stupidly large voltage drops, or you use very bulky
cable. Either way, its kludgy at best and very inconvenient. That's assuming your amp is even happy with
driving such long lengths of cable.
That's just the start. Now imagine you need 15 speakers to cover the area. How are you going to wire these
and still present a suitable impedance load to the amp? You could do it by wiring in series-parallel
combinations, but the wiring would soon become a rats nest, and for temporary events you want the
installation to be as quick and painless as possible to set up and tear down.
What's the difference?
In a 100v line system, the amp and every individual speaker is fitted with a transformer with a high
impedance primary and low impedance secondary. The primary is the 100v line side, and the secondary is
connected to the speaker driver. If you're even slightly familiar with Ohms law, perhaps you're starting to see
the advantages here already. With this system we increase the line voltage in a tradeoff to decrease current,
whereas a standard low impedance system operates at high currents and relatively low voltages.
Why 100v line?
Let's say you've been asked to provide a PA system for a large outdoor fete. You only need it for speech and
possibly low-level background music, but you need a lot of speakers to cover the area and they're all some
distance apart. This would present an absolute nightmare if you wanted to use a 'standard' low impedance
PA amp and speakers. For a start, the distances involved between amp and speakers are pretty large,
hundreds of metres or more. Sure, you could run a low impedance system, but you'll need to compete with
extremely high losses in the cables. Either you put up with stupidly large voltage drops, or you use very bulky
cable. Either way, its kludgy at best and very inconvenient. That's assuming your amp is even happy with
driving such long lengths of cable.
That's just the start. Now imagine you need 15 speakers to cover the area. How are you going to wire these
and still present a suitable impedance load to the amp? You could do it by wiring in series-parallel
combinations, but the wiring would soon become a rats nest, and for temporary events you want the
installation to be as quick and painless as possible to set up and tear down.
What's the difference?
In a 100v line system, the amp and every individual speaker is fitted with a transformer with a high
impedance primary and low impedance secondary. The primary is the 100v line side, and the secondary is
connected to the speaker driver. If you're even slightly familiar with Ohms law, perhaps you're starting to see
the advantages here already. With this system we increase the line voltage in a tradeoff to decrease current,
whereas a standard low impedance system operates at high currents and relatively low voltages.
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