Monoprice 14886, Руководство пользователя, Страница: 8 / 16

8
CONSTANT VOLTAGE VS LOW IMPEDANCE SPEAKER
SYSTEMS
A constant voltage speaker system differs from a traditional low impedance (e.g., 8-
ohm) speaker system in that it uses a step-up transformer at the audio source to raise
the voltage and lower the current on the transmission line. At the speaker end, a step-
down transformer converts the signal back to a normal speaker level voltage. This
reduces power loss during transmission, which allows for the use of longer speaker wire
runs using smaller gauge wire.
Additionally, a constant voltage speaker system allows for the use of multiple speakers
on each channel, without the need for complicated impedance calculations and
configurations. In a constant voltage system, all speakers on a given channel are
connected in parallel and the complicated impedance calculations are replaced by
simple wattage calculations.
For example, if you want to connect two speakers per channel in a traditional 8-ohm
speaker system, you must either connect them in series, which results in an overall 16-
ohm impedance, or in parallel, which results in an overall 4-ohm impedance. In the first
case, the 16-ohms impedance effectively halves the output power of your amplifier,
resulting in lower overall volume levels. In the latter case, the 4-ohms impedance means
that your amplifier will have to work harder and must be rated as stable at 4 ohms.
Adding a third speaker to the mix would complicate it further, producing either a 24-
ohm or 2.67-ohm overall impedance. Note that very few amplifiers are stable under 2-
ohm loads, so that is usually not an option.
On the other hand, with a constant voltage system, you consider first the RMS output
wattage of the amplifier. This should be reduced by 20% to compensate for insertion
loss. Each individual speaker on a given channel is set to a value such that the total does
not exceed the rated power, less 20%. You do not need to worry about making the
total as close as possible to the limit; just ensure that the total does not exceed the
limit. For example, with the 120-watt model, the total load from speakers should not
exceed 96 watts.