Crown D-150 Service Manual page 38

"APPLICATION NOTE 1
V-T NEEDS OF A LOAD
Evaluating the V-! (volt-ampere) needs of a load: Many loads
exhibit large reactances (or energy storage), which fimits a power
amplifier's ability to deliver a maxirnurn power. If a load stores
energy, which in turn flows back inte the amplifier, itis clear that
the. maximum power efficiency of the system. is. not. being
achieved. Power that flows back into a Hnear amplifier must nec-
essarity be dissipated in the form of heat. A pure reactance is not
capable of dissipating any power; therefore fo drive such a load
would only cause power amplifier heating.
tn practice all loads exhibit some energy dissipation ~~ however
large: their storage characteri 3 ideal
coupling to aity load is one that optirnizes the dissipation
Conmiponent while Minimizing the reactive or Soredeensrgy com
ponent that is seen by the ampiifier's output terrfinats.
tn applications where the iriput is sinusoidal and-of smatl pro:
portional frequency deviation; a relatively stable-load may be
resonantly tuned to preserit a real value of impadarice to the
amplifier.
Any joad, ne matter how complex its behavior, has a V-t operating
range which-may be mapped by the following test.
The maximum voltage and amperage excursions ieitirections ©
in gery ftean penta sie Gee in the
hysterests position. to drive this. load with. this sinusoidal input.
os,
"60 -40 -2000—(O9 2000©« 40 O80
38
Sau SR BRM ULANTaslannn