Trying to characterize amplifiers or loudspeakers only by power ratings is akin to trying to completely characterize a person by a photograph. There is always much more than meets the eye.
Few subjects generate more confusion in the audio world than power. There is a very good reason for this—it’s a confusing subject, and one that can easily fool our intuition.
Most of us are on a power trip—our attitude is that “more is better.” We want bigger amplifiers and more “powerful” loudspeakers so that our sound systems will be louder.
In fact, power ratings are often the main (or only) criteria considered regarding amplifiers and loudspeakers by equipment buyers. But here, let’s take a bigger look at the role of power in sound systems, hopefully without diminishing or overemphasizing its importance.
Power ratings are only one piece of a larger puzzle. Trying to characterize amplifiers or loudspeakers only by power ratings is akin to trying to completely characterize a person by a photograph. There is always much more than meets the eye.
To form our understanding about power, let’s initially forget about sound systems (with the exception of an occasional reference) and consider power in light of other ways that we use it in daily life.
We will begin with some basics. Power is both generated and consumed. From the perspective of generation—more is better. We always want to have more power available than what we need. From the perspective of consumption—less is better. If a task can be accomplished using less power, we save money since power generation usually costs money.
Power is wasted if it is not doing something useful. In sound systems, amplifiers and loudspeakers are both consumers and generators of power. The amplifier consumes power from the electrical service and generates power to drive the loudspeaker. The loudspeaker consumes power from the amplifier and generates sound power into the room.
Rating methods are used to describe both power generation and consumption (both are in watts). Great care must be taken to be sure which one a power rating is describing, since a larger rating may be better for a power generator, but a smaller rating may be better for a power consumer.
Universal Principles
No, this isn’t a self-help infomercial—it’s a discussion of some of the properties that affect the flow of power. Power principles are analogous in electrical and mechanical systems. Mechanical examples are more prevalent in our everyday lives, so it is easier to look at power from that vantage point.
We begin with energy. In fact, everything began with energy. Energy sources include power plants, automobiles, locomotives, bombs, animals and humans, and less-obvious sources such as plants, water, wind and even garbage.
All energy sources must get their energy from somewhere else, making the “big picture” question a religious one (we won’t go there). Most of the energy on planet Earth comes from the sun, the ultimate power source in our physical sphere of existence.
