The formula that we described for arriving at our minimum RMS power figure assumed that the loudspeaker radiated its sound in all directions away from the source. In truth, some speakers don't. The best loudspeakers for small-room listening are direct-radiator types, simply because they do radiate the sound over a broad area. But horns. which usually behave best in very large rooms, tend to direct most of their output forward, so a higher proportion of the radiated sound goes directly toward the listener. This would tend to reduce the power requirement even more for a horn-loaded system, but the high efficiency of the average horn puts its power requirement so low to begin with that it is pointless to quibble over an extra watt or two, even though this may represent a doubling or halving of the computed figure.
An orchestral crescendo, or a full choral passage, contains transients that are fully 10dB higher than the average volume of the sound, as measured by a sound level meter. A 10dB increase in level represents a 10-fold increase in power, so how can we possibly hope to cope with this sort of thing? Fortunately, we don't have to. Recording studios and broadcast stations use peak limiters to keep these huge transients out of the received signal, and tape recorders have their own built-in limiting action. Transients are high- frequency phenomena, and tape will saturate instantly if a strong treble impulse is fed to it. The result is a shearing-off of the peak, and if the overload doesn't last too long, this won't cause any more audible disturbance than a good peak limiter.
An orchestral crescendo, or a full choral passage, contains transients that are fully 10dB higher than the average volume of the sound, as measured by a sound level meter. A 10dB increase in level represents a 10-fold increase in power, so how can we possibly hope to cope with this sort of thing? Fortunately, we don't have to. Recording studios and broadcast stations use peak limiters to keep these huge transients out of the received signal, and tape recorders have their own built-in limiting action. Transients are high- frequency phenomena, and tape will saturate instantly if a strong treble impulse is fed to it. The result is a shearing-off of the peak, and if the overload doesn't last too long, this won't cause any more audible disturbance than a good peak limiter.

