Specifications

Signal Processing

Here’s a hypothetical example of what to look out for. An APL-12

might be set up outdoors in 85°F (29°C) temperature with sunlight shining

partially on the rear panel. Let’s assume it is tested during a 30-minute sound

check and all is well. Later that day, the ambient temperature rises to 99°F

(37°C) and the sunlight is now shining directly on the rear of the loudspeak-

er. The show starts, featuring dance tracks with no pause between song titles.

Under such extreme conditions, it is entirely possible that after a period of

service, the loudspeaker will shut off to protect itself from excessive heat.

Problems, such as the one described above, can be avoided by shading the

heat exchanger from direct sunlight.

(1) Basic Concept

The APL-10/12 speakers use a highly-advanced signal processor contained

entirely within the unit. The processor provides the functions of an asym-

metrical electronic crossover (36 dB/octave low-pass and 24 dB/octave high-

pass), fixed equalization to compensate for driver/enclosure anomalies, and

advanced protective limiting circuits. It also provides a low-frequency align-

ment circuit that acts synergistically with the enclosure’s ports. This serves to

extend the bass response well below that of a conventional enclosure of a

similar size. All circuits in the audio path utilize the highest quality, most up-

to-date semi-conductor technologies available today.

The processor is the key to the extraordinary sound quality of the loud-

speaker system. Unlike generic crossovers, either digital or analog, the APL

processor was carefully designed in tandem with the drivers and the enclo-

sure, to provide optimum performance.

(2) Driver Protection

The APL-10/12 speakers utilize a special, highly-evolved set of limiter param-

eters and controls. Multiple limiters are used simultaneously with attack,

release, integration time, and slopes that have been carefully matched to the

individual speakers thermal and mechanical limits over time.

All of this occurs without compromising dynamic range or otherwise unnat-

urally compressing the program material. The protection circuits only act

when the drivers would otherwise be damaged and, therefore, are excep-

tionally transparent. They are effectively “out of circuit” when below the

threshold of engagement. The result is extremely clean sound quality, with

effective protection of potential damage to the drivers under abusive

conditions.