Sony APM-33W

 How Sony's APM Technology Works

What are the major design features of Sony's Accurate Pistonic Motion speakers? One key characteristic is the use of flat drivers. Flat diaphragms have a major advantage over traditional cone-shaped drivers.  In cone-shaped drivers, the outputs from opposing surfaces of the speaker cone interfere with each other, causing inaccurate frequency response. This is known as the "cavity effect", and it's an inherent abnormality of the cone shape design. Beacuse flat diaphragms like the APM driver are not prone to this type of distortion, you hear a speaker with more linear frequency response.

Honeycomb Construction with Four-point Drive.

To ensure that these compact drivers won't lose their shape when presented with powerful sonic modulations, Sony APM drivers feature an innovative aluminum honeycomb design permits the APM drivers to resist bending - a major cause of distortion in typical paper drivers. Yet the aluminum honeycomb is light in weight for superb transient response.

For these reasons, several speaker manufactures use aluminum honeycomb construction. However, only Sony uses square diaphragms and four-point drive to further eliminate potential nodes of vibration. In this way, distortion is reduced to the vanishing point.

 With all the impressive technology built into the ES Series, it would be a shame to spoil the final enjoyment of the music by using a loudspeaker incapable of matching the system's sonic performance. Yet, that's exactly what would happen with many of the most popular spaekers on the marked today. Very few of them are designed to handle the extremely wide dynamic range that's an important part of PCM, Compact Disc, and beta Hi-FI sound. And almost none can reproduce the full spectrum of the audio frequencies without severe inaccuracies and distortion. Even something as fundamental as clean, uncolored bass response is beyond the capabilities of most speakers.

That's way Sony includes the APM-33W Accurate Pistonic Mption (AMP) loudspeakers as an integral part of the ES series system. They are uniquely qualified to deliver all the exciting sonic benefits that are a part of Sony's advanced technologies.

 Reproducing the particular Attributes of Digital-quality Audio

The APM-33W speakers combine remarkable efficiency and impressive power handling capacity (up to 160 watts) with extended bass response and linear, transparent frequency characteristics. The result is the ability to match the dynamic range of the PCM disgital recordeer, the Compact Disc player, and Beta HiFi videocasssette deck without distortion or overload.

And the low frequency output of the APM-33W is smooth and powerful. This characteristic is especially surprising when you consider the dimensions and appearance of the speaker enclosures - they're small and attractive enough for almost any installation in almost any room.

 The Final Analysis

What do these adbanced APM speakers sound like? Their response is clean, distortion-free, and highly accurate. Their frequency range is also impressive - it extends from 39 to 20,000 Hz , +4, -8 dB. Just as important, the APM-33W speakers can easily handle the most demanding input from s digital source and reproduce it with all its striking clarity, in short, the APM speakers perfectly match our design criteria - they're clean, uncolored, and highly musical.

Specifications

Drivers: 

50 square inches APM-type woofer;

1 square inch APM-type tweeter

Frequency Response:  39 Hz - 20 kHz +4, -8 dB

Sensitivity:  91 dB SPL  1W/1m

PowerHandling Capacity:  80 watts nominal, 160 watts maximum

Nominal Impedance:  6 Ω

Crossover Frequency:  2,2 kHz

Enclosure Type:  Bass Reflex

Dimensions (W x H x D):  315 x 540 x 320 mm (12-1/2" x 21-1/4" x 12-5/8")

Weight:  14,4 kg (31 lb, 10 oz)