ESPRIT APM-8

Commentary

This is a 4-way floor type speaker system that uses the APM (Accurate Pistonic Motion) method developed by SONY over three years.

807 cm in the lower range²A honeycomb sandwich diaphragm made of aluminum skin is driven at four points by four magnetic circuits and voice coils.
For the magnetic circuit, slits and grooves are cut in the center pole plate to hold the eddy current and reduce distortion.
In addition, the voice coil uses a oxygen-free copper ribbon line edgewise winding.

144 cm with a honeycomb sandwich diaphragm made of carbon fiber sheet skin for the middle and low band²Planar unit has been adopted.
A low-distortion magnetic circuit is adopted like the woofer. The voice coil wire is edgewise wound with pure aluminum ribbon wire to reduce weight. The mica bobbin with high Young's modulus reduces loss when transmitting force generated by the magnetic circuit to the diaphragm.

24 cm for middle and high areas²Plane unit is adopted.
This unit uses a honeycomb sandwich diaphragm made of carbon fiber sheet skin, and the magnetic circuit and material composition are the same as those of the middle and low frequency units.

5.8 cm in the high range²Flat type tweeter is adopted.
Honeycomb sandwich diaphragm made of carbon fiber sheet skin is adopted for the diaphragm, and magnetic circuit realizes magnetic flux density of 21,000 gauss by using Permendur for pole piece.
In addition, the voice coil is made by edgewise winding of pure aluminum ribbon wire on the mica bobbin to improve rigidity and efficiency.

In order to suppress sound degradation due to mechanical resonance, all capacitors and inductors in the network and internal wiring are molded with high pressure of acoustic material SBMC with high internal loss.
In addition, extremely thick oxygen-free copper foils are used for the printed circuit board, oxygen-free copper wires are used for internal wiring, and parallel wires are frequently used to reduce loss and coloring.

The enclosure is a high-density particle board with an internal volume of 200L and a dead weight of 60 kg.
The radiation frequency of each board is calculated by Fast Fourier Transform. By controlling the thickness of the board and the material of the reinforcement, the radiation frequency is restrained from overlapping, and by minimizing the coupling of each plane as much as possible, the noise is suppressed.

Model Rating

Method	4-Way, 4-Speaker, Bass Reflex System, Floor Type
Unit	For low band : 807 cm2Plane type For middle and low band : 144 cm2Plane type For Middle and High Areas : 24 cm2Plane type High-pass : 5.8 cm2Plane type
Playback frequency band	25 Hz to 30000 Hz
Output sound pressure level	92dB/W/m
Maximum output sound pressure level	119dB/m
Impedance	8 Ω
Rated maximum input	150W
Instantaneous maximum input	500W
Crossover frequency	320 Hz, 1250 Hz, 4500 Hz
Level control	+ 0 dB, -6dB continuously variable
External dimensions	Width 650x Height 1105x Depth 450 mm
Weight	102kg