FOSTER/FOSTEX GZ-77

Commentary

A speaker system designed around an edgeless woofer based on the SLE system.

A 20 cm cone type woofer using SLE method is mounted in the low range.

In the SLE (Super Linear Long Excursion) system, the mechanical suspension (edge) is removed from the outer circumference of the cone paper, and excellent linearity is obtained. In addition, there is no valley in the mid-range characteristics caused by abnormal vibration of the edge or abnormal sound in the low range, and excellent low range reproduction is possible. In addition, a balanced double damper mechanism is adopted in which two upper and lower positions of the winding part of the voice coil are fixed, and the symmetry of the piston motion of the cone paper is enhanced.
In the SLE woofer, by eliminating the edge and adopting a double damper mechanism, the stroke of the vibration system is twice that of the conventional one, thereby realizing excellent input resistance despite the 20 cm aperture.

The SLE system woofer unit is equipped with an acoustic low-pass filter.
There is a gap of 1 mm between the cone paper and the outer ring frame. If this part is replaced with an equivalent circuit, it works like a port in a bass-reflex cabinet with a resonance point at a certain frequency. The acoustic low-pass filter is designed so that the resonance frequency is below the audible frequency. Therefore, this filter has a sufficiently large attenuation characteristic in the audible frequency, the gap can be completely ignored, the sound pressure before and after the cone paper does not short-circuit through the gap, and there is no sound pressure drop.

The cone paper of Woofer is made of pulp material with sufficient rigidity, and special material with large internal loss is added for composite molding, which increases internal loss while maintaining rigidity.

A 5 cm dome type skoker is installed in the middle area.
A 2.5 cm dome-shaped tweeter is installed in the high-frequency range.

Equipped with 3-step switching type level control for middle and high frequencies.

The enclosure uses a bass reflex system.
The exterior is finished with a walnut open pore finish, and the wood is completely hardened by allowing the coating material to penetrate deeply into the wood while taking advantage of the taste of wood. This gives a more moist and glossy finish than conventional enclosures.

One touch type is adopted for the rear terminal.

* The above color photograph seems to be a prototype, and the level control is not 3-step switching type.

Model Rating

Method	3-Way, 3-Speaker, Bass reflex system, Bookshelf Type
Units Used	For low band : 20 cm cone type For Middle Area : 5 cm Dome Type For high-pass : 2.5 cm dome type
Impedance	8 Ω
Frequency characteristic	30 Hz to 20 kHz
Output sound pressure level	89 dB (New JIS Standard) 95 dB (Old JIS Standard)
Input	160W (Music Power)
Crossover frequency	700 Hz, 5 kHz
Level control	Medium range, high range, 3-step switching type
External dimensions	Width 400x Height 685x Depth 300 mm
Weight	23kg