Specification trio of TRIO LS-77

TRIO LS-77
¥ 33,000 (1 unit, around 1976)

Commentary

A speaker system combining a coaxial unit and a passive radiator.

The unit is equipped with a 25 cm coaxial unit combines 25 cm cone type woofer and radial horn tweeter.
As a single unit, a radial horn with an output level close to 100 dB is used for the high frequency band. This radial horn is coaxial with the woofer, so the sound source is close to a point sound source, and the directional characteristics are broad and clear sound image localization is realized.

The woofer diaphragm is made of corn paper containing Canadian Forest and cellulose rich pulp at a ratio of 9 : 1.
The support part uses a free edge that eliminates low-frequency distortion by coating cotton with rubber. The damper uses cotton impregnated with phenol.
Uses a large 110 φ magnet.

The exponential horn used in the high-frequency horn is die-cast, and the back side of the horn is covered with rubber strapping. The equalizer section is also made of zinc die-cast with high machining accuracy. This reduces the gap between the diaphragm and the equalizer, thus improving the high-frequency limit.
A polyester diaphragm with evaporated aluminum is used for the diaphragm, a 25 mm large-diameter voice coil is used for the magnetic circuit, and an internal Alnico V magnet with low leakage flux is used for the magnet.

It is equipped with a 25 cm cone type passive radiator that drives the cone paper using the sound pressure change inside the enclosure caused by the woofer. By combining the woofer and passive radiator, the area is theoretically equivalent to that of a 35 cm diameter woofer, and the reproduction capability in the low frequency range is enhanced. In addition to simply supplementing the output of the woofer, the third harmonic distortion between 40 Hz and 200 Hz is minimized.

The passive radiator is equipped with a weight disk, and you can control low-frequency characteristics according to the condition of the room.
You can adjust the low-frequency level by installing an optional boosting disk or damping disk (sold separately).

Equipped with continuously variable level control.

It seems that there were 2 kinds of exterior, wood grain finish and black finish.

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Model Rating

Method	2-way, 1-speaker, passive radiator system, bookshelf type
Units Used	For all bands : coaxial 2 way For low band : 25 cm cone type For High Frequency : Horn Type Other : 25 cm cone type passive radiator
Frequency characteristic	40 Hz to 20 kHz
Max Input	60W
Output sound pressure level	93dB/W/m
Crossover frequency	4kHz
Level control	± 8 dB continuously variable
External dimensions	Width 330x Height 600x Depth 300 mm
Weight	15.5kg
Sold Separately	Weight Disk PW-77 (4 disks per set, ¥ 2,000)