Altec Lansing 755E (1968)

A bookshelf speaker system using a 20 cm full-range "Pancake" driver, released in 1968 for the Japanese market.

Overview

The Altec Lansing 755E, also known as the "Medina," is a bookshelf-type speaker system introduced in 1968. Designed specifically for the Japanese market, it was produced by Elektri, an Altec agent, under guidance from ALTEC Sound Laboratory L. T. V Research. The system uses a single 20 cm full-range cone driver from the 755 series, nicknamed "Pancake" for its thin profile. It supports upgrade paths with additional low- or high-frequency units via compatible enclosures and crossovers.

Specifications

Model Rating Type	20 cm cone type full range speaker
System type	1-Way, 1-Speaker, Bassref System, Bookshelf Type
Units used	20 cm Cone Type (755E) full range unit
Frequency characteristic	40 Hz to 15 kHz
Playback frequency band	40 Hz to 15 kHz
Lowest resonance frequency	52 Hz
Impedance	8 Ω
Rated input	20W
Allowable input	15W
Output sound pressure level	95dB/W/m
Output sound pressure level (JIS)	100dB/W
Magnetic flux density	9,000 gauss
Voice Coil Diameter	50mm
External dimensions (driver)	Diameter 213 x Depth 57 mm
External dimensions (enclosure)	Width 358 x Height 596 x Depth 280 mm
Weight (driver)	1.25 kg
Weight (enclosure)	14kg
Enclosure Material	Rigid Homogen + Special Plywood
Exterior finish	Walnut oil finish

Design

The 755E features a thin "Pancake" design with a 20 cm full-range driver using a special cone formed by pressing the cone and center dome together, eliminating anti-resonance strain. The cone has an effective diameter of 17 cm. A cloth edge with good linearity is lightly damped with bis colloid. The driver uses a 50 mm diameter voice coil wound with aluminum ribbon wire edgewise and an "in DACS V-type" magnet made exclusively for the 755E, magnetized to a uniform 9,000 gauss. The frame is aluminum die-cast. The enclosure uses a modified distributed port design with special internal pressure treatment.

Context

The 755E/Medina was developed for the Japanese market under the guidance of ALTEC Sound Laboratory L. T. V Research and produced by Elektri, Altec's agent at the time. It was part of an upgrade ecosystem: low-frequency support could be added using the 416A or 414A drivers (crossover 300–800 Hz) in enclosures like the 846A, 843B, 848A, 847A, or 825A, while high-frequency extension was possible with the 3000H unit (crossover 3k–5kHz).