TECHNICS SB-G90M2

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Point Sound Source Speaker System
One ideal in reproducing sound with full spatial expression is to ensure that the wave-fronts emitted from the speaker units are aligned at any listening position, i.e., providing a point sound source. While inheriting the linear phase concept, the SB-G90 has newly developed two-way coaxial cone units (including mid-range and tweeter) targeting high-speed reproduction with enhanced high sensitivity.

Phase Precision Driver (Coaxial 2-way Speaker Unit)
A lightweight, high-rigidity anodized aluminium dome diaphragm is used for the tweeter diaphragm. The driver reproduces a wide frequency range up to 100 kHz by using a new dome shape optimized through simulation, as well as achieving greater uniformity in phase characteristics by using a phase plug. In addition, the SB-G90 uses high-linearity-drive underhung voice coils, the magnetic gaps of which have had magnetic fluid injected to suppress temperature rise, thereby ensuring superior power linearity. These features provide reproduction of the high-frequency range with superb detail and beauty.
As with the tweeter, the mid-range also uses an anodized, lightweight, high-rigidity aluminium cone diaphragm. The magnetic circuit achieves low distortion and enhanced drive power by using large magnets, copper caps, and high-linearity-drive underhung voice coils. Also, the support structure provided by the tough die-cast frame has resonance-dispersing arms, thereby thoroughly eliminating even the slightest unnecessary resonant sound. These features enable mid-range reproduction with excellent precision and response.
In addition, the mid-range diaphragm uses a cone shape in which its sound generation centre in the axial direction is closer to the sound generation centre of the tweeter, and the position of the axial direction of the dome tweeter placed in the centre of the mid-range diaphragm is precisely adjusted, thus achieving linear phase reproduction by integrating the sound in each range without time lag. Also, the inside end of the mid-range diaphragm has a smooth shape so there is no deterioration of tweeter sound characteristics, with the diaphragm being constructed to deliver the sound emitted from the tweeter directly to the listening space. This reproduces mid-range and highs with superb precision and response, as well as excellent clarity in sound imaging.

Illustration for structure of speaker unit
BDMA (Balanced Driver Mounting Architecture)
With the conventional method of mounting a speaker unit to a baffle, the centre of gravity of the speaker unit was located away from the support points, and so the force acting on the voice coil when driving the speaker produced vibration of the entire speaker unit. This produced distortion in the sound waves generated from the diaphragm, resulting in deterioration of sound quality. In addition, mounting the speaker unit to the baffle is a configuration that easily transmits vibration of the speaker unit itself to the baffle, and so unnecessary vibration sound was produced from the baffle, again with deterioration of the sound quality.

With Balanced Driver Mounting Architecture, the speaker unit is mounted to a sub-baffle installed inside the cabinet at the speaker unit's centre of gravity, suppressing vibration of the speaker unit. Also, because the speaker unit is not mounted to the baffle on the front, transmission of unwanted vibration from the speaker unit to the baffle is suppressed. This makes it possible to reduce distortion in the sound waves generated from the diaphragm and reduce unwanted vibration sound from the baffle, for reproduction of a sound field with excellent sound imaging featuring impressive realism and clarity, allowing visualization of the fine details of each and every sound.

Concept of Balanced Driver Mounting Architecture
16cm Low-distortion Long-stroke Woofer
The woofers have features such as double magnets producing robust drive power, and magnetic circuits with high-linearity-drive overhung voice coils, copper rings, and aluminium short rings. This newly developed long-stroke unit achieves low-frequency reproduction with wide dynamic range as well as excellent low distortion and response even for a large excursion. Also, the support structure of the tough die-cast frame disperses resonance, thereby thoroughly eliminating even the slightest unnecessary resonant sound. And, a lightweight, high-rigidity anodized aluminium cone diaphragm is used to ensure uniformity in tone with the mid-range and high frequencies.
These features reproduce robust, powerful bass.

Graphic of 16cm Low-distortion Long-stroke Woofer
High-quality Network Circuit
The high-precision network circuit was created through repeated listening and redesign, in order to maximize the performance of each speaker unit and achieve well-balanced sound. High-quality parts, such as a polypropylene film capacitor, an air-core choke coil, and OFC wire used for connection were carefully selected by examining their properties.

In order to prevent sound vibration emitted into the cabinet by the speaker units from affecting the network, the network is installed in its own compartment separated from the speaker units, thereby achieving reproduction of sound providing an atmospheric feel.

High-rigidity Cabinet
Cabinet strength is ensured inside the cabinet by using a cross construction with sub-baffles to which the speaker units are mounted and horizontal reinforcing panels. A separate sub-baffle is used for each speaker unit, which minimises sympathetic vibration between speaker units. In addition, differentiated use of two kinds of absorbent acoustic materials with optimal placement inside the cabinet suppresses internal standing waves and reduces incidental sound due to reflection in the cabinet.
Also, multiple polyurethane (PU) coatings on the cabinet surface dampen cabinet vibration, thereby thoroughly suppressing the production of unnecessary sound. These features reproduce a vast sound field with excellent sound imaging.