Technics SB-MX7

Commentary

This 3-way speaker system uses MICA TMD vibration plates for all units.

As a natural material, mica is lightweight and approximately three times more rigid than aluminum. Moreover, since it has high internal loss, it has a characteristic that there is no inherent squeal which is often found in high-rigid materials.
The SB-MX7 woofer uses a composite mica diaphragm. Natural mica is the main component, natural pulp and self-adhesive novolac fiber are mixed together. Thermosetting resin is added to the mixture, and the mixture is heated and pressed in a precision metal mold.
In addition, Pure Mica is used as the diaphragm material for the mid-range and tweeter. Pure Mica is made by refining high-quality natural mica to a size of 200 μ m and heat-curing it with a small amount of binder. It realizes a higher specific elastic modulus and internal loss than titanium, and obtains a wide piston motion band.

The woofer and mid-range diaphragm structures use TMD (Technics Monocoque Diaphragm) developed from hundreds of simulations and prototypes.
In the TMD, the cone and center cap, which were separate pieces in the conventional cone type, are integrated into a single structure. In addition, by adopting a unique shape selected from computer simulation, the rigidity is dramatically improved, thereby realizing a piston motion range twice that of the conventional cone type.

A 32 cm cone type woofer is installed in the low range.
This unit uses a composite mica & TMD diaphragm to achieve a piston motion range of 2.5 kHz. The magnetic circuit uses a large magnet, one of the largest in its class, and a four layer long voice coil made of polyamide fused wire to achieve excellent power linearity.
In addition, the frame is made of aluminum die-cast with a highly rigid design to eliminate unnecessary vibration.

The mid-range is equipped with 10 cm cone type mid-range.
By adopting Pure Mica & TMD diaphragm and directly driven by φ 45 mm voice coil, piston motion band of 10 kHz is realized. In addition, large magnet of 90 mm outer diameter and 15 mm thickness is used for magnetic circuit, and high input resistance is realized by adopting voice coil with good heat radiation.
Aluminum die-cast is used for the frame.

A 2.5 cm dome type tweeter is installed in the high range.
A high frequency reproduction band of 45 kHz (-16dB) is achieved by using pure mica for the diaphragm. In addition, the equalizer on the front of the dome diaphragm has been eliminated to improve the quality of high frequency omission.

The network section is designed to cross the mid-range at a frequency as low as 250 Hz to increase the reproducibility of female vocals.
In addition, high-quality parts are used. Metalized polyester capacitors with excellent high-frequency characteristics and large electrolytic capacitors for acoustic use are used for capacitors. Ferrite cores developed specifically for audio are used for choke coils. oxygen-free copper is used for internal wiring materials. Network elements are directly connected to improve acoustic resolution and physical characteristics.
The network circuit eliminates crosstalk by making the woofer / mid-range / tweeter a completely independent two part configuration.

The enclosure consists of a cross-bridge and a cross-enclosure with a reinforced partition plate built into the center of the enclosure, thereby reducing unnecessary radiation noise caused by vibration of the enclosure walls without increasing unnecessary weight.
In addition, the 30 mm thick front baffle is processed into a round baffle shape to prevent adverse effects due to diffraction of sound waves.

Model Rating

Method	3-Way, 3-Speaker, Airtight Type, Bookshelf Type
Units Used	For low band : 32 cm cone type For Medium Range : 10 cm Cone Type For high-pass : 2.5 cm dome type
Playback frequency band	30 Hz to 45 kHz -16dB
Crossover frequency	250 Hz, 2.5 kHz
Impedance	6 Ω
Output sound pressure level	91dB/W/m
Allowable input	240W(MUSIC) 120W(DIN)
External dimensions	Width 380x Height 670x Depth 353 mm
Weight	28kg
Sold Separately	Dedicated Speaker Stand SH-377 (2 pcs 1 set, ¥ 30,000)