Technics SB-MX200

Commentary

A floor-type speaker system that uses pure mica for all units and suppresses unnecessary vibration and radiation.

Pure mica is used for the diaphragm material of all units.
As a natural material, mica has a sound velocity of 6700m/s and a specific gravity of 1.9. It is lightweight and has bending rigidity about three times that of aluminum. Moreover, because it has a high internal loss, it has no inherent squeal, which is often found in high-rigidity materials, so it has excellent characteristics as a diaphragm material.
Pure Mica used in all units of SB-MX200 is made of carefully selected high-quality natural mica finely pulverized to φ 200 μ and heat-hardened into the shape of a diaphragm with a metal mold. It has a higher specific elastic modulus and internal loss than titanium, and realizes a wide range of piston motion.

A 27 cm cone type woofer is installed in the low range.
This unit uses TMD (Technics Monocoque Diaphfor the diaphragm shape of this unit. The cone part and the center cap part, which were separate pieces in the conventional cone type, are integrated into the TMD structure. Moreover, the TMD has a unique shape determined by computer simulation. As a result, the rigidity is dramatically improved and the piston motion range is expanded to about twice that of the conventional cone type.
In addition, the pure mica vibration plate is coated with lacquer coating to suppress unnecessary vibration and acquire natural sound, and realizes a range of more than 3.5 kHz for piston motion.
The magnetic circuit uses a strontium ferrite magnet with a diameter of 145 mm and a thickness of 20 mm for the main magnet, and barium ferrite with a diameter of 120 mm and a thickness of 15 mm for the cancellation magnet. Both the improvement of force factor and low magnetic leakage are achieved. The voice coil uses a long edgewise voice coil with a winding width of 24 mm made of polyamide fusion wire. Heat resistance of 250 ℃ is achieved, contributing to high input resistance.
The frame uses a zinc die-cast frame designed to disperse resonance and a sealed frame with a rubber gasket covering the exterior of the frame to eliminate interference with reproduced sound due to unwanted radiation.

The mid-range features a 6 cm dome mid-range.
Similar to Woofer, it uses a dome type diaphragm made of pure mica coated with Japanese lacquer. It is driven by a φ 60 mm edge-wise voice coil to obtain a piston motion band of 10 kHz or more.
The magnetic circuit uses barium ferrite with a diameter of 130 mm and a thickness of 20 mm for the main magnet and a diameter of 110 mm and a thickness of 15 mm for the cancellation magnet. It also uses a copper ring and a short voice coil that prevents the voice coil amplitude from coming out of the top plate. This reduces distortion.
In addition, the aluminum die-cast panel is designed to be vibration-proof by attaching a vibration-proof ring made of fine fibers. In addition, the outer circumference is shielded with rubber gasket, and attention is paid to the sound absorbing material to eliminate the influence of unnecessary radiation.

A 2.5 cm dome type tweeter is installed in the high range.
This unit achieves high-frequency characteristics of 45 kHz (-16dB) by coating pure mica with diamond using plasma CVD method, and uses neodymium magnet with strong magnetic characteristics for magnetic circuit.
In addition, as in the mid-range, we have bonded aluminum die-cast panels with vibration suppression and quantity in order to suppress unnecessary radiation, etc., and the outer circumference is also shielded by rubber gas, so that high sound with excellent SN is obtained.

The network of each unit is divided into three parts in order to suppress mutual interference.
The choke coil is made of a large low-strain ferrite core with a high magnetic saturation point. The choke coil is wrapped with an extremely thick LC-OFC Class 1 cable and treated with a hardening varnish to prevent vibration. The choke coil is made of a large electrolytic capacitor for acoustic use or a polyester film capacitor depending on the application. The wire is made of LC-OFC Class 1 cable covered with a vibration-proof coating.
The choke coils and network boards of this network are attached to the enclosure via anti-vibration material to block unwanted acoustic feedback.

Separate baffle is used for the front baffle.
In the separate baffle, the baffle plate is divided for woofer and mid-range tweeter. In addition, the plate thickness of the unit mounting portion is changed to 30 mm for woofer, 45 mm for mid-range, and 40 mm for tweeter. The rigidity of the baffle plate is improved. In addition, in order to reduce unnecessary radiation by reducing the baffle plate area, a slim round baffle is used.
In addition, slits are placed on the top and bottom of the woofer, and conifer material is used for the inner crosspiece to change the propagation mode, thereby minimizing vibration propagation between units. Viscoelastic material is also applied around the mid-range and tweeter to eliminate the influence of unwanted sound.

The enclosure is a cross-bridged enclosure. A single plate parallel to the baffle plate and back plate is fixed near the center of the enclosure, and another plate is crossed to fix the baffle plate and back plate. This increases the strength of the enclosure and reduces and disperses resonance.
An oak veneer is used for the exterior, and by applying a glossy coating, unnecessary resonance and sound are suppressed.

4-point grounding with coin-shaped OFC insulator. (Non-slip felt included)

It uses a large gold-plated OFC terminal that can use extra-thick cords and 4 mm plugs, and is also compatible with bi-wiring.

Model Rating

Method	3-way, 3-speaker, bass reflex system, floor type, magnetic protection design
Units Used	For low band : 27 cm cone type For Middle Area : 6 cm Dome Type For high-pass : 2.5 cm dome type
Playback frequency band	25 Hz to 45 kHz -16dB
Crossover frequency	450 Hz, 4 kHz
Impedance	6 Ω
Output sound pressure level	88dB/W/m
Allowable input	250W(MUSIC) 125W(DIN)
External dimensions	W 320x H 863x D 415 mm (w / RUNNET)
Weight	43kg