LUXMAN M-08

Commentary

A stereo power amplifier with circuit technologies such as CSSC circuits and OD β circuits.

The amplifier section uses a CSSC circuit that enables high-speed amplification.
The CSSC circuit uses a single-stage amplifier circuit of pure complimentary service directly connected to all stages. In general circuits, a multi-stage voltage amplifier circuit is used in order to increase the gain. In many cases, excessive gain must be corrected with NFB, which prevents the sound from rising and adversely affects the high-frequency characteristics. The M-08 uses a high-quality single-stage voltage amplifier to ensure the necessary and sufficient gain, and prevents the music from being atrophied by excessive gain and NFB compensation.
The first stage has a high input impedance and a complimentary service circuit of FET differentials and cascode-connected transistors with a clear operation reference point, the second stage has a grounded base circuit as a current transmission stage, and the driver stage has a 3-stage Darlington complimentary service emitter-follower circuit with high current amplification factor.
In addition, the final stage uses a multi-emitter transistor with low resistance and low loss in 3 parallel push-pull mode to obtain strong drive capability.

An OD β circuit is used to unify the sound quality over the entire band.
The OD β circuit is a circuit that goes further with the idea of the DUO β circuit with separate DC feedback originally developed by LUX. In general amplifiers, an appropriate amount of NFB is given to both AC and DC in order to unify the sound quality between the middle and low frequencies. The AC feedback mainly affects the high frequency range, and the DC feedback affects the low frequency range. However, if the DC feedback is not perfect due to the naked nature of the circuit, it is necessary to correct the low frequency range by applying a large amount of NFB using a DC servo amplifier. This DC servo amplifier has created a sense of inconsistency between the middle and low frequencies.
In the OD β circuit, 100% DC feedback is possible because the bare characteristics of the circuit are sufficiently developed. Therefore, the DC servo amplifier, which was unnecessary in terms of sound quality, is eliminated in the circuit configuration.

The power supply section employs a powerful power supply section centered on a large power transformer equivalent to 800 VA. High-grade wire is used for the wiring material and the impedance of the entire power supply path is reduced.
In addition, three windings are used for the secondary winding of the power transformer. After rectification, separate L/R regulator circuits are installed to eliminate mutual interference via the power supply. In addition, the left and right windings including the rectifier are separated for the final stage winding, and four block capacitors are installed to dramatically increase the instantaneous current supply capability.

A unique high inertia power supply is used for the power supply circuit.
A general stabilized power supply is controlled by NFB, but there is a time lag between the real time of music playback and the feedback of the real time until the control works. When observed microscopically in a short period of time, the power supply voltage constantly fluctuates greatly. Therefore, in the past, the impedance of the entire power supply was reduced as much as possible so that this fluctuation would not be visible numerically.
In the high-inertia power supply system, we focus on this area and improve the basic performance such as the capacity of the power supply unit and the instantaneous supply capability, minimize the amount of NFB, and reduce the control itself to gradually change the fluctuation. This enables natural supply with small fluctuation range even on a short time axis.

A symmetrical structure has been adopted for the housing construction. On a special FRP bottom chassis with high rigidity and large mass and 5-point grounding, rectification units such as power transformers and large block capacitors are arranged taking into consideration the front-rear balance. A large heat sink is separated to the left and right. Weight balance and internal temperature balance are maintained.
As a noise countermeasure, we have adopted a box shield structure using a shield plate to eliminate mutual interference of each circuit, and each stage is segmented to eliminate high-frequency noise and leakage flux.

Custom parts such as non-magnetic resistors, electrolytic capacitors, copper-styrene capacitors, copper bus bars, and high-purity 6-N-copper cables are used. The electrolytic capacitors in particular use high-purity aluminum foil stop ratio electrolytic capacitors with special low-temperature welded terminals. This reduces the DC resistance, which reduces the instantaneous power of sound, and makes it possible for sound to rise quickly.

In order to achieve optimum matching for control amplifiers with various output impedances and gains, it is equipped with a high-precision fixed resistance switching mute level switch for coaxial and balanced respectively.

Equipped with line phase sensor, polarity management of power supply circuit is possible.

It uses a vise type speaker terminal that can mount very thick cables.

Model Rating

Type	Stereo power amplifier
Continuous effective output	200W + 200W (8 Ω, 20 Hz to 20 kHz)
Input sensitivity	1 V (200W, 8 Ω)
Input impedance	Coaxial : 50k Ω Balance : 65k Ω
Total harmonic distortion factor	0.005% or Less (8 Ω, Both Channel Operation, Rated Output, 1 kHz)
Cross modulation distortion factor	0.008% or Less (8 Ω, Both Channel Operation, Rated Output, 1 kHz)
Frequency characteristic	20 Hz ~ 20 kHz + 0 -0.1 dB 5 Hz ~ 100 kHz + 0 -0.7 dB
Signal-to-noise ratio	120dB(IHF-A)
Attachment	Coaxial-Balance Input attenuator Line phase sensor
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	816W (Electrical Appliance and Material Control Law)
Maximum external dimensions	Width 465x Height 220x Depth 475 mm
Weight	42kg