Audio Database

LUXMAN C-300
220,000yen(December, 1980 release)

Description
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The stereo control center which adopted the Duo beta plusX circuitry.

Superfluous NFB of physical characteristic priority was eliminated and the Duo beta circuitry is adopted as a technology controlled by balance with a tone quality. This circuitry makes an amplifier circuitry to the extent that it is used also from a nakedness property as it is, and adds a proper quantity of NFB and DC servoes as finish of a tone quality.
By carrying out like this, by NFB, musicality is oppressed, the transitional distorted occurrence of TIM etc. by ‚· and superfluous NFB is suppressed, and musicality is raised.

The Duo beta plusX which introduced the thought of the suitable control also into the feedback circuit of the power-source part is adopted.
The general stabilizing supply was given training in gap of an outgoing end, applied the feedback powerfully, and has lowered the impedance. On the other hand, although the impedance characteristic of the unstable power source itself rises on low-pass and a tone quality improves, there are problems low-pass dumping does not become sweet or the stability in a direct-current region is not acquired.
The low-impedance power source without the necessity of depending on a superfluous feedback was made from plusX, and the control of the control in which this nakedness property was harnessed corresponding to the amplifier circuitry in low-pass is set up in the mid-high range.

In the equalizer circuitry, the cascode bootstrap input by low-noise dual FET of high Gm was adopted as the first rank by the current mirror load intensity, and the low distortion and the high SN ratio have been obtained.
In the second step, the cascode constant current load-intensity amplifying circuit with the high fT-PNP transistor which allotted the dynamic-resistance circuitry is constituted. An electric current is sent through an output stage as a Class-A push pull stream composition with the transistor of high fT, and the margin is also given to the load intensity of the NFB element while impedance low -izing sending.

The same circuitry as an equalizer is fundamentally used for flat amplifier, and it has secured especially DC stability which carried the operational amplifier by an FET input in DC servo circuitry, and was excellent.
By this, the output capacitor was removed and coloring of sound is eliminated.

MC head amplifier of DC stream composition by a right-and-left independent source uses the first rank as the direct couple type of an FET parallel input, makes the output unit a Class-A pure complimentary push pull, arranges a voltage stabilizer for exclusive use to an adjacency, and is reducing a noise and source impedance.

The power-source part serves as right-and-left full independence from the coil of the transformer, is included to a rectifier circuit and a voltage stabilizer, and constitutes the twin monophonic power source.
This is suppressing the interference between right-and-left channels. Moreover, the tone-quality modification is aimed at by arranging the orientation of a coil the primary side of a transformer, and by the side of secondary.
A large size and mass thing is adopted as the transformer and capacitor of this power source, and low-impedance-ization is attained.

A good film capacitor is adopted as the coupling capacitor of each stage, or the capacitor of a power source, and parallel connection of the small capacity styrene capacitor is carried out to them.
All these film capacitors and most styrene capacitors arrange a polarity, and they are carrying out the tone-quality mandatory.
Moreover, the succession good transformation precision type Detent volume containing an aluminum die-casting case, the oxygen-free-high-conductivity-copper 500 core shielded cable, etc. are adopted.

Required sufficient functionality is carried, a product-line path is arranged according to the fluence of a signal, and the simplification is attained.

The turnover shift type tone control from which the balance of the purpose is obtained by simple operation is carried.
In order that a turnover frequency may carry out a succession migration according to a variation, two conventional operations are simplified.

The polarity of domestic AC plug socket is detected and the line phase sensor which can unify the polarity of an equipment is carried.

The twin T type subsonic-speed circuitry constituted only from a passive element is carried.

Furthermore, in order to improve a tone quality, various measures are taken everywhere.
Making it a chassis design by which the magnetic substance does not approach a substrate opposite side etc. has put into practice and eliminated a magnetic distortion.
Moreover, gilding is adopted as an input/output terminal, it is made the secondary fuse of a transformer with a pewter between fuse holders, and contact resistance is reduced.
Furthermore, the Tape system adopted the remote switch and has simplified the product line.

The native wood cabinet was adopted, aluminum foil was stuck on the rear view, and the shielding effect has been acquired.

Rear
Internal
Using

Rating of a mode
Form Duo beta plusX stereo control center
Output voltage Pre Out: -- standard -- a maximum of [ 1V and ] -- 20V
Rec Out: Standard 140mV, a maximum of 20v
Output load impedance Pre Out: 47ohms
Rec Out: 100ohms
THD (20Hz - 20kHz) Phono man month/MC: Less than 0.005% (Rec Out: 140mV)
Tuner, AUX: 0.005% or less (Pre Out:1V)
Monitor1, 2:0.005% or less (Rec Out:1V)
Cross modulation distortion (60Hz:7kHz=4:1) Phono man month/MC: Less than 0.002% (Rec Out: 140mV)
Tuner, AUX: 0.002% or less (Pre Out:1V)
Monitor1, 2:0.002% or less (Pre Out:1V)
Frequency characteristic Phono: 20Hz-20kHz}0.2dB
Tuner, AUX: 0.5Hz - -140kHz 0.5dB
Monitor1, -2:0.5 Hz - 140kHz 0.5dB
Input sensitivity (Pre Out:1V) Phono MC:0.09mV
Phono MM:2.0mV
Tuner, AUX: 140mV
Monitor1, 2:140mV
Input impedance Phono MC:high 100 ohm, Low 50ohm
Phono man month:man month 50kohm, MC 100ohm
Tuner, AUX:55kohm
Monitor1, 2:55kohm
SN ratio (an IHF-A correction, input short-circuit) Phono MC: -148 dB/V (input conversion noise)
Phono MM:80dB
Tuner, AUX: 100dB
Monitor1, 2:100dB
Tone control Turnover-frequency shift expression (the object for high regions, for low-pass)
Subsonic Filter 7Hz (twin T type)
Attachment MC impedance switching (high, low)
man month/MCdirect impedance switching
Tone it1 switchpoint
Rec Out switchpoint
Two tapes monitors (1, 2)
Tapes dubbing (1->2, 2->1)
Line phase sensor
Supply voltage AC100V, 50Hz/60Hz
Power consumption 25W (Electrical Appliance and Material Control Law)
AC outlet Switched: Two lines, total450W
Unswitched: One line, 500W
Dimensions Width 478x height 163x depth of 384mm
Weight 9kg