Four independent modules in the balanced amplification circuit enable the hot and cold components of the left and right audio signals to be handled independently to suppress unnecessary noise generation. Combining an evolved version 4.0 of our traditional ODNF circuit and a robust power supply has achieved high signal-to-noise performance and improved sound quality without distortion. The 88 step range allows for more precise volume adjustment.
The C-900u has been equipped with our new LECUA* 1000, a highly precise electronically controlled attenuator which has been used in LUXMAN's 80th anniversary flagship model, the C-1000f. This system is extremely resistant to external vibration and changes in sound quality over the volume control range, as well as being extremely durable. The LECUA circuit uses stepped fixed resistance and increasing the number of steps from 72 to 88 allows more delicate volume control adjustments, with no deterioration of sound quality from 0dB to 87dB. The completely balanced configuration of the C-900u features 4 of these new LECUA 1000s in parallel, achieving ideal balanced transmission. Also, the LECUA 1000 system handles left and right balance control adjustment and level adjustment in bi-amplified output mode. The new LECUA 1000 circuit has an improved three dimensional structure and is directly connected to the amplification circuit, minimizing signal routing and improving efficiency. Our latest negative feedback circuit, ODNF** version 4.0, achieves higher performance, being quadruple paralleled in the first main amplifier stage, triple paralleled in the first error detection stage and featuring a Darlington connected second stage. Only the distorted components of an audio signal are fed back to the amplification circuit to optimize the negative feedback effect. Increased primary slew rate and ultra-wide bandwidth contribute to an extremely low level of distortion, especially in the high frequency range. An improved signal to noise ratio allows the full expression of delicate musical pieces. We have paid special attention to the shape, weightiness and texture of the volume control knob, pursuing a natural, high quality feel since this control is most frequently handled by the listener.
* LECUA stands for "LUXMAN Electrically Controlled Ultimate Attenuator"
** ODNF stands for "Only Distortion Negative Feedback"
The high performance power supply circuit features a CI type power transformer, with equivalent capacity to that of our B-1000f monaural power amplifier. Applying the philosophy of "Power Amplifier Driver", the voltage amplification stage drives the connected power amplifier stage precisely with sufficient power and is regulated by four large capacity 3,300μF blocking capacitors. The delicacy and vitality of various audio signals are transmitted to the power amplifier with the support of this remarkably stable power supply with almost no small voltage fluctuations.
The multifunctional C-900u has been equipped with user-friendliness, flexibility, and expandability to fully integrate with the listening environment. The clearly visible fluorescent display shows current input source and sound volume. A zoom function on the remote control can expand this 4 times larger. This unit is equipped with a bi-amplifier output mode, in which a balanced output circuit can be used as a 2-channel unbalanced output. An external pre-amplifier input is useful for connection to an AV system and the tone controls are electronically tuned.
The highly rigid loopless chassis used for the enclosure eliminates ground loops which can lead to deterioration in sound quality. Cast-iron isolator legs prevent resonance thanks to the characteristics of their metallic structure, the density gradient decreasing from the center to the periphery of each leg. The legs also eliminate adverse effects caused by vibration and effects from the power transformer or the supporting surface.
|Input sensitivity/Input impedance||Unbalanced 255mV/43kΩ
|Output/Input impedance||Unbalanced rating 1V/90Ω, max. 11V
Balanced rating 1V/180Ω, max. 22.5V
|Frequency response||20Hz to 20kHz (+0, -0.1dB)
5Hz to 120kHz (+0, -3.0dB)
|Total harmonic distortion||Unbalanced 0.009% (20Hz to 20kHz)
Balanced 0.005% (20Hz to 20kHz)
|S/N ratio (IHF-A)||Unbalanced 123dB
|Negative feedback circuit||ODNF 4.0|
|Max. tone control range||BASS: ±8dB at 100Hz
TREBLE: ±8dB at 10kHz
|Remote control functions||・Operation・Dimmer・ Input selector
・Output mode・Balanced phase selection
・Channel preset・External pre-amplifier input
・Line straight・Loudness・Volume up/down
2.2W (in standby mode)
|External dimensions||440(W) x 130(H) x 430(D) mm
(including 17mm front panel knob and 14 mm rear panel speaker terminals)